Pulmonary ventilation in long-term beta-adrenergic blockade after myocardial infarction

In a double-blind, randomized study, the long-term effects of timolol and placebo on FEV1, PEFR, FVC, VC, respiratory rate and heart rate were compared in 32 patients surviving acute myocardial infarction, 17 on timolol and 15 on placebo. The patients were assessed before and after 1, 3 and 6 months of medication, and then every 6 months for up to 2 years; the mean observation period was 17.4 months. Timolol decreased FEV1 significantly (9-17%) throughout the study. PEFR and FVC fell by 4-13% and 9-11%, respectively, on timolol; the reductions were significant at 3, 6 and 24 months, and at 1, 3 and 6 months, respectively. VC showed only small changes and respiratory rate did not change. In only one patient were the changes in pulmonary function of clinical relevance. Thus, significant, persisting airways dysfunction was induced by long-term beta-adrenergic blockade in patients surviving myocardial infarction.