Body mass index in adult congenital heart disease

Abnormal body mass index (BMI) is associated with higher mortality in various cardiovascular cohorts. The prognostic implications of BMI in adults with congenital heart disease (ACHD) are unknown. We aim to assess the distribution of BMI and its association with symptoms and survival in the ACHD population.

We included 3069 ACHD patients (median age 32.6 years) under follow-up at our institution between 2001 and 2015. Patients were classified based on BMI as underweight (<18.5), normal weight (18.5-25), overweight (25-30) or obese (>30), and symptoms, exercise capacity and mortality were assessed.

Overall, 6.2% of patients were underweight, 51.1% had normal weight, 28.2% were overweight and 14.6% were obese. Higher BMI values were associated with lower all-cause and cardiac mortality on univariable Cox analysis, and this effect persisted after adjustment for age, defect complexity, cyanosis and objective exercise capacity. Higher BMI was especially associated with better prognosis in symptomatic ACHD patients (HR 0.94 (95% CI 0.90 to 0.98), p=0.002) and those with complex underlying cardiac defects (HR 0.96 (95% CI 0.91 to 0.997), p=0.048) In patients with a complex cardiac defect who had repeated weight measurements, weight loss was also associated with a worse survival (HR 1.82 (95% CI 1.02 to 3.24), p=0.04).

ACHD patients with a higher BMI had a lower mortality. The association between BMI and mortality was especially pronounced in symptomatic patients with complex underlying cardiac defects, suggesting that cardiac cachexia may play a role. Indeed, weight loss in complex ACHD patients was linked to an even higher mortality.