Cardiac mechanics and function in obese normotensive persons with normal coronary arteries.

Obesity is associated with several cardiac abnormalities, but its effects on cardiac loading conditions and contractile function are controversial. The frequent coexistence of obesity with systemic hypertension and coronary artery disease further complicates evaluation of cardiac function in obese persons. Therefore, cardiac mechanics and contractile function were examined at cardiac catheterization in 14 obese persons (50 +/- 5% overweight) who were free of systemic hypertension and angiographic coronary narrowing. Twelve lean subjects who underwent catheterization for chest pain, found to be free of cardiac abnormalities, served as control subjects. Preload, estimated as end-diastolic stress, was greater in obese persons (48 +/- 5 kdynes/cm2) than in lean persons (32 +/- 3 kdynes/cm2) (p less than 0.01). Afterload, estimated by end-systolic stress, was also greater in obese persons: 124 +/- 15 kdynes/cm2 vs 95 +/- 6 kdynes/cm2 (p less than 0.05). Ejection fraction was similar in obese (0.69 +/- 0.02) and lean persons (0.71 +/- 0.02). Mean velocity of circumferential fiber shortening and the ratio of end-systolic stress to end-systolic volume index were also similar in both groups. The value for stress velocity of fiber shortening relation fell within the range of the normal subjects in all but 1 obese subject. Thus, although abnormalities in loading conditions are present in normotensive persons who are moderately obese, contractile function is usually normal.