LEFT-VENTRICULAR SYSTOLIC AND DIASTOLIC FUNCTION IN SEVERE OBESITY - A RADIONUCLIDE STUDY

To verify the impact of severe obesity (defined as body mass index > 3 1 kg/m(2)) on left ventricular (LV) function, 32 asymptomatic obese bu t otherwise healthy subjects (16 men; age 38 +/- 11 years) voluntarily underwent first-pass and equilibrium Tc-99m radionuclide angiography at rest and, in 22 of them, during bicycle supine exercise. Data were compared to those obtained from 10 normal volunteers (age 48 +/- 13; p < 0.05, vs. obeses). End-diastolic and stroke volumes did not differ between the two groups, whereas end-systolic volume was significantly higher in obese subjects (67 +/- 20 vs. 49 +/- 20 ml; p < 0.05), and, as a consequence, LV ejection fraction at rest was decreased in obese subjects (59 +/- 7%) compared to normals(65 +/- 6%; p < 0.05). Due to the higher heart rate in obese subjects (81 +/- 13 vs. 69 +/- 10 bpm, respectively; p < 0.05) cardiac output was significantly greater compa red to normals (7.1 +/- 0.8 vs. 6.2 +/- 0.2 liters/min, respectively; p < 0.01). During exercise, ejection fraction normally increased in no rmals (70 +/- 7%; p < 0.001, vs. baseline) but not in obese subjects ( 60 +/- 9%; p = nonsignificant vs. baseline). In addition, systolic blo od pressure/end-systolic volume ratio was significantly decreased in o bese subjects (2.3 +/- 1.3) compared to normals (2.8 +/- 1.6; p < 0.05 ). Peak filling rate, normalized to end-diastolic counts per second, w as significantly lower in obese subjects (2.2 +/- 1.3) compared to nor mals (2.8 +/- 1.6; p < 0.05). This difference was also true when peak filling rate was computed in stroke counts per second (3.8 +/- 0.8 in obeses vs. 4.4 +/- 0.4 in normals; p < 0.05). Repeat analysis in a sub group of 10 young obese subjects (age 130 years) confirmed decreased e jection fraction at rest (60 + 4%; p < 0.05) and peak filling rate (2. 4 +/- 0.4 end-diastolic counts/s; p < 0.05), as well as the lack of ej ection fraction increase during exercise (59 +/- 9%). Thus, these data indicate a subclinical impairment of LV systolic and diastolic functi on at rest and during exercise in asymptomatic severely obese but othe rwise healthy subjects.