RELATIONSHIP BETWEEN CALCIUM-CHANNEL ANTAGONISTS AND NOCTURNAL HYPOTENSION AND AUTONOMIC IMBALANCE IN PATIENTS WITH A PREVIOUS MYOCARDIAL-INFARCTION

The present study was conducted to evaluate the effect of calcium chan nel antagonists on diurnal changes in blood pressure and on autonomic function in 71 patients who were receiving a calcium channel antagonis t because they had previously suffered a myocardial infarction. Ambula tory blood pressures and Holter ECGs were recorded simultaneously for 24 h. Autonomic function was assessed by heart rate variability. Noctu rnal systolic pressure was greater than or equal to 90 mmHg in 63 pati ents (group I) and < 90 mmHg in 8 patients (group II). Significant day to night changes in high-frequency power (from 4.3+/-1.2 to 4.5+/-1.0 /m(2)) as well as in the ratio of low-frequency power to high-frequenc y power (from 1.3+/-0.1 to 1.1+/-0.2) were observed in group I, wherea s such changes were blunted in group II. When the calcium antagonist w as discontinued or the dose was reduced in group II, the autonomic imb alance improved along with elevation of nocturnal systolic blood press ure. Thus, nocturnal blood pressure should be monitored when such drug s are administered for the treatment of ischemic heart disease to a pa tient with a previous myocardial infarction. If nocturnal hypotension occurs, the dose should be reduced or the drug should be discontinued.