Heart Failure Mortality Rises With Low BMI

It may seem counterintuitive, but people with symptomatic chronic heart failure who are underweight or have a low body mass index (BMI) have a greater risk of death than heavier patients, according to a recently published report.

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A group of investigators examined the influence of BMI on the prognosis of 7,599 people with symptomatic heart failure and varying degrees of left ventricular ejection fraction. During an average follow-up of 37.7 months, 1,831 participants died.

Analysis revealed a graded increase in the risk of death at the lower end of BMI, ranging from 22% higher for BMIs of 25–29.9 to nearly 70% higher for BMIs <22.5. The risk of death was also highest in low BMI and underweight patients who showed no fluid overload.

The authors conclude that there's an association between mortality and low BMI in patients with symptomatic heart failure and either reduced or preserved left ventricular systolic function.

Speculating on possible reasons for this association, the authors note, “Lower BMI in patients with [heart failure]... may have been due to preceding involuntary weight loss or cardiac cachexia, a heightened metabolic or increased catabolic state associated with worse prognosis. By the same token, higher BMI, except when produced by edema, might indicate a greater metabolic reserve, increased tolerance to metabolic stress, and/or a less severe form of [heart failure].”