Tiapamil, a new calcium antagonist: hemodynamic effects in patients with acute myocardial infarction

Abstract

The afterload reduction and myocardial oxygen sparing that results after administration of calcium antagonists suggests a possible role for these drugs in intervention after onset of acute myocardial infarction, but their use in this setting is limited by the possibility that left ventricular failure will develop. Tiapamil is a new verapamil congener. The hemodynamic effects of this drug (1 mg/kg followed by 25 μg/kg/min over 36 hr) were studied in 30 patients randomly assigned in a double-blind manner to a tiapamil or control group within 12 hr of the onset of acute myocardial infarction as diagnosed by Swan-Ganz catherization and gated blood pool scans. Tiapamil reduced heart rate from 83 ± 20 beats/min (mean ± SD) before to 74 ± 19 beats/min after drug (over an average 36 hr), arterial pressure from 128 ± 22/87 ± 14 to 118 ± 16/74 ± 11 mm Hg, rate-pressure product from 10,695 ± 3492 to 8800 ± 2550 units, and systemic vascular resistance from 1732 ± 351 to 1400 ± 350 dynesxsecxcm-5. Tiapamil also increased stroke volume index from 34.7 ± 12.1 to 41.6 ± 12.0 ml/m2, left ventricular ejection fraction from 50.1 ± 14.8% to 56.4 ± 17.4% (at 24 hr), left ventricular end-diastolic volume index from 71.3 ± 23.1 to 80.5 ± 23.7 ml/m2, and peak diastolic filling rate (an index of diastolic relaxation) from 2.1 ± 0.9 to 2.6 ± 0.8 end-diastolic volumes/sec (p