Objective: To investigate the combined effect of obesity and physical capacity, measured by body mass index (BMI) and six-minute walk distance (SMWD) test respectively, on the prognosis of patients with systolic heart failure (SHF).
Background: Obesity paradox is consistently demonstrated in cohorts of SHF patients. Recent reports suggest that cardiorespiratory fitness modifies the relationship between adiposity measures and mortality.
Patients and Methods: We studied 543 consecutive advanced SHF patients, at their initial visit to the HF clinic. SMWD was categorized as low (<300meter) or high (≥300meter) physical capacity, and BMI according to standard classification. Association of the BMI*SMWD product (kg/meter) with total mortality was assessed by Cox proportional-hazards analyses.
Results: There were 216 deaths during a mean follow-up of 40 months. Obesity paradox was observed in the study cohort, but was attenuated in the high physical capacity group. High compared to low physical capacity was associated with significant survival benefit in both the normal-weight and obese patients subgroups (Log-rank p=0.003 and p=0.009, respectively). A progressive inverse relationship between quartiles of BMI*SMWD product and mortality risk was observed. Compared with the lower quartile (Q1, reference group), Q2 had hazard-ratio (HR) of 0.70 (95% C.I 0.49-0.98), Q3 HR 0.60 (0.41-0.87) and Q4, HR 0.39 (0.24-0.63).
Conclusions: Obesity paradox exists in SHF patients but is modified by the degree of physical capacity. Therefore, the combined parameter of BMI*SMWD product is more reliable in predicting long term mortality risk prediction in SHF patients.
