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Atrial Fibrillation in Diastolic Heart Failure
Study Questions:
What is the importance of atrial fibrillation (AF) compared with sinus rhythm (SR) in heart failure (HF) with preserved ejection fraction (HFpEF) versus HF with mid-range EF (HFmrEF) versus HF with reduced EF (HFrEF)?
Methods:
The study authors assessed prevalence of, associations with, and prognostic impact of AF in HFpEF versus HFmrEF versus HFrEF in the SwedeHF (Swedish Heart Failure Registry) registry patients enrolled from 2000 to 2012, enriched with patient-level data from national health care registries. To avoid bias due to data not missing at random, the authors handled missing baseline covariate data by multiple imputation by chained equations. The primary outcome was all-cause mortality, and separate secondary outcomes were composite of all-cause death and HF hospitalization and composite of all-cause death and stroke or transient ischemic attack (TIA). They used Kaplan-Meier method to estimate survival and event-free survival comparing HFpEF, HFmrEF, and HFrEF, and AF and SR. The authors utilized univariable and multivariable Cox regression to estimate the risk of outcomes, separately in HFpEF, HFmrEF, and HFrEF, according to presence of AF, with SR as reference category.
Results:
The study cohort was comprised of 41,446 HF patients, of whom 23% had HFpEF, 22% had HFmrEF, and 55% had HFrEF. The prevalence of AF was 65%, 60%, and 53% in HFpEF, HFmrEF, and HFrEF, respectively. The CHA2DS2-VASc (congestive HF, hypertension, age ≥75 years, diabetes mellitus, prior stroke or TIA or thromboembolism, vascular disease, age 65-74 years, and sex category) score was 4.9 ± 1.55, 4.6 ± 1.64, and 4.3 ± 1.72 in patients with AF and HFpEF, HFmrEF, and HFrEF, respectively. Independent associations with AF were similar in HFpEF, HFmrEF, and HFrEF and included older age, male, duration of HF, prior myocardial infarction, and prior stroke or TIA. The adjusted hazard ratios for AF versus SR in HFpEF, HFmrEF, and HFrEF were the following: for death, 1.11 (95% confidence interval [CI], 1.02-1.21), 1.22 (95% CI, 1.12-1.33), and 1.17 (95% CI, 1.11-1.23); for HF hospitalization or death, 1.17 (95% CI, 1.09-1.26), 1.29 (95% CI, 1.20-1.40), and 1.15 (95% CI, 1.10-1.20); and for stroke or TIA or death, 1.15 (95% CI, 1.07-1.25), 1.23 (95% CI, 1.13-1.34), and 1.19 (95% CI, 1.14-1.26).
Conclusions:
The authors concluded that AF was progressively more common with increasing EF, but was associated with similar clinical characteristics in HFpEF, HFmrEF, and HFrEF. AF was associated with similarly increased risk of mortality, HF hospitalization, and stroke or TIA in all EF groups. In contrast, AF and SR populations were considerably different regarding associated patient characteristics and outcomes.
Perspective:
This is an important study because it demonstrates that AF is more common in diastolic HF. Further studies are now needed to determine whether this finding is due to causes such as sleep apnea or increased left atrial size secondary to hypertension. This study needs to be replicated in the United States to determine whether these findings are applicable to the minority population. Also, as the authors point out, the finding of increased AF in diastolic HF should be kept in mind when designing clinical trials investigating therapies for HFpEF.
Keywords: Arrhythmias, Cardiac, Atrial Fibrillation, Cardiac Surgical Procedures, Cause of Death, Diabetes Mellitus, Disease-Free Survival, Geriatrics, Heart Failure, Heart Failure, Diastolic, Hypertension, Ischemic Attack, Transient, Myocardial Infarction, Secondary Prevention, Sleep Apnea Syndromes, Stroke, Stroke Volume, Thromboembolism
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