The myth of QT shortening by weight loss and physical training in obese subjects with coronary heart disease.

This study aims to describe the changes that a period of low-calorie diet and physical training determines in heart rate and in corrected QT (QTc) interval in obese patients with coronary heart disease (CHD) and to verify whether it is effective in shortening the QT interval using three different methods for QT correction. Two hundred and seventy obese white patients (162 males--60%) affected with stable CHD and treated with ß-blockers were retrospectively studied in the setting of a program aimed at losing weight through training (aerobic activity + strength exercise) and diet (80% of estimated resting energy expenditure). Age was related to RR interval, QTc was related to left ventricular ejection fraction (EF) while sex exerted no effects. At the end of the study period heart rate decreased by 8.3% and noncorrected QT increased by 3.0%; QT corrected with the Bazett formula decreased by 0.7% (P = 0.007), QT corrected with the Fridericia formula increased by 0.5% (P = 0.023), whereas the modifications were nonsignificant when the Framingham correction was used. In conclusion, contrary to the current views, physical training and diet, which are effective in reducing heart rate, produced no clinically relevant change in the QT interval.

What are we measuring? Considerations on subjective ratings of perceived exertion in obese patients for exercise prescription in cardiac rehabilitation programs.

We sought to describe the differences in exercise prescription in obese subjects using attained METs as compared to the subjective perception of the effort using the Borg scale ratings of perceived exertion (Borg RPE). We studied 552 obese patients who underwent an exercise stress test in the setting of a rehabilitation program. Exercise was prescribed at 70% of peak attained METS. This method was compared to an exercise level prescription that induces a subjective perception of mild fatigue (13 on the 20 points Borg scale). Attained METS were 6.2+/-2.5 and Borg RPE was 15.2+/-1.7. Borg RPE was negatively related to intensity and duration of exercise. Females, patient with a lower level of education and patients on diuretics perceived higher efforts. Patients who stopped exercising because of dyspnea or angina reached a lower level of METs (4.7+/-1.7 vs 6.3+/-2.7 METs; P<0.001) but the perceived effort was similar (15.5+/-1.7 vs 15.2+/-1.7; P=0.252). The subjective method would have yielded a significantly higher training workload: 5.4+/-2.3 vs 4.3+/-1.8 (P<0.001). In conclusion, in obese patients, Borg RPE is not equivalent to attained METs in exercise prescription and it influenced by educational level.

Short-term effects of a hypocaloric diet and a physical activity programme on weight loss and exercise capacity in obese subjects with chronic ischaemic heart disease: a study in everyday practice.

OBJECTIVE: The objective of this paper is to describe the effects of a rehabilitation programme in obese patients affected with chronic ischaemic heart disease; to identify the factors that influence weight loss and improvement in exercise capacity in everyday practice. METHODS AND RESULTS: We studied 562 white patients (381 men) who followed a 23.3 +/- 3.9 days in-hospital programme. They attended daily sessions of aerobic activity (cycloergometer, walking, and strength exercise); a low-calorie diet was set at approximately 80% of resting energy expenditure. By the end of the programme BMI decreased from 38.0 +/- 4.9 to 36.7 +/- 4.8 kg/m2 (P < 0.001 ). Attained metabolic equivalents (METs) increased from 6.2 +/- 2.5 METs to 7.3 +/- 2.7 (P < 0.001). Age, sex, presence of diabetes and education level were significantly related to the outcomes. Patients who took beta-blockers and statins had less BMI improvement: -1.2 +/- 0.7 kg/m2 vs. -1.4 +/- 0.6 (P = 0.013) and -1.3 +/- 0.6 vs. -1.4 +/- 0.7 (P = 0.023), respectively. Patients that took diuretics and angiotensin receptor blockers (ARB) had less improvement in exercise capacity: 0.9 +/- 1.0 METS vs. 1.3 +/- 1.3 (P < 0.001) and 0.8 +/- 1.3 vs. 1.2 +/- 1.3 (P = 0.011 ), respectively. After a median interval of 358 days, 152 patients were seen at a follow-up visit: their BMI increased by 1.0 +/- 2.4 kg/m2 and only 21% of patients lost weight. CONCLUSIONS: Rehabilitation improves exercise capacity and induces significant weight loss in obese patients with stable IHD, but women, diabetic, elderly and poorly educated subjects obtained unsatisfactory results. Use of diuretics and ARB seem to worsen the results. At follow-up only a small percentage of patients further improves BMI.