A multinational prospective cohort study performed by Barak Zafrir et al. and published in the European Heart Journal concluded that worse cardiovascular outcomes of atrial fibrillation (AF) were associated with heart failure with preserved ejection fraction (HFpEF) and heart failure with middle range ejection fraction (HFmrEF) but not associated with heart failure with reduced ejection fraction (HFrEF).
Heart failure used to be categorized into 2 subtypes: HFpEF > 50% and HFrEF < 40%. A new HF category was defined by European Society of Cardiology comprised heart failure with middle range ejection fraction (HFmrEF) and was defined as heart failure with an EF between 40% and 49%. There was heterogeneity in the literature regarding whether there was any prognostic significance of having AF in patients with HFpEF compared to patients with HFrEF, that was addressed by Zaffir et al.
The investigators used the HF Long-Term Registry of the European Society of Cardiology (ESC) which was a multicenter/multi-country database for conducting their study and included patients with chronic heart failure (CHF, outpatients) and acute heart failure (AHF, inpatients), with a total population number of 14 964 patients out of which 8273 were CHF and 6691 were AHF patients. They followed up these patients for a mean duration of 2.2 years.
“HFpEF and AF share some pathophysiological features including structural and functional remodeling of the left heart leading to prolonged isovolumic relaxation, slow filling, and increased diastolic stiffness. The mentioned factors are associated with an increased risk of mitral regurgitation (MR) as well as pulmonary hypertension (PHTN). Also, the loss of atrioventricular synchrony is associated with more left atrium stiffness in HFpEF compared to HFrEF.”- Dr. Barak Zafir, M.D.
The results of the study showed that the long-term hazard ratio of AF for all-cause death was only statistically significant for HFmrEF (1.296). HF hospitalization was significant for HFmrEF and HFpEF with a hazard ratio of 1.430, and 1.487 respectively. The combined end point hazard ratio was calculated following a multivariable adjustment which was 0.957 for HF rEF (which was not statistically significant), 1.302 for HFmrEF, and 1.365 for HFpEF. Additionally, AF was more prevalent in patients with HFpEF(39%), and HFmrEF (29%), than in patients with HFrEF (27%). The increase in AF prevalence on HFpEF was shown to be associated with clinical signs and symptoms of HF as well.
Zafrir et al discussed that HFpEF and AF shared some pathophysiological features including structural and functional remodeling of the left heart leading to a prolonged isovolumic relaxation, slow filling, and increased diastolic stiffness. It was concluded that the mentioned factors were associated with increasing risk of mitral regurgitation (MR) as well as pulmonary hypertension (PHTN). These mentioned factors and also the loss of atrioventricular synchrony were associated with more left atrium stiffness in HFpEF compared to HFrEF.
Investigators explained the association of AF with adverse cardiovascular outcomes between the EF subtypes by the contribution of AF to HF progression when the EF was higher, while in HFrEF the outcomes of the disease were being determined by HF itself. They also emphasized that HFpEF was associated with less response to HF therapy, which itself contributed to the role of AF in worse clinical outcomes of HFpEF.
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