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/m2), normal-weight (BMI 18.5-24.9 kg/m2), overweight (BMI 25-29.9 kg/m2), mild-obese (BMI 30-34.9 kg/m2), moderate-obese (BMI 35-39.9 kg/m2) and severe-obese (BMI ≥40 kg/m2) 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.