Acute Hemodynamic Effects of Amlodipine 15 Days After a Myocardial Infarction in Normotensive Patients Treated with Atenolol

The acute hemodynamic effects of 20 mg iv amlodipine were evaluated in a placebo-controlled study in 16 normotensive patients 15 ± 1 days after an acute myocardial infarction by covariance analysis. Atenolol was given orally for at least 1 week before the study to maintain the heart rate between 50 and 60 beats/min. All patients were given two doses of 10 mg of amlodipine, or 10 ml of a placebo twice, in iv infusion lasting 2 minutes each. Hemodynamic data were collected during the control period and 15 minutes after each of the two amlodipine or placebo infusions. At the time of the last measurements, 15 minutes after the second amlodipine or placebo infusion, the plasma amlodipine level was 31 ± 16 μg/l and the plasma atenolol level was 773 ± 564 μ/l in the amlodipine group versus 795 ± 916 μg/l in the placebo group. There were no chronotropic, dromotropic, or inotropic effects. The main hemodynamic effect was a fall in systemic vascular resistance (1548 ± 591 dynes.sec.cm-5to 1176 ± 526 dynes.sec.cm-5, p = 0.045) with decreases in aortic pressure and in the left ventricular stroke work index. The left ventricular ejection fraction was 51 ± 12% in the placebo group and 56 ± 15% in the amlodipine group (ns) during the control period, and did not change after infusion of placebo or amlodipine. Left ventricular compliance seemed to be enhanced by amlodipine, because the end-diastolic left ventricular volume index rose from 82 ± 11 ml/m2 to 87 ± 11 ml/m2 (p = 0.026) 15 minutes after the beginning of the second infusion of 10 mg of amlodipine, without any change in end-diastolic left ventricular pressure. Intravenous infusion of 20 mg of amlodipine is well tolerated 15 days after acute myocardial infarction in normotensive patients without deeply depressed left ventricular systolic function and chronically treated with atenolol. The main hemodynamic effects observed are potentially useful for such patients.