Body mass index and outcomes in ischaemic versus non-ischaemic heart failure across the spectrum of ejection fraction

Aims Obesity is related to better prognosis in heart failure with either reduced (HFrEF; left ventricular ejection fraction (LVEF) <40%) or preserved LVEF (HFpEF; LVEF >= 50%). Whether the obesity paradox exists in patients with heart failure and mid-range LVEF (HFmrEF; LVEF 40-49%) and whether it is independent of heart failure aetiology is unknown. Therefore, we aimed to test the prognostic value of body mass index (BMI) in ischaemic and non-ischaemic heart failure patients across the whole spectrum of LVEF. Methods Consecutive ambulatory heart failure patients were enrolled in two tertiary centres in Italy and Spain and classified as HFrEF, HFmrEF or HFpEF, of either ischaemic or non-ischaemic aetiology. Patients were stratified into underweight (BMI <18.5 kg/m(2)), normal-weight (BMI 18.5-24.9 kg/m(2)), overweight (BMI 25-29.9 kg/m(2)), mild-obese (BMI 30-34.9 kg/m(2)), moderate-obese (BMI 35-39.9 kg/m(2)) and severe-obese (BMI >= 40 kg/m(2)) and followed up for the end-point of five-year all-cause mortality. Results We enrolled 5155 patients (age 70 years (60-77); 71% males; LVEF 35% (27-45); 63% HFrEF, 18% HFmrEF, 19% HFpEF). At multivariable analysis, mild obesity was independently associated with a lower risk of all-cause mortality in HFrEF (hazard ratio, 0.78 (95% confidence interval (CI) 0.64-0.95), p = 0.020), HFmrEF (hazard ratio 0.63 (95% CI 0.41-0.96), p = 0.029), and HFpEF (hazard ratio 0.60 (95% CI 0.42-0.88), p = 0.008). Both overweight and mild-to-moderate obesity were associated with better outcome in non-ischaemic heart failure, but not in ischaemic heart failure. Conclusions Mild obesity is independently associated with better survival in heart failure across the whole spectrum of LVEF. Prognostic benefit of obesity is maintained only in non-ischaemic heart failure.