Improvement in left ventricular function after rapid weight loss in obesity

The effect of rapid weight reduction on left ventricular function and blood pressure was studied in 34 obese subjects, who all weighed more than 30% above their ideal body weight. Subjects with co-existing hypertension (N = 15) and proven coronary artery disease ( N = 9) were included to assess contributions from these factors. Blood pressure (BP) was measured both indirectly and by direct ambulatory intra-arterial methods. Radionuclide ventriculography was performed at rest and at exercise, before and after dieting, which was supervized in hospital (daily intake 330 kCal day−1for 4 weeks). Dieting induced a weight loss of (mean ±SD) 9.6 ±3.5 kg (P<0.0001) in the whole group. The mean daytime intra-arterial blood pressure fell from 157±23/90±15 to 144±21/85±13 mmHg (P<0.0001). The fall in ambulatory intra-arterial diastolic blood pressure did not reach significance in the normotensive and ischaemic groups. The mean resting left ventricular eject ion fraction (LVEF) in the whole group showed a significant reduction after weight loss from 61 ± 10% to 56±6% (P< 0.005). Although the individual groups showed a fall in LVEF, the effect was most marked in the hypertensive group, from 65±9% to 57±5% (P<0.002). Before dieting none of the groups achieved a ‘normal’ 5% rise in LVEF above basal in response to exercise, the hypertensive and the ischaemic groups both showing non-significant falls. This phenomenon was, however, reversed after weight loss. Exercise LVEF improved in all three groups, but remained abnormal in the ischaemic group. Although, diastolic function was abnormal in all three groups, this was most apparent in the hypertensive and ischaemic groups. Weight reduction did not produce any improvements in diastolic function in any of the groups. These data suggest the presence of reversible subclinical left ventricular systolic dysfunction associated with obesity, due to a high cardiac output state and lack of cardiac reserve. Coincident hypertension may indicate those at greater risk, and although the presence of ischaemic heart disease did not influence the pre-diet findings, some dysfunction persisted after weight loss. Diastolic dysfunction was not influenced by rapid weight loss and may reflect structural or metabolic cardiac changes, requiring more time to change.