BACKGROUND/OBJECTIVES: The Sibutramine Cardiovascular OUTcomes (SCOUT) trial showed a significantly increased relative risk of nonfatal cardiovascular events, but not mortality, in overweight and obese subjects receiving long-term sibutramine treatment with diet and exercise. We examined the relationship between early changes (both increases and decreases) in pulse rate, and the impact of these changes on subsequent cardiovascular outcome events in both the placebo and sibutramine groups.

SUBJECTS/METHODS: 9804 males and females, aged ⩾55 years, with a body mass index of 27-45 kg m(-)(2) were included in this current subanalysis of the SCOUT trial. Subjects were required to have a history of cardiovascular disease and/or type 2 diabetes mellitus with at least one cardiovascular risk factor, to assess cardiovascular outcomes. The primary outcome event (POE) was a composite of nonfatal myocardial infarction, nonfatal stroke, resuscitated cardiac arrest or cardiovascular death. Time-to-event analyses of the POE were performed using Cox regression models.

RESULTS: During the initial 6-week sibutramine treatment period, the induced pulse rate increase was related to weight change (1.9±7.7 beats per minute (bpm)  with weight increase; 1.4±7.3 bpm, 0-5 kg weight loss; 0.6±7.4 bpm, ⩾5 kg weight loss). Throughout the subsequent treatment period, those continuing on sibutramine showed a consistently higher mean pulse rate than the placebo group. There was no difference in POE rates with either an increase or decrease in pulse rate over the lead-in period, or during lead-in baseline to 12 months post randomization. There was also no relationship between pulse rate at lead-in baseline and subsequent cardiovascular events in subjects with or without a cardiac arrhythmia.

CONCLUSION: Baseline pulse rate and changes in pulse rate may not be an important modifier nor a clinically useful predictor of outcome in an individual elderly cardiovascular obese subject exposed to weight management.