Bridging patients in cardiogenic shock with a paracorporeal pulsatile biventricular assist device to heart transplantation—a single-centre experience

Abstract

OBJECTIVES

We evaluated the outcome of patients in cardiogenic shock receiving a paracorporeal pulsatile biventricular assist device as a bridge to transplantation.

METHODS

We performed a retrospective single-centre analysis of all patients who received a Berlin Heart Excor^® at our institution between 2004 and 2019.

RESULTS

A total of 97 patients (90 adults, 7 paediatric) were analysed. Eighty-four patients were in Interagency Registry for Mechanically Assisted Circulatory Support level 1 (80 adults, 4 paediatric). Diagnoses were dilated cardiomyopathy (n = 41), ischaemic cardiomyopathy (n = 17) or myocardial infarction (n = 4), myocarditis (n = 15), restrictive cardiomyopathy (n = 2), graft failure after heart transplant (n = 7), postcardiotomy heart failure (n = 5), postpartum cardiomyopathy (n = 3), congenital heart disease (n = 1), valvular cardiomyopathy (n = 1) and toxic cardiomyopathy (n = 1). All patients were in biventricular heart failure and had secondary organ dysfunction. The mean duration of support was 63 days (0–487 days). There was a significant decrease in creatinine values after assist device implantation (from 1.83 ± 0.79 to 1.12 ± 0.67 mg/dl, P = 0.001) as well as a decrease in bilirubin values (from 3.94 ± 4.58 to 2.65 ± 3.61 mg/dl, P = 0.084). Cerebral stroke occurred in 16 patients, bleeding in 15 and infection in 13 patients. Forty-eight patients died on support, while 49 patients could be successfully bridged to transplantation. Thirty-day survival and 1-year survival were 70.1% and 41.2%, respectively.

CONCLUSIONS

A pulsatile biventricular assist device is a reasonable therapeutic option in cardiogenic shock, when immediate high cardiac output is necessary to rescue the already impaired kidney and liver function of the patient.

Biventricular assist device, Heart transplant, Cardiogenic shock, Pulsatile ventricular assist device

INTRODUCTION

Mechanical circulatory support (MCS) is an established therapy for advanced heart failure. Continuous-flow pumps as left ventricular assist devices (LVADs) have the advantage that patients can be bridged to heart transplantation while leading almost a normal life at home with an acceptable quality of life and a 1-year survival of 82% [1]. However, a subgroup of patients with advanced biventricular heart failure is referred too late and is already in beginning cardiogenic shock with secondary organ failure. LVAD implantation alone or LVAD implantation in combination with temporary right ventricular assist device (RVAD) does not lead to favourable outcomes in this situation [2, 3]. Immediate mechanical support of both ventricles becomes necessary to overcome cardiogenic shock and multiorgan failure.

The purpose of this study was to evaluate the outcome of patients in beginning cardiogenic shock [Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS) level 1 and 2 patients] at our centre who received a paracorporeal pulsatile biventricular assist device (BVAD) as a bridge to heart transplantation.

PATIENTS AND METHODS

Ethics statement

The local university Ethics Committee approved this scientific review (approval code 20-0399). All transplants were carried out in strict compliance with the International Society for Heart and Lung Transplantation (ISHLT) ethics statement (approved 2007 and updated 2014, www.ishlt.org). The principles of the Declaration of Helsinki formulated by the World Medical Association and the Declaration of Istanbul have been adhered to.

We conducted a nonrandomized, retrospective study of all patients who received a Berlin Heart Excor^® BVAD between 2004 and 2019 at Ludwig Maximilian University. The study cohort was classified into INTERMACS level 1 and 2 patients. Paediatric patients as well as INTERMACS level 2 patients were excluded from the study.

The BVAD was implanted as a bridge to transplantation, and all patients were screened for absolute contraindications against heart transplant before the emergency VAD implantation. Criteria for biventricular support in non-extracorporeal life support (ECLS) patients were determined using a combination of echocardiography, right heart catheterization (often bedside using pulmonary artery catheter) and laboratory values:

1. severe tricuspid regurgitation particularly in the absence of severe pulmonary hypertension,

2. right atrial pressure >15mmHg, reduced right ventricular ejection fraction (RV-EF) and reduced tricuspid annular plane systolic excursion (<1.5 cm) and

3. signs of end-organ dysfunction (kidney: oliguria, need for haemofiltration, elevated creatinine values; liver: elevated bilirubin and liver enzyme values).

In ECLS patients, the need for biventricular support was determined after a failed ECLS-weaning attempt (unsatisfactory contractility response to inotropes on echocardiography).

A special indication for biventricular support was refractory ventricular tachycardia despite antiarrhythmic medication and failed ablation attempt.

The decision to implant a Berlin Heart Excor^® BVAD was made only after the patient was seen as a potential candidate for heart transplantation by our interdisciplinary transplant team. A complete evaluation for heart transplantation, however, could not always be performed before BVAD implantation due to the urgent need of MCS.

Berlin Heart Excor^® ventricular assist device

The paracorporeal pulsatile Excor^® device is available in different pump sizes and with different valves (polyurethane or mechanical valves). In this study, 80-ml pumps were used to support the left ventricle and 60-ml pumps were used to support the right ventricle in all adult patients. In paediatric patients, pump size was chosen according to the size and weight recommendations of the company with 10 ml being the smallest ventricle. From 2004 to 2014 we used ventricles with polyurethane valves and from 2014 on ventricles with mechanical valves were used in adults. They were checked 3 times a day and exchanged at the bedside when significant thrombi were visible.

Surgery

The 4 cannulae were implanted via a median sternotomy on full cardiopulmonary bypass with the heart beating and intermittently fibrillating (for insertion of the left ventricular apex cannula). When ECLS was cannulated in the femoral vessels for preop optimization of the patient, these cannulae were used for cardiopulmonary bypass which gave more room for BVAD implantation in the chest. The operating field was flooded with CO₂. Cardioplegia to arrest the heart was only given when large amounts of thrombotic material were present in the left ventricular cavity that had to be evacuated under optimal visibility. The order of cannula implantation was left ventricular apex, right atrium, pulmonary artery and aorta. Interrupted pledgeted sutures were used for the left ventricular and right atrial cannulae, running sutures for the pulmonary artery and aorta. In restrictive cardiomyopathy patients with very small left ventricular cavities, a left atrial cannula was implanted instead of a left ventricular cannula to avoid suction phenomena. Fibrin glue was applied to all anastomoses. After careful deairing of all cannulae, they were connected to the ventricles outside the chest (Fig. 1). The Excor^® device was started and cardiopulmonary bypass was weaned slowly. Protamine was given and haemostasis achieved with the help of blood products.

Figure 1:

Berlin Heart EXCOR^® biventricular assist device. Picture left: head, right: feet (surgeon’s view).

GoreTex™ Pericardial Membrane (GORE-TEX; WL Gore & Associates, Flagstaff, AZ, USA) was used to cover all cannula and the heart to avoid adhesions as much as possible, which facilitated reentring the chest for heart transplantation. Both pleural spaces were always opened and drained to prevent pericardial tamponade and to drain pleural effusions that are usually present in those decompensated patients. In the early era of our study (2004–2011) the chest was often left open for 24 h to prevent tamponade. Recently, we are closing it in the usual fashion primarily.

Anticoagulation

Anticoagulation was started on postoperative day 1 (24 h after surgery) after cessation of perioperative bleeding with continuous intravenous heparin controlled by partial thromboplastin time (PTT) and was switched to vitamin K antagonist (target international normalized ratio (INR) = 3–3.5) after patients had been extubated. Anti-platelet therapy with aspirin (100 mg/day, weight adapted in paediatric patients) and clopidogrel (75 mg/day) was started on postoperative days 2 and 3, respectively, and controlled by thrombelastography.

Outcome parameters

Perioperative data were taken from medical records. Patients were analysed for their preoperative state (age, sex, renal and liver function, heart function). Survival, adverse events, renal and liver function before and after BVAD implantation and outcome after heart transplant were analysed.

Statistical analysis

Continuous variables are presented as the mean ± standard deviation, with categorical variables summarized by frequency and percentage. Depending on normal distributions Student’s t-test or Mann–Whitney–Wilcoxon test was used to compare continuous variables. The Kolmogorov–Smirnov test was used to assess normal distribution. Chi-square test was used to compare categorical variables. Cox-regression analysis was applied to identify the associations of certain variables on 30-day survival after BVAD implantation like age, sex, body mass index (BMI), indication, laboratory values and dialysis before BVAD.

Paired t-test was used to compare changes of kidney and liver function before and after BIVAD implantation.P < 0.05 was considered statistically significant. Data were statistically analysed by SPSS version 24.0 (IBM SPSS, Armonk, NY, USA) statistical software.

RESULTS

Patient characteristics

From 97 patients with BVAD implantation, 84 patients (86.6%) were identified INTERMACS level 1 (critical cardiogenic shock) and 13 patients (13.4%) as INTERMACS level 2 (progressive decline on inotropic support), respectively. Paediatric patients (n = 7) as well as INTERMACS level 2 patients were excluded from further statistical analysis as depicted in Fig. 2.

Figure 2:

Description of the study cohort and classification. BVAD: biventricular assist device.

All patients required biventricular MCS due to the beginning of end-organ failure despite therapy with inotropes or short-term MCS (see Fig. 3). In 20 patients (20.6%), the BVAD implantation was a redo procedure after prior sternotomy for coronary artery bypass grafting, valve operations or previous heart transplant. Primary diagnoses are shown in Fig. 4.

Figure 3:

Type of mechanical circulatory support before biventricular assist device implantation.

Figure 4:

Diagnoses that led to biventricular heart failure. AMI: acute myocardial infarction; CHD: congenital heart disease; DCM: dilative cardiomyopathy; ICM: ischaemic cardiomyopathy; RCM: restrictive cardiomyopathy.

Table 1 shows the demographics and preoperative data of the whole cohort (adult and paediatric). All patients had severe biventricular dysfunction with pulmonary hypertension and elevated filling pressures, which led to congestion and pneumonia in most cases. All patients presented with beginning end-organ failure, particularly impaired kidney and liver function. A total of 26 patients (32.5%) were in renal failure with the need for haemodialysis before BVAD implantation.

Table 1:

Demographics and preoperative values before biventricular assist device implantation (whole cohort)

Gender (male/female)	77/20
Adult patients (>18 years)	90
Paediatric patients (0–18 years)	7
Age adult patients, median (range)	48.6 (20–66)
Age paediatric patients, median (range)	14.5 (0–17)
INTERMACS level 1/2	84/13
Prior MCS	60
Re-sternotomy for BVAD implantation	20
Cardiac index (l/min/m2), mean ± SD	1.7 ± 0.6
LVEF (%), mean ± SD	16.2 ± 8.0
LVEDP (mmHg), mean ± SD	29.9 ± 6.1
PAPmean (mmHg), mean ± SD	40.9 ± 8.5
CVP (mmHg), mean ± SD	18.1 ± 6.5
Creatinine (mg/dl), mean ± SD	1.8 ± 0.8
Bilirubine (mg/dl), mean ± SD	3.6 ± 4.2
Pro BNP (pg/ml), mean ± SD	19 265 ± 22 009
Lactate (mmol/l), mean ± SD	2.3 ± 2.3
Leukocytes (g/l), mean ± SD	13.4 ± 5.5
CRP (mg/dl), mean ± SD	7.3 ± 7.0

BVAD: biventricular assist device; BNP: brain natriuretic peptide; CVP: central venous pressure; CRP: C reactive protein; INTERMACS: Interagency Registry for Mechanically Assisted Circulatory Support; LVEDP: left ventricular enddiastolic pressure; LVEF: left ventricular ejection fraction; MCS: mechanical circulatory support; PAP: pulmonary arterial pressure; SD: standard deviation.

Survival

The mean duration of support was 63.6 ± 77.9 days (median = 37 days, range 0–487 days) with 7 patients being on the device for >6 months. Forty-eight patients (45 adult, 3 paediatric) died on support, while 49 patients (45 adult, 4 paediatric) could be successfully bridged to heart transplantation. Of the 60 patients who had MCS prior to BVAD implantation, 32 died and 28 could be successfully bridged to transplant. All patients on BVAD remained in the hospital until heart transplantation. Thirty-day survival and 1-year survival after BVAD implantation of the whole cohort were 70.1% and 41.2%, respectively [adult (n = 90): 70.0% and 40.0%; paediatric (n = 7): 71.4% and 57.1%].

We performed statistical analysis on all adult patients in INTERMACS level 1 to get a uniform study cohort (n = 80, Fig. 2). Of the 80 adult INTERMACS 1 patients, 37 could be bridged successfully to transplantation, while 43 did not survive. Of these, 12 had a thromboembolic complication on BVAD (8 intracerebral bleeding, 2 stroke, 1 pulmonary embolism, 1 intestinal bleeding) while 31 did not recover from end-organ dysfunction on support and died from multiorgan failure or sepsis. Thirty-day survival and 1-year survival in this group were 70% and 36.3%, respectively. Higher BMI was independently associated with higher risk for 30-day-mortality (BMI: P = 0.041; hazard ratio 1128; confidence interval 1015–1335) while controlling for sex, age, indications for BVAD, revision surgery, CRP, leukocytes, bilirubin and creatinine in regression analysis (P = 0.039).

Table 2 shows the characteristics of adult INTERMACS level 1 patients undergoing BVAD implantation and risk factors for mortality before heart transplantation. We were able to identify 4 significant risk factors for mortality:

Table 2:

Characteristics of adult Interagency Registry for Mechanically Assisted Circulatory Support 1 patients undergoing biventricular assist device implantation

	All (n = 80)	Successfully bridged to HTx (n = 37)	Did not survive bridge to HTx (n = 43)	P-Value
Age (years)	46.0 ± 12.0	44.0 ± 12.7	47.7 ± 11.2	0.170
Sex (male), n (%)	64 (80.0)	30 (81.1)	34 (79.1)	0.823
BMI (kg/m2)a	25.2 ± 4.5	23.7 ± 2.9	26.7 ± 5.3	0.003
Indications for BVAD				0.261
Dilative cardiomyopathy	33 (41.3)	17 (45.9)	16 (37.2)
Ischaemic cardiomyopathy	15 (18.8)	9 (24.3)	6 (14.0)
Myocarditis	12 (15.0)	3 (8.1)	9 (20.9)
Othersb	20 (25.0)	8 (21.6)	12 (27.9)
Preoperative laboratory findings
Creatinine, mg/dl	1.8 ± 0.8	1.8 ± 0.8	1.9 ± 0.8	0.652
Bilirubin, mg/dl	3.9 ± 4.6	3.3 ± 4.4	4.5 ± 4.7	0.214
C-reactive protein, mg/dl	7.8 ± 7.3	6.6 ± 5.9	9.0 ± 8.3	0.169
leucocyte blood count (g/l)	13.5 ± 5.7	12.0 ± 4.2	14.7 ± 6.5	0.040
Left ventricular ejection fractionc (%)	16.0 ± 8.2	14.7 ± 5.4	17.3 ± 10.1	0.183
Pulmonary hypertension,d  n (%)	29 (93.5)	13 (92.9)	16 (94.1)	0.887
PAP (mmHg), mean ± SD	41.5 ± 8.5	41.8 ± 7.4	41.3 ± 9.5	0.875
Dialysis before BVAD,e  n (%)	23 (28.8)	6 (17.6)	17 (43.6)	0.017
Resternotomy for BVAD implantation	15 (18.8)	2 (5.4)	13 (30.2)	0.005
Complications
Bleeding, n (%)	12 (15.0)	3 (8.1)	9 (20.9)	0.109
Infection, n (%)	10 (12.5)	4 (10.8)	6 (14.0)	0.672
Re-OP, n (%)	34 (42.5)	13 (35.1)	21 (48.8)	0.216

Data are presented as mean ± standard deviation and number and percentage, respectively.

a

Available in 71 patients (36/35).

b

Restrictive, toxic, congenital, arrhythmogenic ventricular cardiomyopathy; acute myocardial infarction, post HTx, post-partum.

c

Available in 68 patients (34/34).

d

Available in 31 patients (14/17).

e

Available in 73 patients (34/39).

BMI: body mass index; BVAD: biventricular assist device; HTx: heart transplant; PAP: pulmonary arterial pressure; SD: standard deviation.

1. high BMI,

2. BVAD implantation as a reoperation (resternotomy),

3. high white count as a sign for infection/sepsis or inflammation and

4. renal failure with the need for haemodialysis before BVAD implantation.

Causes of death after BVAD implantation were multiorgan failure (n = 24), cerebral haemorrhage (n = 11), sepsis (n = 8), stroke (n = 3), pulmonary embolism (n = 1), intestinal bleeding and ischaemia (n = 1).

One-year survival after heart transplant from BVAD was 80% (10 patients died, 6 from sepsis, 3 from graft failure and 1 from bleeding after heart transplant). Eight patients became sensitized and developed HLA antibodies; however, none of them to a point where they became not transplantable. Two patients underwent a desensitization protocol with anti-CD20 antibody.

Adverse events

Thirty-four patients of the whole cohort were affected by the common VAD-related adverse events. Stroke occurred in 16 patients (16.5%) and bleeding (non-thoracic) in 15 patients (15.5%). Thirteen patients (13.4%) suffered from wound infections at the cannula exit site that required antibiotic therapy in addition to local wound care twice daily. No device infection that would have required surgical removal was seen. Forty-one patients (42.3%) had intrathoracic bleeding postoperatively that required re-exploration of the chest. Patients with prior sternotomy required more blood transfusions [an average of 16 packed red blood cells (250 ml each) vs 8 for patients without prior sternotomy]. Pump replacements due to thrombotic deposits were necessary in 40 patients (41.2%), in 15 patients more than once (Fig. 5). On average, the first pump replacement was necessary after 35.5 days. In 1 patient, thrombotic deposits on the right side led to a fatal pulmonary embolism. No device malfunction occurred during the study period.

Figure 5:

Adverse events after biventricular assist device implantation.

Recovery of secondary organs after BVAD implantation

The pulsatile BVAD was able to improve the impaired renal and liver function in adult INTERMACS 1 patients (n = 80): there was a significant decrease in creatinine values (from 1.83 ± 0.79 mg/dl before BVAD implantation to 1.12 ± 0.67 4 weeks after BVAD implantation, P = 0.001) as well as a decrease in bilirubin values (from 3.94 ± 4.58 mg/dl before BVAD implantation to 2.65 ± 3.61 mg/dl 4 weeks after BVAD implantation, P = 0.084, Fig. 6).

Figure 6:

Recovery of kidney and liver function in adult Interagency Registry for Mechanically Assisted Circulatory Support 1 patients: distribution of creatinine (A) and bilirubin (B) pre-biventricular assist device and 4 weeks post-biventricular assist device (box and whisker plots).

In the group of patients that were successfully bridged (n = 49) creatinine and bilirubin values had significantly dropped by the time of heart transplant [creatinine: 1.78 ± 0.79 mg/dl before BVAD to 1.25 ± 0.79 mg/dl at time of heart transplant (P = 0.001); bilirubin: 3.08 ± 4.05 mg/dl before BVAD to 1.29 ± 0.93 mg/dl at time of heart transplant (P = 0.006)].

Fifteen patients underwent transplant while still on dialysis. Sixteen patients required renal replacement therapy after transplant (8 of them permanent).

DISCUSSION

Continuous-flow LVADs have helped improve outcomes and quality of life of patients suffering from heart failure when compared to best medical therapy alone [4].

However, right heart failure is a huge challenge in LVAD therapy and its occurrence is associated with increased mortality and morbidity [5]. The use of a temporary RVAD after LVAD implantation shows inferior outcomes compared to planned BVAD implantation [3, 6]. If right ventricular recovery is to be expected, the temporary RVAD should go in along with the LVAD so that RV recovery can begin right away. The use of 2 continuous-flow pumps as a BVAD has been described [7, 8] as a more ‘advanced’ and modern option compared to the use of the bigger paracorporeal pulsatile BVAD that seems much more invasive. However, the use of 2 continuous-flow devices is complex and off-label. The pumps are controlled independently from each other, which makes predictions of systemic and pulmonary blood flow almost impossible. Arabía et al. have published their experience with 38 patients on continuous-flow BVAD (continuous-flow LVAD + off-label LVAD in right sided position). The 1-year survival in this cohort was 62%; however, the patients were not as sick as in our cohort. Preimplant data show lower cardiac output and higher values of creatinine, bilirubin and central venous pressure in our patients [9]. The second annual ISHLT Mechanically Assisted Circulatory Support registry shows superior 1-year survival rates in pulsatile BVAD (57.8%) versus continuous-flow BVAD (53.1) versus pulsatile total artificial heart (47.8%) [10]. We could confirm these results in our centre and stopped using continuous-flow pumps in biventricular heart failure, at least for bridge to transplant and INTERAMACS level 1 patients. Another recent small study using the continuous-flow Heart Mate 3 device in a biventricular configuration showed excellent 1-year survival (>90%); however, 11 of the 12 patients were INTERMACS level 2 and, therefore, not as critically ill as our cohort before VAD implantation [11].

The Excor^® paracorporeal BVAD provides full pulsatile haemodynamic support of the circulation. This can be easily monitored on the device and adjusted if necessary. Compared to continuous-flow devices, which show only a calculated flow, the Excor^® provides the real cardiac output as a product of stroke volume (size of the pump) and pump rate. A pulsatile BVAD can even generate a higher-than-normal cardiac output (e.g. rate of 125/min to generate a cardiac output of 10 l/min using an 80 ml pump) that is necessary to overcome pneumonia and sepsis that was present in our cohort as shown by the elevated C reactive protein (CRP) and white count preoperatively. Postoperative management of these very sick patients is facilitated, and their organisms recover quite well (within a period of 4 weeks) preconditioning them for the following heart transplantation. It seems, however, that overweight patients recover worse from cardiogenic shock and sepsis, even when supported with a pulsatile BVAD. In addition, when the BVAD implantation requires a resternotomy, the chance of survival is worse in adults, which can be easily explained by the increased complexity of the case and the additional blood transfusions that are usually required in this scenario for bleeding due to adhesions. Reoperation was also defined as a risk factor for death after LVAD implantation alone in the latest INTERMACS report from 2019 [1].

A pulsatile VAD results in improved microcirculation and in a lower rate of gastrointestinal bleeding events compared to a continuous-flow device [12]. We were able to show that the implantation of the Excor^® BVAD in cardiogenic shock can be done with an acceptable rate of adverse events given the patient’s condition before the procedure. The rate of adverse events in continuous-flow BVADs is much higher [9]. Particularly, the rate of ischaemic strokes was low (16/97) due to the option to exchange the pump when thrombotic material becomes visible in the daily check of the paracorporeal device. This is a huge advantage compared to implantable continuous-flow devices. Device malfunction—a common problem when continuous-flow devices are implanted in a biventricular fashion [9]—did not occur in our series. We have shown that about half of these extremely sick patients can be bridged successfully to heart transplantation, although the majority of them already had short-term MCS devices in place and were in beginning renal and liver failure. The pulsatile biventricular support was able to recover the function of both kidney and liver within 4 weeks. The key question remains: How sick is too sick for this procedure? Based on our own experience and results from the ISHLT Mechanically Assisted Circulatory Support registry [10], we would be reluctant to implant a paracorporeal BVAD as a redo procedure (prior sternotomy) in an overweight patient who is in sepsis and renal failure.

Very encouraging results with the use of EXCOR^® BVAD have also been reported in 2 smaller series of INTERAMCS 1 patients by Schmack et al. [13] and Bartfay et al. [14] recently.

The 1-year survival after heart transplant was still 80% in our series. The main cause of death after heart transplant was sepsis in the early postoperative period.

Limitations

The results of our study are limited due to its retrospective single-centre character and the fact that the observations were made over a long period of time (2004–2020). To support our findings, a prospective multicentre BVAD-trial would be helpful.

CONCLUSION

In conclusion, a paracorporeal pulsatile BVAD provides good safety and acceptable results as a bridging device to heart transplantation in patients with cardiogenic shock and secondary organ failure. In this situation, the device is able to recover liver and kidney function and provides better results compared to the more complex and surgically demanding pulsatile total artificial heart [10].

In non-acute heart failure but gradually declining patients, interdisciplinary heart failure teams consisting of cardiologists and cardiac surgeons should try to refer them for VAD implantation or heart transplant before they are INTERMACS level 1. LVAD implantation should be performed whenever possible in an elective setting before BVAD implantation becomes necessary as an emergency procedure.

Funding

Sebastian Michel, Jürgen Hörer, Nikolaus Haas and Christian Hagl are members of the European EXCOR Paediatric Investigator Group (EEPIG) and received travel support from Berlin Heart.

Conflict of interest: Christian Hagl is on the scientific advisory board of Berlin Heart. The other authors report no conflict of interest.

Data Availability Statement

All relevant data are within the manuscript and its supporting information files.

Author contributions

Sebastian Michel: Conceptualization; Data curation; Formal analysis; Investigation; Methodology; Project administration; Supervision; Validation; Writing—original draft; Writing—review & editing. Stefan Buchholz: Data curation; Formal analysis; Investigation; Methodology; Validation; Writing—original draft. Joscha Buech: Data curation; Formal analysis; Methodology; Software. Tobias Veit: Data curation; Formal analysis; Methodology; Software; Validation; Writing—review & editing. Thomas Fabry: Data curation; Formal analysis; Methodology; Writing—review & editing. Jan Abicht: Formal analysis; Methodology; Writing—review & editing. Nikolaus Thierfelder: Data curation; Formal analysis; Investigation; Project administration; Writing—review & editing. Christoph Mueller: Data curation; Formal analysis; Methodology; Writing—review & editing. Laura Lily Rosenthal: Formal analysis; Methodology; Writing—review & editing. Jelena Pabst von Ohain: Data curation; Methodology; Validation; Writing—review & editing. Nikolaus Haas: Formal analysis; Supervision; Writing—review & editing. Juergen Hoerer: Formal analysis; Investigation; Validation; Writing—review & editing. Christian Hagl: Conceptualization; Formal analysis; Investigation; Project administration; Resources; Supervision; Writing—review & editing.

Reviewer information

European Journal of Cardio-Thoracic Surgery thanks Sai Kiran Bhagra, Can Yerebakan and the other, anonymous reviewer(s) for their contribution to the peer review process of this article.

ABBREVIATIONS

 
• BMI

  Body mass index

 
• BVAD

  Biventricular assist device

 
• ECLS

  Extracorporeal life support

 
• INTERMACS

  Interagency Registry for Mechanically Assisted Circulatory Support

 
• ISHLT

  International Society for Heart and Lung Transplantation

 
• LVADs

  Left ventricular assist devices

 
• MCS

  Mechanical circulatory support

 
• RVAD

  Right ventricular assist device

Author notes

†

Sebastian Michel and Stefan Buchholz contributed equally to this work.