https://orcid.org/0000-0002-4106-9771
Figure demonstrating the current knowledge with post-operative AF being responsible for an increased risk of long-lasting AF, mortality, and stroke. The current study demonstrates that in cardiac and non-cardiac surgery patients there is a significantly increased risk of heart failure hospitalization in those with POAF and those with prior AF. There are a number of potential mechanisms and management strategies that require further research including improved risk stratification and peri- and post-operative interventions. AF: atrial fibrillation; POAF: post-operative atrial fibrillation; CHF: congestive heart failure; HR: hazard ratio; CI: confidence interval; HFpEF: heart failure with preserved ejection fraction; HFrEF: heart failure with reduced ejection fraction.
This editorial refers to ‘Post-operative atrial fibrillation and risk of heart failure hospitalization’, by P. Goyal et al.,https://doi.org/10.1093/eurheartj/ehac285.
Post-operative atrial fibrillation (POAF) is a well-recognized consequence of surgery. The incidence of POAF following cardiac surgery has been reported to be between 20% and 40%1 and following non-cardiac surgery between 1% and 15%.2 POAF is associated with significant short-term morbidity and long-term elevations in the risk of a multitude of adverse cardiovascular outcomes including recurrent AF, stroke, myocardial infarction, and mortality;2,3 however, data on heart failure (HF) are more limited.
It is in this context that we read with interest the work by Goyal and colleagues in this issue of the European Heart Journal. The authors conducted a large retrospective cohort study that utilized data from an all-payer administrative claims database from 11 states in the USA. Surgical hospitalizations were identified using Medicare Severity-Diagnosis Related Group codes, and AF diagnoses and subsequent HF hospitalizations were identified using ICD-10 codes. Patients with codes for HF on the index presentation or previous hospitalization or who died during the index admission were excluded from the analysis, and POAF was defined as a new AF code on discharge. In a sample of 3 006 390 patients undergoing surgery, 38 128 (1.3%) had a first diagnosis of AF on hospital discharge and 201 101 (6.7%) had previously been diagnosed with AF. After controlling for available data on comorbidities, patients with post-operative AF after cardiac surgery (14 365; 18%) had a significant 33% higher risk of HF hospitalization over 1.7 years of follow-up, which was attenuated but remained significant after excluding hospitalizations occurring during the first-year post-surgery (15% higher risk; 95% CI: 1–31%). For those who underwent non-cardiac surgery, POAF was associated with a significant two-fold elevation in HF hospitalizations and a 1.5-fold elevation in hospitalizations for HF occurring more than one year after surgery. Consistent with prior studies, previously diagnosed AF was strongly associated with subsequent HF hospitalization in both surgical groups,4, 5 and POAF and prior AF were both associated with higher risks of mortality.2,3,5
These data add to a growing body of literature suggesting that POAF is not just a transient response to surgery but may be reflective of underlying atrial and myocardial structural changes that not only predispose to the acute AF event but to other potentially related adverse cardiovascular events, such as HF hospitalization. Recent studies in cardiac surgery patient populations have also reported significant long-term elevations in risk of HF hospitalizations in patients with POAF.4, 6 A recent propensity-matched analysis involving 12 227 patients undergoing cardiac surgery demonstrated a similar 15% increase in the adjusted risk of HF readmissions over up to 5-years of follow-up in patients with POAF.4 Similar findings on HF admissions were also reported in a single center in Taiwan over a median of 9 years of follow-up.6 The study in this week’s EHJ adds to this literature by demonstrating that the associations between POAF and subsequent HF hospitalizations also extend to patients undergoing non-cardiac surgery, and perhaps the magnitude of the risk might even be greater in these patients.
What might be the mechanism as to how POAF might lead to heart failure years later even among non-cardiac surgery patients? First, much of the association may be mediated by recurrent and/or subclinical AF leading to subsequent HF. Patients with POAF have a greater risk for subsequent AF,4 and there are data to suggest that the risk of recurrent AF may be higher in patients undergoing non-cardiac vs. cardiac surgery.7 Patients who present with POAF may also have established, undetected AF, which is subsequently first diagnosed at the time of surgery. Second, the predisposing substrate for both AF and HF develop over years,8 and often it can be difficult to tease apart which came first. Given the number of shared risk factors between the two conditions, such as hypertension, diabetes, ischemic heart disease, and valvular heart disease, there is likely significant overlap in the development of the predisposing substrate in both the atria and the ventricle. Thus, POAF may be a marker of both developing disease processes.
It is important to note, however, that there are some limitations of the presented data that need to be considered. First, at least part of the observed association between POAF and HF could be due to confounding by patient characteristics and/or associated shared risk factors, such as smoking and alcohol intake, which were not controlled for in this administrative database. Second, the role of recurrent AF as a mediator of the observed association between POAF and HF was not considered, which would have provided insight regarding mechanism and potential clinical management. Third, the ability to accurately detect incident AF can be difficult within US hospital claims data, and it is feasible that patients were previously diagnosed in the outpatient setting. Finally, as with most claims data, granular data regarding prior cardiac evaluations, and in particular cardiac monitoring and imaging, were not available. Thus, the study was not able to determine whether there was clinically detectable evidence of atrial and/or ventricular myopathy at the time of the POAF that proceeded the HF diagnosis. Increased left atrial diameter and reduced left ventricular ejection fraction have been associated with an increased incidence of POAF,9 and both could predispose to subsequent HF.
To conclude, what are the potential implications of these findings? The present study and other recent studies highlight the burden of POAF on morbidity, mortality, and the healthcare system. Currently, preoperative evaluation and risk prediction models focus primarily on detection and optimal management of coronary artery disease,5 and these data suggest that a greater focus on heart failure and AF, particularly in non-cardiac patients, may improve post-operative outcomes. Once POAF is documented, adopting a strategy of early rhythm control may lower risk for subsequent adverse cardiovascular outcomes including HF as was documented for newly diagnosed AF in the Early Treatment of Atrial Fibrillation for Stroke Prevention Trial (EAST-AFNET 4) study.10 Conversely, screening for HF and optimizing targeted drug therapies may also improve the likelihood of maintaining sinus rhythm.11 Additionally, in those with new-onset AF, optimal levels of modifiable risk factors including obesity, hypertension, smoking, and diabetes have been demonstrated to significantly reduce the risk of recurrent AF;12–14 which in turn may also reduce the risk of developing HF.15 Intervention with early initiation of therapies and comprehensive risk factor modification could manage key shared risk factors such as obesity, hypertension, and diabetes in turn addressing what may be the underlying substrate for POAF and HF. The potential benefits of early risk factor management in individuals undergoing surgery requires evaluation.
Finally, a better understanding of the ‘at risk’ cohort, through an increased knowledge and understanding of the underlying substrate for POAF and HF is needed to further reduce rehospitalization and mortality post-surgery. The latter will require studies with more granular patient-level data beyond that available within claims databases to be able to properly assess the mechanisms underlying the link between POAF and HF. Having patient-specific data, inclusive of imaging and complete risk factor and comorbidity profiles, may provide the tools needed to evaluate some of the ambiguities that hinder progress on reducing the burden of POAF and its associated adverse outcomes. With a greater understanding of patient’s full risk factor profile, we may advocate for early aggressive intervention at the initial manifestation of POAF, to improve outcomes and reduce rehospitalization following cardiac and non-cardiac surgery.
References
Author notes
The opinions expressed in this article are not necessarily those of the Editors of the European Heart Journal or of the European Society of Cardiology.
Conflict of interest: None declared.
