Cardiac Structure and Function and Insulin Resistance in Morbidly Obese Patients: Does Superobesity Play an Additional Role?

Objective: To evaluate the impact of superobesity, defined as body mass index (BMI) ≥50, on cardiac structure and function. Methods: Using echocardiography, we studied 198 asymptomatic patients (mean age 48 ± 13 years, 29.3% were men) with a BMI ≥40. Insulin resistance was measured using the Homeostasis Model Assessment of insulin resistance (HOMA-IR). Patients were divided into 2 groups: morbidly obese (BMI ≥40 and <50; n = 160) and superobese (BMI ≥50; n = 38). Results: There were no significant differences in age, gender, hypertension and diabetes between groups. Superobese patients had higher LV mass (66.0 ± 14.7 vs. 59.9 ± 11.9 g/m2.7, p = 0.007), left ventricular (LV) end-diastolic (33.8 ± 7.7 vs. 31.5 ± 7.1 ml/m2.7, p = 0.041) and end-systolic (12.2 ± 3.6 vs. 10.9 ± 2.8 ml/m2.7, p = 0.016) volumes, left atrial volume (13.8 ± 4.5 vs. 12.2 ± 3.9 ml/m2.7, p = 0.029), peak velocity of transmitral flow in early diastole/early diastolic peak myocardial velocity ratio (9.1 ± 2.6 vs. 8.2 ± 2.2, p = 0.03) and HOMA-IR (9.7 ± 7.3 vs. 7.3 ± 6.5, p = 0.047). LV ejection fraction was similar. Conclusions: Superobesity is associated with insulin resistance and a worse impact on cardiac remodeling and LV diastolic function than morbid obesity. Prospective studies are needed to evaluate whether such further classification of morbid obesity could stratify the cardiovascular risk in these patients more accurately.