THE EFFECTS OF ANTIHYPERTENSIVE DRUGS ON THE AUTONOMIC NERVOUS-SYSTEMIN ELDERLY HYPERTENSIVE PATIENTS WITH SILENT-MYOCARDIAL-ISCHEMIA

To seek further evidence for the participation of sympathetic nervous system in the onset of transient episodes of painless ischemia, we com pared the behavior of the autonomic nervous system by means of power s pectrum analysis of heart rate variability in 15 elderly hypertensive men with angiographically confirmed painless coronary artery disease, and in 10 similar patients without coronary artery disease. An autoreg ressive algorhythm was used to calculate the power spectrum density fr om an electrocardiographic (EGG) recording of 512 consecutive RR inter vals. The power spectrum comprised two main bandwidths: a high-frequen cy band reflecting parasympathetic and a low-frequency band reflecting sympathetic activity. In the hypertensives with painless coronary dis ease sympathetic tone was also assessed alter double-blind placebo-con trolled administration of metoprolol (100 mg/day), amlodipine (10 mg/d ay), quinapril (20 mg/ day), and amlodipine (5 mg/day) plus quinapril (10 mg/day). The hypertensives with painless coronary disease had sign ificantly higher sympathetic activity than those without (low frequenc y: 58.0 +/- 2.0 vs 25.0 +/- 1.0, p < 0.007) but significantly lower pa rasympathetic activity (high frequency: 39.0 +/- 2.0 vs 60.0 +/- 2.0, p < 0.001). Treatment with metoprolol, quinapril and amlodipine plus q uinapril significantly depressed sympathetic activity (p < 0.05).