Relative Contribution of Atrial Fibrillation to Outcomes of Patients With Cardiomyopathy Based on Severity of Left Ventricular Dysfunction

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In patients with left ventricular (LV) dysfunction, the risk of death or heart failure hospitalizations (HFHs) increases with worsening ejection fraction (EF). Whether the relative contribution of atrial fibrillation (AF) to outcomes is more pronounced in patients with worse EF is not confirmed. The present study aimed to investigate the relative influence of AF on the outcome of cardiomyopathy patients by severity of LV dysfunction. In this observational study, data from 18,003 patients with EF ≤50% seen at a large academic institution between 2011 and 2017 were analyzed. Patients were stratified by EF quartiles (EF<25%, 25%≤EF<35%, 35%≤EF<40%, and EF≥40%, for quartiles 1, 2, 3, and 4, respectively). and followed to the end point of death or HFH. Outcomes of AF versus non-AF patients were compared within each EF quartile. During a median follow-up of 3.35 years, 8,037 patients (45%) died and 7,271 (40%) had at least 1 HFH. Rates of HFH and all-cause mortality increased as EF decreased. The hazard ratios (HRs) of death or HFH for AF versus non-AF patients increased steadily with increasing EF (HR of 1.22, 1.27, 1.45, 1.50 for quartiles 1, 2, 3, and 4, respectively, p = 0.045) driven primarily by the risk of HFH (HR of 1.26, 1.45, 1.59, 1.69 for quartiles 1, 2, 3, and 4, respectively, p = 0.045). In conclusion, in patients with LV dysfunction, the detrimental influence of AF on the risk of HFH is more pronounced in those with more preserved EF. Mitigation strategies for AF with the goal of decreasing HFH may be more impactful in patients with more preserved LV function.

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Methods

This observational study was approved by the institutional review board of the University of Pittsburgh which waived the requirement to obtain consent from patients. We analyzed a cohort of 18,003 consecutive patients with cardiomyopathy (EF ≤50%) who were seen at the hospitals and clinics of the University of Pittsburgh Medical Center between January 1, 2011, and December 31, 2017. From the institutional analytics warehouse, data were collected on each patient, including baseline demographic

Results

Patient baseline characteristics, stratified by EF quartile, are listed in Table 1. It is noted that with increasing EF, the prevalence of HF decreases from 56% in quartile 1 to 33% in quartile 4 (p <0.001). The prevalence of AF, in contrast, was lowest in the lowest EF quartile compared with the other 3 quartiles (p = 0.005). Table 2 lists patient baseline characteristics, stratified by the presence or absence of AF. Patients with AF were older, more likely to be White and men, and had

Discussion

Our data demonstrate that although the risk of the primary end point of HFH and of the secondary end point of death or HFH is higher in patients with more reduced EF, the relative contribution of AF to these end points is strongest in patients with more preserved EF, suggesting that management strategies for AF in patients with more preserved LV function may be most impactful in preventing these adverse outcomes. These results are hypothesis-generating and deserved further investigation.

Declaration of Competing Interest

Dr. Saba has received research support from Abbott and Boston Scientific and reports receiving consultation payments from Boston Scientific and Medtronic. The remaining authors have no conflicts of interest to declare.

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Cited by (1)

Drs. Ayub and Rangavajla contributed equally to this manuscript.

Funding: None.

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