Presence of obesity is associated with lower mortality in elderly patients with implantable cardioverter defibrillator

Abstract

Background: Higher body mass index (BMI) is associated with greater prevalence of cardiovascular risk factors, yet an inverse relationship between obesity and survival after cardiovascular events has been described. It is unclear whether a similar relationship exists for patients with implantable cardioverter defibrillators (ICDs) at high risk for mortality. We aimed to assess the impact of BMI on mortality and cardiovascular hospitalization in patients with ICD.

Methods: Patients who underwent ICD implantation in 2010-2011 were divided into normal (<25 kg m^-2), overweight (25-29.9 kg m^-2) and obese (⩾30 kg m^-2) groups based on BMI. Clinical parameters were compared and long-term outcomes were determined using χ² test, Wilcoxon's rank-sum test, logistic regression models and Kaplan-Meier curves.

Results: Of 904 patients (mean age 67±13 years), 26% had normal BMI, 32% were overweight and 42% were obese. No significant baseline differences in ventricular ejection fraction, ICD for primary or secondary prevention, history of heart failure, syncope or cardiac arrest existed. Despite a greater prevalence of diabetes, hypertension and prior myocardial infarction, the obese and overweight groups had lower mortality (10.1% and 7.9%, respectively) than the normal group (22.9%, P<0.001). On multivariate logistic regression, BMI in the obese and overweight range (odds ratio (OR): 0.35; 95% confidence interval (CI): 0.21-0.58 and OR: 0.25; 95% CI: 0.13-0.40, respectively) was protective against mortality, whereas history of diabetes (OR: 2.01; 95% CI: 1.30-3.09), myocardial infarction (OR: 1.76; 95% CI: 1.11-2.80), heart failure (OR: 3.88; 95% CI: 1.56-9.66), stroke (OR: 3.19; 95% CI: 1.63-6.23) and history of cardiac arrest (OR: 2.65; 95% CI: 1.37-5.15) were independent risk factors for higher mortality.

Conclusions: A paradoxical relationship between BMI and mortality risk is present in elderly patients with ICD at high risk of sudden death with a lower mortality in obese or overweight patients than in those with normal BMI.