Acute haemodynamic effects of diltiazem in patients with recent Q-wave myocardial infarction

The effects of diltiazem on left ventricular systolic and diastolic function were studied in 14 patients with a recent (12-20 days) Q-wave myocardial infarction. Left ventriculography with simultaneous recording of high-fidelity left ventricular pressure was performed in control conditions, and after i.v. administration of diltiazem (0.2 mg kg-1 as a bolus followed by constant infusion of 0.005 mg kg-1 min-1 lasting 8-10 min). After the administration of the drug, left ventricular systolic pressure decreased by 12.7% and mean circumferential wall stress by 14% (both P less than 0.01); the heart rate did not change; the ejection fraction increased by 9.6% (P less than 0.05) and maximum dP/dt/P by 11% (P less than 0.01). Quantitative segmental wall motion analysis showed that the beneficial effects of diltiazem on global left ventricular systolic function were associated with an increase in contraction in hypokinetic regions, where they were supplied by normal or diseased coronary vessels (both P less than 0.01). Left ventricular end-diastolic pressure decreased by 23.6% (P less than 0.05) and minimal diastolic pressure by 38% (P less than 0.05). Passive diastolic properties of the left ventricular chamber remained unaltered but isovolumic relaxation markedly improved: the T constant decreased 26% (P less than 0.01). Thus, in patients with a recent Q-wave myocardial infarction, the i.v. administration of diltiazem unloads the left ventricular chamber without showing depressant effects on myocardial contractility.