AFib’s impact on heart failure outcomes varies by subtype
Higher ejection fractions (EFs) among heart failure patients are associated with an increased incidence of atrial fibrillation (AF) and worse cardiovascular outcomes, according to data from a multinational European registry.
Barak Zafrir, MD, and colleagues studied nearly 15,000 patients from the European Society of Cardiology Heart Failure Long-Term Registry. Twenty-six percent of the patients had heart failure with preserved EF (HFpEF; EF of 50 percent or higher), while 21 percent had HF with midrange EF (HFmrEF; EF between 40 and 50 percent) and 53 percent had HF with reduced EF (HFrEF; EF below 40 percent).
The prevalence of AF was 27 percent for HFrEF, 29 percent for HFmrEF and 39 percent in HFpEF patients. When outcomes were adjusted for multiple variables and stratified by ejection fraction subtypes, the researchers found atrial fibrillation was associated with:
- A 3.6 percent increased risk of heart failure hospitalizations and a 4 percent decreased risk of a combination of HF hospitalization and all-cause mortality for HFrEF at one year—both statistically insignificant findings.
- A 43 percent increased risk of HF hospitalization for HFmrEF, along with a 30 percent increased risk of HF hospitalization or death.
- A 49 percent increased risk of HF hospitalization for HFpEF, plus a 37 percent increased risk of death or HF hospitalization.
“The independent association of AF with either HF hospitalizations by itself or combined with mortality remained significant only in patients with HFpEF and HFmrEF,” Zafrir and colleagues wrote in the European Heart Journal. “In contrast to the ‘common belief,’ AF in HFrEF was not related to worse outcomes compared to (sinus rhythm) either in chronic presentation or in acute decompensation of these patients.”
The authors said it is becoming increasingly important to understand how the commonly coexisting conditions of HF and AF interact and affect prognoses, given that both are growing in prevalence as the population ages. Also, they noted HFmrEF still represents a gray area of research because it includes a range of EF that has traditionally been excluded from HFrEF clinical trials and is only sporadically included in HFpEF trials.
Causation couldn’t be proved from this registry analysis, but Zafrir et al. ventured an explanation for the stronger association between AF and adverse outcomes at higher ejection fractions.
“With higher EF, AF may contribute to progression of HF and worsen outcomes, whereas with lower EF, the HF disease itself and its severity determines the outcomes, and not primarily AF, which may be more of a bystander,” they wrote. “The particularly greater role of AF in HFpEF may also be related to the lesser response to HF therapy.”
The researchers noted patients across all subtypes who had AF tended to be older, have reduced functional capacity, higher heart rates and more previous HF hospitalizations. Participants in the study were 66 years old on average and 67 percent male.
Daniel joined TriMed’s Chicago editorial team in 2017 as a Cardiovascular Business writer. He previously worked as a writer for daily newspapers in North Dakota and Indiana.