The effect of centre volume and procedure location on major complications and mortality from transvenous lead extraction: an ESC EHRA EORP European Lead Extraction ConTRolled ELECTRa registry subanalysis

Abstract

Aims 

Transvenous lead extraction (TLE) should ideally be undertaken by experienced operators in a setting that allows urgent surgical intervention. In this analysis of the ELECTRa registry, we sought to determine whether there was a significant difference in procedure complications and mortality depending on centre volume and extraction location.

Methods and results 

Analysis of the ESC EORP European Lead Extraction ConTRolled ELECTRa registry was conducted. Low-volume (LoV) centres were defined as <30 procedures/year, and high-volume (HiV) centres as ≥30 procedures/year. Three thousand, two hundred, and forty-nine patients underwent TLE by a primary operator cardiologist; 17.1% in LoV centres and 82.9% in HiV centres. Procedures performed by primary operator cardiologists in LoV centres were less likely to be successful (93.5% vs. 97.1%; P < 0.0001) and more likely to be complicated by procedure-related deaths (1.1% vs. 0.4%; P = 0.0417). Transvenous lead extraction undertaken by primary operator cardiologists in LoV centres were associated with increased procedure-related major complications including death (odds ratio 1.858, 95% confidence interval 1.007–3.427; P = 0.0475). Transvenous lead extraction locations varied; 52.0% operating room, 9.5% hybrid theatre and 38.5% catheterization laboratory. Rates of procedure-related major complications, including death occurring in a high-risk environment (combining operating room and hybrid theatre), were similar to those undertaken in the catheterization laboratory (1.7% vs. 1.6%; P = 0.9297).

Conclusion 

Primary operator cardiologists in LoV centres are more likely to have extractions complicated by procedure-related deaths. There was no significant difference in procedure complications between different extraction settings. These findings support the need for TLE to be performed in experienced centres with appropriate personnel present.

Centre volume, Complications, ELECTRa Registry, Mortality, Risk stratification, Transvenous lead extraction

What’s new?

• It is unclear whether patients are appropriately risk stratified prior to transvenous lead extraction to ensure complications are managed as efficiently as possible.

• Procedures are less likely to be successful if undertaken by primary operator cardiologists in low-volume (LoV) centres.

• Procedure-related deaths are more likely to result with primary operator cardiologists in LoV centres compared with high-volume centres.

• Primary operator cardiologists in LoV centres are associated with procedure-related major complications including death.

• Low-volume centres are more likely to allocate patients with high-risk characteristics to a high-risk extraction environment.

• Overall, there is no significant difference in procedure-related major complications including death when procedures are undertaken in a high-risk environment, combining the operating room and hybrid theatre, and the catheterization laboratory.

Introduction

Transvenous lead extraction (TLE) is integral in the management of infected cardiac implantable electronic devices, malfunctioning, and redundant pacemaker leads.^1–3 A multidisciplinary team approach is important and helps to determine where to undertake the extraction and which personnel are required to manage potential complications.⁴ When major complications arise a cardiothoracic surgeon and surgical team should be immediately available to ensure a thoracotomy or sternotomy is performed within 5–10 min.⁴

The ELECTRa study previously demonstrated that all-cause major complications including death were lower in high-volume (HiV) compared with low-volume (LoV) extraction centres (cut-off of 30 procedures/year) although procedure-related complications and mortality were similar.⁵ Undertaking high-risk cases in the catheterization laboratory rather than in an operating room has previously been associated with a higher risk of death.^6,7 Therefore, identifying high-risk cases pre-procedurally is very important to ensure the correct personnel are present and that the procedure is carried out in a hybrid theatre or operating room which will facilitate early intervention should a complication arise. The aim of this study was to determine whether there was any difference in procedure-related major complications and mortality between different settings and operators (LoV and HiV centres and cardiologists and cardiothoracic surgeons).

Methods

The design and results of the ELECTRa study has been previously published.⁵ The executive committee in collaboration with the EURObservational Research Programme (EORP) provided the study design, protocol, and scientific leadership of the registry under the responsibility of the European Heart Rhythm Association Scientific Initiative Committee. Overall, 3555 consecutive patients were enrolled, of which 3510 patients underwent TLE in 73 centres across 19 European centres between 2012 and 2014.⁵ High-volume centres were defined as ≥30 TLE procedures/year and LoV centres as <30 TLE procedures/year. Accordingly, 2915 (82.0%) patients underwent TLE in HiV centres and 628 (18.0%) underwent TLE in LoV centres. In the current analysis, we investigated the difference in procedure-related major complications including death depending on the primary operator and location for TLE. We used procedure-related major complications including death as the main outcome measure, since this is most likely to influence the location for TLE and determine which personnel are required. A high-risk environment for TLE was considered to consist of both the operating room and hybrid theatre since this environment can facilitate urgent surgical intervention to manage complications. Their outcomes were combined and compared with those of the catheterization laboratory.

Statistical analysis

The results are presented as mean ± standard deviation for normally distributed variables and as median (interquartile range) for non-normally distributed variables. A χ² was used for among-group comparisons or a Fisher’s exact test if the expected cell count was less than five. Univariable and multivariable binary logistic regression was performed to determine predictors of procedure-related major complications including death and procedure-related death. Variables statistically significant at univariable analysis and important clinical covariables were used as the basis for multivariable analysis. A two-sided P-value of <0.05 was considered statistically significant. Statistical analyses were performed using Prism (GraphPad Software Inc., Version 8, CA, USA) and SPSS (IBM Switzerland, Version 25, Switzerland).

Results

Cardiologists as the primary operator in high- and low-volume centres

Overall, 3249/3510 (92.6%) patients underwent TLE with a cardiologist as the primary operator; 2694 (82.9%) patients in HiV centres and 555 (17.1%) patients in LoV centres. Baseline demographics, indications, extraction tools, and outcomes in HiV and LoV centres with cardiologists as the primary operator are given in Table 1. Patients undergoing TLE by cardiologists as the primary operator in LoV and HiV centres were matched in terms of age (65.5 ± 16.7 vs. 64.8 ± 15.4 years; P = 0.0661), female gender (25.1% vs. 28.0%; P = 0.1573) and infectious indication for TLE (56.5% vs. 52.4%; P = 0.0744). Primary operator cardiologists in LoV centres were more likely to undertake TLE on patients with more advanced New York Heart Association functional Class III–IV (39.5% vs. 30.3%; P = 0.0052), lower body mass index [25.7 (23.3–28.7) vs. 26.2 (23.8–29.4) kg/m²; P = 0.0074] and dilated cardiomyopathy (31.1% vs. 25.9%; P = 0.0120).

Table 1

A comparison of procedural-related major complications including death between cardiologists as the primary operator in high- and low-volume centres

Variables	Total (N = 3249)	High-volume cardiologist (N = 2694)	Low-volume cardiologist (N = 555)	P-value
Characteristics, n/N (%)
Age (years)	64.95 ± 15.61	64.83 ± 15.38	65.54 ± 16.65	0.0661
Female, n/N (%)	893/3249 (27.49)	754/2694 (27.99)	139/555 (25.05)	0.1573
Body mass index (kg/m2), median (IQR)	26.10 (23.70–29.30)	26.20 (23.80–29.40)	25.70 (23.30–28.70)	0.0074
Left ventricular ejection fraction (%), median (IQR)	48.00 (32.00–60.00)	48.00 (32.00–60.00)	50.00 (33.00–60.00)	0.2182
New York Heart Association Class III–IV	454/1428 (31.79)	360/1190 (30.25)	94/238 (39.50)	0.0052
Comorbidities, n/N (%)
Coronary artery disease	1292/3222 (40.10)	1069/2671 (40.02)	223/551 (40.47)	0.8446
Hypertension	1753/3218 (54.47)	1459/2664 (54.77)	294/554 (53.07)	0.4651
Diabetes mellitus	727/3226 (22.54)	604/2672 (22.60)	123/554 (22.20)	0.8365
Chronic heart failure	1466/3228 (45.42)	1222/2679 (45.61)	244/549 (44.44)	0.6161
Dilated cardiomyopathy	865/3234 (26.75)	693/2680 (25.86)	172/554 (31.05)	0.0120
Chronic kidney disease	574/3233 (17.75)	462/2678 (17.25)	112/555 (20.18)	0.1003
Chronic obstructive pulmonary disease	275/3223 (8.53)	221/2678 (8.25)	54/545 (9.91)	0.2072
Indication, n/N (%)
Infection	1720/3241 (53.07)	1408/2689 (52.36)	312/552 (56.52)	0.0744
Local infection	1093/3241 (33.72)	905/2689 (33.66)	188/552 (34.06)	0.8555
Systemic infection	612/3241 (18.88)	496/2689 (18.45)	116/552 (21.01)	0.1601
No infection	1529/3249 (47.06)	1286/2694 (47.74)	243/555 (43.78)	0.0894
Dwell time (years), median (IQR)	5.33 (3.00–8.00)	6.00 (3.00–8.00)	5.00 (2.00–8.00)	0.0319
Sheaths, n/N (%)
Powered sheaths (any)	921/3247 (28.36)	761/2692 (28.27)	160/555 (28.83)	0.7899
Laser sheaths	636/3247 (19.59)	551/2692 (20.47)	85/555 (15.32)	0.0054
Evolution® mechanical dilator sheaths	282/3247 (8.68)	208/2692 (7.73)	74/555 (13.33)	<0.0001
Electrosurgical dissection sheaths	5/3247 (0.15)	4/2692 (0.15)	1/555 (0.18)	1.0000
Femoral approach for at least one lead	143/3249 (4.40)	109/2694 (4.05)	34/555 (6.13)	0.0296
Clinical success n/N (%)	3136/3249 (96.52)	2617/2694 (97.14)	519/555 (93.51)	<0.0001
Complications, n/N (%)
Procedural-related major complications including death	56/3249 (1.72)	41/2694 (1.52)	15/555 (2.70)	0.0516
Intra-procedural	35/3249 (1.08)	25/2694 (0.93)	10/555 (1.80)	0.0694
Post-procedural	21/3249 (0.65)	16/2694 (0.59)	5/555 (0.90)	0.3859
Procedural-related deaths	16/3249 (0.49)	10/2694 (0.37)	6/555 (1.08)	0.0417
Intra-procedural	8/3249 (0.25)	4/2694 (0.15)	4/555 (0.72)	0.0331
Post-procedural	8/3249 (0.25)	6/2694 (0.22)	2/555 (0.36)	0.6314
Cardiac avulsion or tear	28/3249 (0.86)	22/2694 (0.82)	6/555 (1.08)	0.6117
Vascular avulsion or tear	19/3249 (0.58)	12/2694 (0.45)	7/555 (1.26)	0.0313

IQR, interquartile range.

Primary operator cardiologists in HiV centres were more likely to extract leads with a longer dwell time [6 (3–8) vs. 5 (2–8) years; P = 0.0319] and were less likely to use a femoral approach to carry out the procedure (4.1% vs. 6.1%; P = 0.0296). Although the use of powered sheaths was similar between primary operator cardiologists in HiV and LoV centres (28.3% vs. 28.8%; P = 0.7899), primary operator cardiologists in HiV centres were more likely to use laser sheaths (20.5% vs. 15.3%; P = 0.0054) and less likely to use Evolution^® mechanical dilator sheaths (7.7% vs. 13.3%; P < 0.0001). Primary operator cardiologists in HiV centres were significantly more likely to have a successful procedure (97.1% vs. 93.5%; P < 0.0001).

Overall procedure-related major complications including death (1.5% vs. 2.7%; P = 0.0516), including intra-procedure major complications including death (0.9% vs. 1.8%; P = 0.0694) were not statistically different between primary operator cardiologists in HiV and LoV centres. There was, however, a statistically significantly higher proportion of procedure-related deaths when TLE’s were performed by a cardiologist as the primary operator in LoV vs. HiV centres (1.1% vs. 0.4%; P = 0.0417); including intra-procedural deaths (0.7% vs. 0.2%; P = 0.0331) with a statistically higher number of vascular avulsion or tear (1.3 vs. 0.5%; P = 0.0313). With multivariable binary logistic regression, primary operator cardiologists performing TLE in LoV centres were associated with procedure-related major complications including death [odds ratio (OR) 1.858, 95% confidence interval (CI) 1.007–3.427; P = 0.0475], procedure-related deaths (OR 2.877, 95% CI 1.034–8.005; P = 0.0430) (Figure 1), intra-procedure deaths (OR 4.887, 95% CI 1.218–19.606; P = 0.0252), and vascular avulsion or tear (OR 3.016, 95% CI 1.174–7.750; P = 0.0219).

Figure 1

Predictors of procedure-related major complications including death and procedural-related deaths. CI, confidence interval. ^aAdjusted for all variables shown.

Cardiothoracic surgeons as the primary operator

In total, 258/3510 (7.4%) patients underwent TLE with a cardiothoracic surgeon as the primary operator. There were 56 (1.7%) procedure-related major complications including death when a cardiologist was the primary operator and 2 (0.8%) when a cardiothoracic surgeon was the primary operator (P = 0.4401). There was no significant difference in procedure-related deaths with 16 (0.5%) deaths occurring with a primary operator cardiologist and 1 (0.4%) death occurring with a primary operator cardiothoracic surgeon (P = 1.0000). There were 186 (72.1%) procedures undertaken by primary operator cardiothoracic surgeons in HiV centres and 72 (27.9%) procedures in LoV centres. There was no significant difference in procedure-related major complications including death (1.1% vs. 0.0%; P = 1.0000) and procedure-related deaths (0.5% vs. 0.0%; P = 1.0000).

Comparison of outcomes when both a cardiologist and cardiothoracic surgeon were present

Transvenous lead extraction was carried out in 2952 (84.2%) patients with only a cardiologist present and in 556 (15.8%) patients with both a cardiologist and cardiothoracic surgeon present. These procedures were carried out in the operating room in 295 (53.0%) patients, hybrid theatre in 110 (19.8%) patients, and catheterization laboratory in 151 (27.2%) patients. Baseline patient demographics, indications, tools for TLE and outcomes for procedures undertaken by cardiologists alone and when cardiologists and cardiothoracic surgeons were present are given in Table 2.

Table 2

A comparison of procedural-related major complications including death according to whether a surgeon was present during the case in all centres

Variables	Total (N = 3508)	Cardiologist and no surgeon present (N = 2952)	Cardiologist and surgeon present (N = 556)	P-value
Characteristics, n/N (%)
Age (years)	64.88 ± 15.62	65.13 ± 15.28	63.58 ± 17.31	0.2595
Female, n/N (%)	971/3508 (27.68)	805/2952 (27.27)	166/556 (29.86)	0.2111
Body mass index (kg/m2), median (IQR)	26.10 (23.50–29.30)	26.10 (23.50–29.30)	26.10 (23.63–28.70)	0.3678
Left ventricular ejection fraction (%), median (IQR)	50.00 (33.00–60.00)	48.00 (33.00–60.00)	50.00 (35.00–60.00)	<0.0001
New York Heart Association Class III–IV	486/1517 (32.04)	410/1286 (31.88)	76/231 (32.90)	0.7600
Comorbidities, n/N (%)
Coronary artery disease	1373/3480 (39.45)	1168/2931 (39.85)	205/549 (37.34)	0.2696
Hypertension	1887/3476 (54.29)	1571/2923 (53.75)	316/553 (57.14)	0.1415
Diabetes mellitus	780/3485 (22.38)	672/2930 (22.94)	108/555 (19.46)	0.0717
Chronic heart failure	1555/3486 (44.61)	1319/2931 (45.00)	236/555 (42.52)	0.2813
Dilated cardiomyopathy	916/3490 (26.25)	789/2936 (26.87)	127/554 (22.92)	0.0527
Chronic kidney disease	612/3491 (17.53)	514/2935 (17.51)	98/556 (17.63)	0.9487
Chronic obstructive pulmonary disease	297/3481 (8.53)	247/2930 (8.43)	50/551 (9.07)	0.6194
Indication, n/N (%)
Infection	1863/3497 (53.27)	1564/2945 (53.11)	299/552 (54.17)	0.6470
Local infection	1169/3497 (33.43)	982/2945 (33.34)	187/552 (33.88)	0.8078
Systemic infection	679/3497 (19.42)	568/2945 (19.29)	111/552 (20.11)	0.6542
No infection	1645/3508 (46.89)	1388/2952 (47.02)	257/556 (46.22)	0.7301
Dwell time (years), median (IQR)	5.33 (3.00–8.00)	5.00 (2.17–8.00)	6.00 (3.13–9.00)	0.0003
Sheaths, n/N (%)
Powered sheaths (any)	1090/3506 (31.09)	826/2950 (28.00)	264/556 (47.48)	<0.0001
Laser sheaths	758/3506 (21.62)	526/2950 (17.83)	232/556 (41.73)	<0.0001
Evolution® mechanical dilator sheaths	332/3506 (9.47)	301/2950 (10.20)	31/556 (5.58)	0.0006
Electrosurgical dissection sheaths	5/3506 (0.14)	4/2950 (0.14)	1/556 (0.18)	0.5785
Femoral approach for at least one lead	150/3508 (4.28)	121/2952 (4.10)	29/556 (5.22)	0.2324
Clinical success n/N (%)	3393/3508 (96.72)	2872/2952 (97.29)	521/556 (93.71)	<0.0001
Complications, n/N (%)
Procedural-related major complications including death	58/3508 (1.65)	34/2952 (1.15)	24/556 (4.32)	<0.0001
Intra-procedural	37/3508 (1.05)	24/2952 (0.81)	13/556 (2.34)	0.0012
Post-procedural	21/3508 (0.60)	10/2952 (0.34)	11/556 (1.98)	0.0001
Procedural-related deaths	17/3508 (0.48)	11/2952 (0.37)	6/556 (1.08)	0.0402
Intra-procedural	9/3508 (0.26)	5/2952 (0.17)	4/556 (0.72)	0.0405
Post-procedural	8/3508 (0.23)	6/2952 (0.20)	2/556 (0.36)	0.3697
Cardiac avulsion or tear	30/3508 (0.86)	21/2952 (0.71)	9/556 (1.62)	0.0430
Vascular avulsion or tear	20/3508 (0.57)	9/2952 (0.30)	11/556 (1.98)	0.0001

IQR, interquartile range.

The groups were matched in terms of age (65.1 ± 15.3 vs. 63.6 ± 17.3 years; P = 0.2595), female gender (27.3% vs. 29.9%; P = 0.2111), body mass index [26.1 (23.5–29.3) vs. 26.1 (23.6–28.7) kg/m²; P = 0.3678], chronic heart failure (45.0% vs. 42.5%; P = 0.2813), and infectious indication for TLE (53.1% vs. 54.2%; P = 0.6470). Patients undergoing procedures by solely cardiologists were more likely to have a severely impaired left ventricular systolic function [48 (33–60)% vs. 50 (35–60)%; P < 0.0001]. Lead dwell time was significantly longer when cardiologists and cardiothoracic surgeons were present [6 (3–9) vs. 5 (2–8) years; P = 0.0003]. Transvenous lead extraction’s carried out when both a cardiologist and cardiothoracic were present were more likely to involve powered sheaths (47.5% vs. 28.0%; P < 0.0001) including laser sheaths (41.7% vs. 17.8%; P < 0.0001) and procedures were less likely to be successful (93.7% vs. 97.3%; P < 0.0001). There were 24 (4.3%) procedure-related major complications including death when both a cardiologist and cardiothoracic surgeon were present compared with only 34 (1.2%) events when solely a cardiologist was present (P < 0.0001). Furthermore, the presence of both a cardiologist and cardiothoracic surgeon during the procedure resulted in significantly higher proportion of cardiac avulsion or tear (1.6% vs. 0.7%; P = 0.0430), vascular avulsion or tear (2.0% vs. 0.3%; P = 0.0001) and procedure-related deaths (1.1% vs. 0.4%; P = 0.0402) including intra-procedure-related deaths (0.7% vs. 0.2%; P = 0.0405). At multivariable binary logistic regression, the presence of a cardiologist and cardiothoracic surgeon was predictive of procedure-related major complications including death (OR 3.094, 95% CI 1.789–5.352; P = 0.0001) (Figure 2), including vascular avulsion or tear (OR 4.666, 95% CI 1.896–11.481; P = 0.0008) but not procedure-related deaths (OR 2.592, 95% CI 0.937–7.174; P = 0.0667), nor cardiac avulsion or tear (OR 1.989, 95% CI 0.892–4.434; P = 0.0928).

Figure 2

Predictors of procedure-related major complications including death. CI, confidence interval. ^aAdjusted for all variables shown.

There was no significant difference in procedural-related major complications including death when a cardiologist and cardiothoracic surgeon were both present during the procedure in HiV vs. LoV centres (4.13% vs. 5.00%; P = 0.6774).

Extraction location

Overall complications in different extraction locations

Transvenous lead extraction was carried out in 1824 (52.0%) patients in the operating room, 335 (9.5%) patients in the hybrid theatre, and 1351 (38.5%) patients in the catheterization laboratory. Baseline patient demographics and complications according to different extraction locations are provided in Table 3, with a higher risk area consisting of both the operating room and hybrid theatre, compared with the catheterization laboratory. A significantly higher proportion of patients undergoing TLE in the catheterization laboratory were older (66.8 ± 14.6 vs. 63.7 ± 16.1 years; P < 0.0001), had worse left ventricular systolic function [45 (31–60)% vs. 50 (35–60)%; P = 0.0439], New York Heart Association Class III–IV (35.3% vs. 29.7%; P = 0.0209), chronic heart failure (46.8% vs. 43.3%; P = 0.0453), chronic kidney disease (20.4% vs. 15.8%; P = 0.0005), infectious indication for TLE (63.6% vs. 46.9%; P < 0.0001), and a shorter lead dwell time [5 (2–8) vs. 6 (3–9) years; P < 0.0001]. Furthermore, procedures in the catheterization laboratory were more likely to involve the use of powered sheaths (34.8% vs. 28.8%; P = 0.0002) which was predominantly due to the use of laser sheaths (26.1% vs. 18.9%; P < 0.0001). There 22 (1.6%) procedure-related major complications including death occurring in the catheterization laboratory and 36 (1.7%) complications in high-risk areas (P = 0.9297). There was no significant difference in terms of procedure-related deaths (0.4% vs. 0.6%; P = 0.4406), cardiac avulsion or tear (0.6% vs. 1.0%; P = 0.1813), and vascular avulsion or tear (0.7% vs. 0.5%; P = 0.5485). At multivariable binary logistic regression, a high-risk environment was not associated with procedure-related major complications including death (OR 0.884, 95% CI 0.299–2.615; P = 0.8234).

Table 3

A comparison of procedural-related major complications including death when carried out in different locations

Variables	Total (N = 3510)	Operating room (N = 1824)	Hybrid theatre (N = 335)	Operating room and hybrid theatre (N = 2159)	Catheterization laboratory (N = 1351)	P-value
Characteristics, n/N (%)
Age (years)	64.88 ± 15.62	64.37 ± 15.45	60.07 ± 18.92	63.70 ± 16.11	66.77 ± 14.61	<0.0001
Female, n/N (%)	971/3510 (27.66)	546/1824 (29.93)	110/335 (32.84)	656/2159 (30.38)	315/1351 (23.32)	<0.0001
Body mass index (kg/m2), median (IQR)	26.10 (23.50–29.30)	26.10 (23.50–29.28)	26.35 (23.63–29.38)	26.10 (23.50–29.30)	26.10 (23.70–29.23)	0.9980
Left ventricular ejection fraction (%), median (IQR)	50.00 (33.00–60.00)	50.00 (35.00–60.00)	50.00 (34.50–60.00)	50.00 (35.00–60.00)	45.00 (31.00–60.00)	0.0439
New York Heart Association Class III–IV	486/1519 (31.99)	215/744 (28.90)	52/155 (33.55)	267/899 (29.70)	219/620 (35.32)	0.0209
Comorbidities, n/N (%)
Coronary artery disease	1375/3482 (39.49)	723/1812 (39.90)	116/333 (34.83)	839/2145 (39.11)	536/1337 (40.09)	0.5668
Hypertension	1888/3478 (54.28)	938/1807 (51.91)	165/334 (49.40)	1103/2141 (51.52)	785/1337 (58.71)	<0.0001
Diabetes mellitus	781/3487 (22.40)	384/1819 (21.11)	51/334 (15.27)	435/2153 (20.20)	346/1334 (25.94)	0.0001
Chronic heart failure	1557/3488 (44.64)	772/1811 (42.63)	156/332 (46.99)	928/2143 (43.30)	629/1345 (46.77)	0.0453
Dilated cardiomyopathy	917/3492 (26.26)	415/1815 (22.87)	61/334 (18.26)	476/2149 (22.15)	441/1343 (32.84)	<0.0001
Chronic kidney disease	613/3493 (17.55)	279/1820 (15.33)	61/334 (18.26)	340/2154 (15.78)	273/1339 (20.39)	0.0005
Chronic obstructive pulmonary disease	297/3483 (8.53)	130/1806 (7.20)	20/335 (5.97)	150/2141 (7.01)	147/1342 (10.95)	<0.0001
Indication, n/N (%)
Infection	1865/3499 (53.30)	855/1819 (47.00)	154/334 (46.11)	1009/2153 (46.86)	856/1346 (63.60)	<0.0001
Local infection	1170/3499 (33.44)	502/1819 (27.60)	94/334 (28.14)	596/2153 (27.68)	574/1346 (42.64)	<0.0001
Systemic infection	680/3499 (19.43)	347/1819 (19.08)	56/334 (16.77)	403/2153 (18.72)	277/1346 (20.58)	0.1758
No infection	1645/3510 (46.87)	969/1824 (53.13)	181/335 (54.03)	1150/2159 (53.27)	495/1351 (36.64)	<0.0001
Dwell time (years), median (IQR)	5.33 (3.00–8.00)	6.00 (3.00–8.59)	6.00 (4.00–9.50)	6.00 (3.00–9.00)	5.00 (2.00–8.00)	<0.0001
Sheaths, n/N (%)
Powered sheaths (any)	1091/3508 (31.10)	516/1823 (28.30)	105/335 (31.34)	621/2158 (28.78)	470/1350 (34.81)	0.0002
Laser sheaths	759/3508 (21.64)	352/1823 (19.31)	55/335 (16.42)	407/2158 (18.86)	352/1350 (26.07)	<0.0001
Evolution® mechanical dilator sheaths	332/3508 (9.46)	167/1823 (9.16)	49/335 (14.63)	216/2158 (10.01)	116/1350 (8.59)	0.1631
Electrosurgical dissection sheaths	5/3508 (0.14)	0/1823 (0.00)	1/335 (0.30)	1/2158 (0.05)	4/1350 (0.30)	0.0758
Femoral approach for at least one lead	150/3510 (4.27)	69/1824 (3.78)	18/335 (5.37)	87/2159 (4.03)	63/1351 (4.66)	0.3665
Clinical success n/N (%)	3395/3510 (96.72)	1772/1824 (97.15)	322/335 (96.12)	2094/2159 (96.99)	1301/1351 (96.30)	0.2636
Complications, n/N (%)
Procedural-related major complications including death	58/3510 (1.65)	31/1824 (1.70)	5/335 (1.49)	36/2159 (1.67)	22/1351 (1.63)	0.9297
Intra-procedural	37/3510 (1.05)	22/1824 (1.21)	4/335 (1.19)	26/2159 (1.20)	11/1351 (0.81)	0.2709
Post-procedural	21/3510 (0.60)	9/1824 (0.49)	1/335 (0.30)	10/2159 (0.46)	11/1351 (0.81)	0.1895
Procedural-related deaths	17/3510 (0.48)	11/1824 (0.60)	1/335 (0.30)	12/2159 (0.56)	5/1351 (0.37)	0.4406
Intra-procedural	9/3510 (0.26)	6/1824 (0.33)	1/335 (0.30)	7/2159 (0.32)	2/1351 (0.15)	0.4965
Post-procedural	8/3510 (0.23)	5/1824 (0.27)	0/335 (0.00)	5/2159 (0.23)	3/1351 (0.22)	1.0000
Cardiac avulsion or tear	30/3510 (0.85)	19/1824 (1.04)	3/335 (0.90)	22/2159 (1.02)	8/1351 (0.59)	0.1813
Vascular avulsion or tear	20/3510 (0.57)	9/1824 (0.49)	2/335 (0.60)	11/2159 (0.51)	9/1351 (0.67)	0.5485

IQR, interquartile range.

Complications according to location in high- and low-volume centres

In HiV centres, the majority of TLE procedures were carried out in the operating room in 1651 (57.3%) patients, in the hybrid theatre in 231 (8.0%) patients and in the catheterization laboratory in 1000 (34.7%) patients. Baseline patient demographics and complications according to different HiV extraction locations are provided in Table 4, including a comparison of catheterization laboratory and high-risk areas. Patients undergoing TLE in the catheterization laboratory in HiV centres were more likely to be older (P < 0.0001), New York Heart Association Class III–IV (P = 0.0205), chronic heart failure (P = 0.0327), chronic kidney disease (P = 0.0001), infectious indication for TLE (P < 0.0001), shorter lead dwell time (P < 0.0001), and use powered sheaths (P < 0.0001).

Table 4

A comparison of procedural-related major complications including death when carried out in different high-volume locations

Variables	Total (N = 2882)	Operating room (N = 1651)	Hybrid theatre (N = 231)	Operating room and hybrid theatre (N = 1882)	Catheterization laboratory (N = 1000)	P-value
Characteristics, n/N (%)
Age (years)	64.83 ± 15.39	64.24 ± 15.33	59.79 ± 17.88	63.70 ± 15.73	66.98 ± 14.51	<0.0001
Female, n/N (%)	812/2882 (28.17)	504/1651 (30.53)	82/231 (35.50)	586/1882 (31.14)	226/1000 (22.60)	<0.0001
Body mass index (kg/m2), median (IQR)	26.20 (23.70–29.30)	26.20 (23.60–29.40)	26.80 (24.05–29.70)	26.30 (23.70–29.40)	26.10 (23.70–29.10)	0.3823
Left ventricular ejection fraction (%), median (IQR)	48.00 (33.00–60.00)	49.00 (34.00–60.00)	50.00 (35.00–60.00)	50.00 (34.00–60.00)	45.00 (30.00–60.00)	0.0551
New York Heart Association Class III–IV	386/1254 (30.78)	193/680 (28.38)	30/104 (28.85)	223/784 (28.44)	163/470 (34.68)	0.0205
Comorbidities, n/N (%)
Coronary artery disease	1131/2858 (39.57)	664/1639 (40.51)	77/230 (33.48)	741/1869 (39.65)	390/989 (39.43)	0.9118
Hypertension	1548/2851 (54.30)	846/1634 (51.77)	104/231 (45.02)	950/1865 (50.94)	598/986 (60.65)	<0.0001
Diabetes mellitus	639/2860 (22.34)	345/1646 (20.96)	32/231 (13.85)	377/1877 (20.09)	262/983 (26.65)	0.0001
Chronic heart failure	1286/2866 (44.87)	708/1639 (43.20)	104/231 (45.02)	812/1870 (43.42)	474/996 (47.59)	0.0327
Dilated cardiomyopathy	740/2866 (25.82)	383/1643 (23.31)	36/230 (15.65)	419/1873 (22.37)	321/993 (32.33)	<0.0001
Chronic kidney disease	494/2866 (17.24)	245/1648 (14.87)	40/230 (17.39)	285/1878 (15.18)	209/988 (21.15)	0.0001
Chronic obstructive pulmonary disease	235/2866 (8.20)	115/1642 (7.00)	7/231 (3.03)	122/1873 (6.51)	113/993 (11.38)	<0.0001
Indication, n/N (%)
Infection	1516/2876 (52.71)	753/1648 (45.69)	90/231 (38.96)	843/1879 (44.86)	673/997 (67.50)	<0.0001
Local infection	964/2876 (33.52)	448/1648 (27.18)	59/231 (25.54)	507/1879 (26.98)	457/997 (45.84)	<0.0001
Systemic infection	545/2876 (18.95)	300/1648 (18.20)	31/231 (13.42)	331/1879 (17.62)	214/997 (21.46)	0.0122
No infection	1366/2882 (47.40)	898/1651 (54.39)	141/231 (61.04)	1039/1882 (55.21)	327/1000 (32.70)	<0.0001
Dwell time (years), median (IQR)	5.67 (3.00–8.25)	6.00 (3.00–8.50)	6.00 (4.00–10.00)	6.00 (3.00–9.00)	5.00 (2.00–8.00)	<0.0001
Sheaths, n/N (%)
Powered sheaths (any)	905/2880 (31.42)	444/1650 (26.91)	68/231 (29.44)	512/1881 (27.22)	393/999 (39.34)	<0.0001
Laser sheaths	656/2880 (22.78)	292/1650 (17.70)	40/231 (17.32)	332/1881 (17.65)	324/999 (32.43)	<0.0001
Evolution® mechanical dilator sheaths	250/2880 (8.68)	155/1650 (9.39)	28/231 (12.12)	183/1881 (9.73)	67/999 (6.71)	0.0061
Electrosurgical dissection sheaths	4/2880 (0.14)	0/1650 (0.00)	0/231 (0.00)	0/1881 (0.00)	4/999 (0.40)	0.0144
Femoral approach for at least one lead	112/2882 (3.89)	62/1651 (3.76)	8/231 (3.46)	70/1882 (3.72)	42/1000 (4.20)	0.5252
Clinical success n/N (%)	2803/2882 (97.26)	1609/1651 (97.46)	223/231 (96.54)	1832/1882 (97.34)	971/1000 (97.10)	0.7034
Complications, n/N (%)
Procedural-related major complications including death	43/2882 (1.49)	25/1651 (1.51)	3/231 (1.30)	28/1882 (1.49)	15/1000 (1.50)	0.9794
Intra-procedural	27/2882 (0.94)	16/1651 (0.97)	2/231 (0.87)	18/1882 (0.96)	9/1000 (0.90)	0.8810
Post-procedural	16/2882 (0.56)	9/1651 (0.55)	1/231 (0.43)	10/1882 (0.53)	6/1000 (0.60)	0.8134
Procedural-related deaths	11/2882 (0.38)	8/1651 (0.48)	1/231 (0.43)	9/1882 (0.48)	2/1000 (0.20)	0.3487
Intra-procedural	5/2882 (0.17)	3/1651 (0.18)	1/231 (0.43)	4/1882 (0.21)	1/1000 (0.10)	0.6644
Post-procedural	6/2882 (0.21)	5/1651 (0.30)	0/231 (0.00)	5/1882 (0.27)	1/1000 (0.10)	0.6713
Cardiac avulsion or tear	24/2882 (0.83)	15/1651 (0.91)	2/231 (0.87)	17/1882 (0.90)	7/1000 (0.70)	0.5675
Vascular avulsion or tear	13/2882 (0.45)	7/1651 (0.42)	1/231 (0.43)	8/1882 (0.43)	5/1000 (0.50)	0.7758

IQR, interquartile range.

There was no significant difference between the catheterization laboratory and high-risk environment in terms of procedure-related major complications including death (1.5% vs. 1.5%; P = 0.9794), procedure-related deaths (0.2% vs. 0.5%; P = 0.3487), cardiac avulsion or tear (0.7% vs. 0.9%; P = 0.5675), and vascular avulsion or tear (0.5% vs. 0.4%; P = 0.7758).

In LoV centres, TLE procedures were most commonly performed in the catherization laboratory in 351 (55.9%) patients, in 173 (27.5%) patients in the operating room and 104 (16.6%) patients in the hybrid theatre. Baseline patient demographics and complications according to different LoV extraction locations are provided in Table 5, including a comparison of catheterization laboratory and high-risk areas. Patients undergoing TLE in high-risk areas were more likely to have a lower body mass index (P = 0.0093), infectious indication for TLE (P = 0.0420), longer lead dwell time (P = 0.0200), and use powered sheaths (P < 0.0001), particularly laser sheaths (P < 0.0001).

Table 5

A comparison of procedural-related major complications including death when carried out in different low-volume locations

Variables	Total (N = 628)	Operating room (N = 173)	Hybrid theatre (N = 104)	Operating room and hybrid theatre (N = 277)	Catheterization laboratory (N = 351)	P-value
Characteristics, n/N (%)
Age (years)	65.11 ± 16.63	65.60 ± 16.56	60.67 ± 21.12	63.75 ± 18.52	66.17 ± 14.92	0.3146
Female, n/N (%)	159/628 (25.32)	42/173 (24.28)	28/104 (26.92)	70/277 (25.27)	89/351 (25.36)	0.9805
Body mass index (kg/m2), median (IQR)	25.70 (23.30–28.70)	25.20 (22.90–28.20)	25.10 (22.75–28.65)	25.15 (22.90–28.60)	26.10 (23.50–29.30)	0.0093
Left ventricular ejection fraction (%), median (IQR)	50.00 (35.00–60.00)	53.50 (40.00–60.00)	50.00 (30.00–60.00)	50.00 (35.00–60.00)	50.00 (33.00–60.00)	0.1256
New York Heart Association Class III–IV	100/265 (37.74)	22/64 (34.38)	22/51 (43.14)	44/115 (38.26)	56/150 (37.33)	0.8773
Comorbidities, n/N (%)
Coronary artery disease	244/624 (39.10)	59/173 (34.10)	39/103 (37.86)	98/276 (35.51)	146/348 (41.95)	0.1012
Hypertension	340/627 (54.23)	92/173 (53.18)	61/103 (59.22)	153/276 (55.43)	187/351 (53.28)	0.5902
Diabetes mellitus	142/627 (22.65)	39/173 (22.54)	19/103 (18.45)	58/276 (21.01)	84/351 (23.93)	0.3863
Chronic heart failure	271/622 (43.57)	64/172 (37.21)	52/101 (51.49)	116/273 (42.49)	155/349 (44.41)	0.6315
Dilated cardiomyopathy	177/626 (28.27)	32/172 (18.60)	25/104 (24.04)	57/276 (20.65)	120/350 (34.29)	0.0002
Chronic kidney disease	119/627 (18.98)	34/172 (19.77)	21/104 (20.19)	55/276 (19.93)	64/351 (18.23)	0.5913
Chronic obstructive pulmonary disease	62/617 (10.05)	15/164 (9.15)	13/104 (12.50)	28/268 (10.45)	34/349 (9.74)	0.7726
Indication, n/N (%)
Infection	349/623 (56.02)	102/171 (59.65)	64/103 (62.14)	166/274 (60.58)	183/349 (52.44)	0.0420
Local infection	206/623 (33.07)	54/171 (31.58)	35/103 (33.98)	89/274 (32.48)	117/349 (33.52)	0.7836
Systemic infection	135/623 (21.67)	47/171 (27.49)	25/103 (24.27)	72/274 (26.28)	63/349 (18.05)	0.0134
No infection	279/628 (44.43)	71/173 (41.04)	40/104 (38.46)	111/277 (40.07)	168/351 (47.86)	0.0511
Dwell time (years), median (IQR)	5.00 (2.00–8.00)	5.67 (3.00–9.00)	6.00 (2.50–9.00)	6.00 (3.00–9.00)	5.00 (2.00–8.00)	0.0200
Sheaths, n/N (%)
Powered sheaths (any)	186/628 (29.62)	72/173 (41.62)	37/104 (35.58)	109/277 (39.35)	77/351 (21.94)	<0.0001
Laser sheaths	103/628 (16.40)	60/173 (34.68)	15/104 (14.42)	75/277 (27.08)	28/351 (7.98)	<0.0001
Evolution® mechanical dilator sheaths	82/628 (13.06)	12/173 (6.94)	21/104 (20.19)	33/277 (11.91)	49/351 (13.96)	0.4497
Electrosurgical dissection sheaths	1/628 (0.16)	0/173 (0.00)	1/104 (0.96)	1/277 (0.36)	0/351 (0.00)	0.4411
Femoral approach for at least one lead	38/628 (6.05)	7/173 (4.05)	10/104 (9.62)	17/277 (6.14)	21/351 (5.98)	0.9358
Clinical success n/N (%)	592/628 (94.27)	163/173 (94.22)	99/104 (95.19)	262/277 (94.58)	330/351 (94.02)	0.7612
Complications, n/N (%)
Procedural-related major complications including death	15/628 (2.39)	6/173 (3.47)	2/104 (1.92)	8/277 (2.89)	7/351 (1.99)	0.4664
Intra-procedural	10/628 (1.59)	6/173 (3.47)	2/104 (1.92)	8/277 (2.89)	2/351 (0.57)	0.0259
Post-procedural	5/628 (0.80)	0/173 (0.00)	0/104 (0.00)	0/277 (0.00)	5/351 (1.42)	0.0702
Procedural-related deaths	6/628 (0.96)	3/173 (1.73)	0/104 (0.00)	3/277 (1.08)	3/351 (0.85)	1.0000
Intra-procedural	4/628 (0.64)	3/173 (1.73)	0/104 (0.00)	3/277 (1.08)	1/351 (0.28)	0.3258
Post-procedural	2/628 (0.32)	0/173 (0.00)	0/104 (0.00)	0/277 (0.00)	2/351 (0.57)	0.5062
Cardiac avulsion or tear	6/628 (0.96)	4/173 (2.31)	1/104 (0.96)	5/277 (1.81)	1/351 (0.28)	0.0924
Vascular avulsion or tear	7/628 (1.11)	2/173 (1.16)	1/104 (0.96)	3/277 (1.08)	4/351 (1.14)	1.0000

IQR, interquartile range.

There was no significant difference in procedure-related major complications including death (2.9% vs. 2.0%; P = 0.4664), procedure-related deaths (1.1% vs. 0.9%; P = 1.0000), cardiac avulsion or tear (1.8% vs. 0.3%; P = 0.0924), and vascular avulsion or tear (1.1% vs. 1.1%; P = 1.0000).

However, there were significantly more intra-procedure-related major complications including death in high-risk areas with 8 (2.9%) events compared and 2 (0.6%) events in the catheterization laboratory (P = 0.0259).

Patient preparation: anaesthesia and arterial lines

A general anaesthetic was given at the start of the case in 1360 (38.7%) patients and 2150 (61.3%) patients had local anaesthesia or sedation at the start of the procedure. Patients undergoing a general anaesthetic at the start of the case were more likely to suffer procedure-related major complications including death (2.7% vs. 1.0%; P = 0.0001), including both intra-procedure (1.5% vs. 0.7%; P = 0.0238) and post-procedure complications (1.2% vs. 0.2%; P = 0.0004). Pre-operatively an arterial line was placed in 2051 (58.4%) patients but was not inserted in 1459 (41.6%) patients. Patients who had an arterial line placed pre-procedurally were more likely to suffer procedure-related major complications including death (2.1% vs. 1.0%; P = 0.0144), particularly intra-procedure-related major complications including death (1.4% vs. 0.6%; P = 0.0324).

Discussion

Appropriate risk stratification prior to TLE is essential to ensure complications are managed as efficiently as possible. This current analysis of the ELECTRA registry is the largest study to date of contemporary lead extraction in Europe with important findings based on centre volume and experience.

The main findings are that:

• a successful procedure was more likely to occur with cardiologists as the primary operator in HiV centres (≥30/year);

• procedure-related deaths were more likely to occur when TLE’s were undertaken by primary operator cardiologists in LoV centres; and

• overall, there was no significant difference in procedure-related major complications including death when procedures were undertaken in a high-risk environment, combining the operating room and hybrid theatre, and the catheterization laboratory.

Centre volume/experience

Guidelines recommend that TLE operators should perform at least 40 extractions as the primary operator involving at least 30 procedures to have adequate training in TLE and to maintain competency that at least 20 leads are extracted in at least 15 procedures per year.^1,8 Clinical outcomes and success are influenced by operator and centre experience.^5,7–9 Byrd et al.⁹ showed in a prospective registry of 2338 patients undergoing extraction that the risk of any complication was associated with operators who had undertaken <50 prior extractions. The ELECTRa registry showed HiV centres had a significantly lower all-cause in-hospital major complications (2.4% vs. 4.1%; P = 0.0146) but the rates of procedure-related major complications including death were similar (1.5% vs. 2.4%; P = 0.1103).⁵ Overall, it showed 66% of in-hospital mortality were not procedure-related. In the current analysis, we have shown that procedures carried out by primary operator cardiologists in LoV centres were less likely to be successful (93.5% vs. 97.1%; P < 0.0001) and more likely to be complicated by procedure-related deaths (1.1% vs. 0.4%; P = 0.0417). Primary operator cardiologists in LoV centres were associated with procedure-related major complications including death (OR 1.858, 95% CI 1.007–3.427; P = 0.0475) and procedure-related deaths (OR 2.877, 95% CI 1.034–8.005; P = 0.0430) including intra-procedure deaths (OR 4.887, 95% CI 1.218–19.606; P = 0.0252). These findings underline the importance of experience in TLE, particularly complex cases that are at a higher risk and as such may be more appropriate for an experienced HiV operator and centre.

Identification of high-risk cases

The identification of high-risk cases pre-procedurally enables extraction procedures to be undertaken in a high-risk environment with appropriate expertise to manage potential complications. Several characteristics are associated with a higher risk of procedural-related complications; age, female gender, body mass index <25 kg/m², New York Heart Association Class III–IV, chronic kidney disease, severe left ventricular systolic impairment, infection, prolonged lead dwell time, use of powered sheaths, and femoral approach.^5,10–13 In this analysis, there was no significant difference in procedure-related major complications including death between a high-risk environment and the catheterization laboratory. Interestingly, many cases with high-risk features including being elderly, New York Heart Association Class III–IV, chronic kidney disease, infectious indication for TLE, and use of powered sheaths were more likely to have procedures carried out in the catheterization laboratory rather than the operating room and hybrid theatre. This patient allocation was especially true for HiV centres. However, LoV centres were more likely to allocate patients with high-risk characteristics including; lower body mass index, infectious indication for TLE, systemic infection, and use of powered sheaths, to a high-risk environment.

Patients who underwent TLE by a cardiologist with a cardiothoracic surgeon present, pre-procedural general anaesthesia, and arterial line insertion were more likely to suffer procedure-related major complications including death. The presence of a cardiologist and cardiothoracic surgeon was independently associated with procedure-related major complications including death (OR 3.094, 95% CI 1.789–5.352; P = 0.0001). This is likely to relate to the fact that such patients had a more prolonged lead dwell time suggesting centres were able to identify very high-risk cases pre-procedurally, underlined by the fact they were carried out in a high-risk environment in 72.8% of cases, thus enabling appropriate monitoring and expertise to be present. Likewise lead dwell time was significantly longer in patients who were allocated to extractions in high-risk settings, in both HiV and LoV centres. Risk stratification remains challenging and several metrics have been developed to help identify high-risk patients and ensure their TLE is carried out in the correct setting with appropriate resources available.^13,14 Further work is needed in this area to validate these scores and will be increasingly important given rising rates of TLE.

Limitations

This study is subject to the same limitations inherent with observational studies. However, dedicated data monitors were used to oversee data entry and ensure the accuracy of data.

There is a considerable inclusion bias in this study since participation was voluntary and not all centres in Europe were included. Although centres were dichotomized into HiV and LoV it should be noted that there was no documentation of individual operator experience and volume. It is, therefore, possible that there may be LoV operators undertaking TLE in HiV centres and vice versa. Given the relatively low number of cardiothoracic surgeons as primary operators in this registry, their outcomes should be interpreted with caution. Additionally, the prior experience of individual operators was not reported. The catheterization laboratory was considered a lower risk environment for TLE but the availability of surgical assistance or tools necessary to manage complications was not reported.

Conclusions

Transvenous lead extraction performed by primary operator cardiologists in LoV centres were more likely to be complicated by procedure-related deaths and less likely to be successful. Patients with characteristics placing them at a higher risk of complications require a comprehensive risk assessment using a multidisciplinary approach to appropriately allocate them to an extraction environment with the relevant expertise present. Those deemed very high risk may be more appropriate for a HiV extraction centre.

Supplementary material

Supplementary material is available at Europace online.

Acknowledgements

EORP Oversight Committee, Registry Executive Committee of the EURObservational Research Programme (EORP). Data collection were conducted by the EORP department from the ESC by Myriam Glemot as Project Officer, Maryna Andarala as Data Manager. Overall activities were coordinated and supervised by Doctor Aldo P. Maggioni (EORP Scientific Coordinator). Specific data used within this manuscript is unavailable.

Funding

The following companies have supported the study: Boston Scientific, Cook Medical, Medtronic, Spectranetics, and Zoll. The study was supported by the Wellcome/EPSRC Centre for Medical Engineering [WT203148/Z/16/Z]. The research was supported by the National Institute for Health Research (NIHR) Biomedical Research Centre based at Guy’s and St Thomas’ NHS Foundation Trust and King’s College London. The views expressed are those of the author(s) and not necessarily those of the NHS, the NIHR, or the Department of Health.

Conflict of interest: Outside of the submitted work, B.S.S. is funded by a project grant from the NIHR, and J.G. has received project funding from Rosetrees Trust. J.G., M.E., and V.M. have received fellowship funding from Abbott, outside of the submitted work. C.K. has presented on behalf of advised and performed studies with Spectranetics/Philips, outside of the submitted work. J.C.D. has received minor honoraria from Philips for lectures and consulting, outside of submitted work. A.A. is a consultant to Boston Scientific, Backbeat, Biosense Webster, Cardiac, Corvia, Daiichi-Sankyo, EBR Systems, Medtronic, Merit, Microport CRM, Philips, and V-Wave; he received speakers’ fee from Daiichi-Sankyo, Boston Scientific, Biosense Webster, Medtronic, Microport CRM, and Philips; he participated in clinical trials sponsored by Boston Scientific, EBR Systems, Philips; he reports intellectual properties with Boston Scientific, Biosense Webster, and Microport CRM. Outside of the submitted work. K.H.K. reports grants and personal fees from St. Jude Medical, Biosense Webster and Medtronic, outside of the submitted work. C.A.R. receives research funding and/or consultation fees from Abbott, Medtronic, Boston Scientific, Spectranetics, and MicroPort, outside of the submitted work. All other authors have no conflict of interest to declare.

Author notes

Members of ELECTRa Investigators Group are listed in Supplementary material online, Appendix S1.