Selection of medical treatment in stable angina pectoris: results of the International Multicenter Angina Exercise (IMAGE) Study

OBJECTIVES: The present study was designed to investigate which characteristics of anginal symptoms or exercise test results could predict the favorable anti-ischemic effect of the beta-adrenergic blocking agent metoprolol and the calcium antagonist nifedipine in patients with stable angina pectoris. BACKGROUND: The characteristics of anginal symptoms and the results of exercise testing are considered of great importance for selecting medical treatment in patients with chronic stable angina pectoris. However, little information is available on how this first evaluation may be used to select the best pharmacologic approach in individual patients. METHODS: In this prospective multicenter study, 280 patients with stable angina pectoris were enrolled in 25 European centers. After baseline evaluation, consisting of an exercise test and a questionnaire investigating patients' anginal symptoms, the patients were randomly allocated to double-blind treatment for 6 weeks with either metoprolol (Controlled Release, 200 mg once daily) or nifedipine (Retard, 20 mg twice daily) according to a parallel group design. At the end of this period, exercise tests were repeated 1 to 4 h after drug intake. RESULTS: Both metoprolol and nifedipine prolonged exercise tolerance over baseline levels; the improvement was greater in the patients receiving metoprolol (p < 0.05). Multivariate analysis revealed that low exercise tolerance was the only variable associated with a more favorable effect within each treatment group. Metoprolol was more effective than nifedipine in patients with a lower exercise tolerance or with a higher rate-pressure product at rest and at ischemic threshold. None of the characteristics of anginal symptoms or exercise test results predicted a greater efficacy of nifedipine over metoprolol. CONCLUSIONS: The results of a baseline exercise test, but not the characteristics of anginal symptoms, may offer useful information for selecting medical treatment in stable angina pectoris.