Prevalence and Prognostic Implication of Atrial Fibrillation in Heart Failure Subtypes: Systematic Review and Meta-Analysis

Background Atrial fibrillation (AF) and heart failure (HF) portends a poor outcome. The HF universal definition has incorporated Heart Failure with mildly reduced Ejection Fraction (HFmrEF). We sought to evaluate the relationship between AF and different HF subtypes, with emphasis on HFmrEF.Methods PubMed and Embase databases were searched up to July 2022. Studies that classified HF with EF>50% as Heart Failure with Preserved Ejection Fraction (HFpEF); EF 40%-49% as HFmrEF; and EF ,40% as Heart Failure with Reduced Ejection Fraction (HFrEF) were included.Results Fifty (50) eligible studies, with 126,720 acute HF and 109,683 chronic HF patients, were included. Ten percent (10%) and 12% of patients constituted HFmrEF subtype in patients with acute and chronic HF, respectively. The AF prevalence was 38% (95%CI [33, 44], I-2=96.9%) in HFmrEF, as compared to 43% (95% CI [39, 47], I-2=97.9%) in HFpEF, and 32% (95%CI [29, 35], I-2=98.6%) in HFrEF in acute HF patients. Meta -regression showed HFmrEF shared age as a determinant for AF prevalence with HFrEF and HFpEF. Similar AF prevalence also was observed in chronic HF. Compared to sinus rhythm, AF was associated with an increased risk of all-cause mortality in all HF subtypes: HFmrEF (n=6; HR 1.28, 95%CI [1.08, 1.51], I-2=71%), HFpEF (n=10; HR 1.14, 95%CI [1.06, 1.23], I-2=55%) and HFrEF (n=9; HR 1.11, 95%CI [1.02, 1.21], I-2=78%).Conclusion The prevalence of AF was intermediate for HFmrEF in between HFpEF and HFrEF, with determinants shared with either HF subtype. The co-existence of AF and HF predicts an increased all-cause mortality across all categories of HF.