Impact of Mean Corpuscular Volume on Prognosis in Patients With Acute Decompensated Heart Failure With Preserved Ejection Fraction ― Insights From the PURSUIT-HFpEF Registry ―

Background: The prognostic significance of mean corpuscular volume (MCV) in patients with heart failure with preserved ejection fraction (HFpEF) remains unclear. Methods and Results: This post hoc analysis included 1,206 patients with HFpEF from the PURSUIT-HFpEF (Prospective Multicenter Observational Study of Patients with Heart Failure with Preserved Ejection Fraction) Registry. Patients were stratified into tertiles according to MCV at discharge: ≤90.1 fL (low; n=405); >90.1–≤95.1 fL (middle; n=408); and >95.1 fL (high; n=393). The primary endpoint was a composite of all-cause mortality and heart failure (HF) readmission. Secondary endpoints were cardiac death, non-cardiac death, and HF readmission. Restricted cubic spline analyses and multivariable Cox proportional hazards models were used to evaluate the associations between MCV and clinical outcomes, whereas Fine–Gray models were applied for HF readmission. During a median follow up of 2.4 (range 0.8–4.1) years, the primary endpoint occurred in 719 patients. Elevated MCV values were independently associated with an increased risk of the primary endpoint. Compared with the middle-MCV group, the high-MCV group had a significantly higher risk of the primary endpoint (adjusted hazard ratio 1.21; 95% confidence interval 1.01–1.45; P=0.044). Elevated MCV was also associated with increased risks of cardiac and non-cardiac death, whereas no significant association was observed with HF readmission after adjustment. Conclusions: In HFpEF, elevated MCV was independently associated with adverse clinical outcomes, particularly mortality, and may serve as a readily available biomarker for risk stratification.