Transient myocardial ischemia during daily life in rest and exertional angina pectoris and comparison of effectiveness of metoprolol versus nifedipine

Abstract

The clinical characteristics of 65 patients with mixed angina were classified by means of (1) a questionnaire investigating the proportion of symptoms occurring at rest and on effort, (2) an exercise stress test, (3) 24-hour ambulatory Hotter monitoring, and (4) coronary arteriography. According to the questionnaire, the proportion of effort-induced anginal episodes ranged from 1 to 99%. The ischemic threshold during exercise testing ranged from 110 × 10 2 to 350 × 10 2 mm Hg × beats/min. At least 1 episode of ST-segment depression was observed in 29 of the 65 patients during Hotter monitoring. Ischemic episodes during Holter monitoring were more frequent (p < 0.05) in patients reporting ≥50% of anginal attacks on effort, with moderate to severe limitation of exercise capacity and with multivessel coronary artery disease. The effect on ambulatory ischemia of a 6-week treatment with a β blocker (metoprolol CR, 200 mg once daily) or a dihydropyridine calcium antagonist (nifedipine retard 20 mg twice daily) were then compared according to a double-blind, parallel group design. Metoprolol significantly reduced the number and duration of the ischemic episodes during daily life (p < 0.05) irrespective of the patients' clinical characteristics. Nifedipine was ineffective, particularly in patients with angina predominantly on effort and with a moderate to severe reduction in exercise tolerance. It is concluded that in patients with mixed angina, ischemic episodes during daily life are more likely to occur in patients with a clinical presentation suggesting poor coronary reserve. The administration of a β blocker is highly effective in reducing ambulatory ischemia and should be considered as initial antiischemic treatment for mixed angina.