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Page 2 of 14 Obeid et al. Vessel Plus 2022;6:43 https://dx.doi.org/10.20517/2574-1209.2021.136

INTRODUCTION
Atrial fibrillation (AF) is the most common arrhythmia, and its pathophysiology appears to be intertwined
[2]
[1]
with that of heart failure (HF) , as one diagnosis may predispose to the other diagnosis . AF affects about
50% of New York Heart Association (NYHA) class IV patients with HF; its prevalence in HF patients
[3]
increases with increasing HF disease severity . Increased distention and remodeling of the HF patients’
[4]
atria disrupt the myocardial conduction pathways and may lead to subsequent AF .
Approximately 6.2 million adults in the United States (US) have been diagnosed with HF, according to the
Centers for Disease Control. Advanced HF patients not responding to maximal medical therapy ultimately
require heart transplantation. Due to a shortage of donor hearts (i.e., only 3597 heart transplants performed
[5]
with 4086 newly listed US-based candidates during 2019 ), over 5000 HF patients were placed on
ventricular assist devices in 2000.

In general, HF patients’ survival has been continuously improving. For the patients ineligible to receive a
heart transplant, destination therapy using left ventricular assist devices (LVADs) has been used since the
1990s to improve end-stage HF patients’ outcomes . Further improvement in these LVAD patients’
[6]
outcomes was achieved with increased patient management experience, improved patient selection and
coordination of intensive post-discharge follow-up programs; additionally, there have been substantial
technological LVAD advancements since the early 2000s [7-10] .

To provide temporary assistance or to avoid cardiopulmonary deficit, intra-aortic balloon pumps,
percutaneous ventricular assist devices/Impella (Abiomed, Danvers, Massachusetts), or veno-arterial
extracorporeal membrane oxygenation (ECMO) have been used to treat patients with life-threatening
medically refractory cardiogenic shock in an acute care setting. Patients treated with ECMO had improved
30-day survival by 33% compared to patients treated with intra-aortic balloon pumps . However, during
[11]
the past decade, from 2003 to 2014, ECMO patients’ outcomes have remained grim, with survival to
discharge estimated at 50% [12,13] .

Within the LVAD population, AF has been reported with divergent results regarding its effect on patient
outcomes. Based on the very limited literature to date, AF appears in 30%-50% of patients undergoing
LVAD placement [14-16] . However, it is unclear whether AF is a pre-LVAD risk factor or a post-LVAD
complication leading to the cascade for worse post-LVAD outcomes. To date, AF in LVAD patients has not
been well characterized. For ECMO patients, similarly, AF as an impediment to myocardial recovery has
not been evaluated. Given this “gap” in AF knowledge, this review raises crucial questions intended to target
future investigations, as well as to identify novel opportunities to improve mechanical circulatory assist
device patients’ quality of care.

METHODS
Exposing key areas of uncertainty and identifying opportunities for future research, the available literature
related to AF in patients with mechanical circulatory support has been summarized. Two reviewers (Yaligar
A and Obeid JM) conducted a rigorous literature search of indexed articles in PubMed from inception
through August 2021. The search strategy included relevant MeSH terms and keywords, including
mechanical circulatory support devices, clinical risk factors, and adverse outcomes. A detailed search
strategy is available in the online Supplementary Table 1. Further, Web of Science was used to perform a
“backwards” citation search to capture additional relevant references. Following our detailed search strategy,
we obtained 333 articles; of these, 298 were excluded due to a lack of AF incidence rates or multivariable
model results.