Left ventricular function before and after diltiazem in patients with coronary artery disease

Left ventricular contraction, relaxation and diastolic mechanics were investigated before and after intravenous administration of 15 mg of diltiazem in 15 patients with coronary artery disease. High fidelity left ventricular pressure measurements were performed in all 15 patients, with simultaneous biplane cineangiography in 13. The time constant of left ventricular isovolumic pressure decay was calculated from the linear relation of left ventricular pressure and its rate of change with time (negative dP/dt). Frame by frame volume analysis through one cardiac cycle was completed to construct volume-time and pressure-volume curves before and after the administration of diltiazem.After diltiazem, left ventricular peak systolic pressure decreased from 124 to 113 mm Hg (p < 0.001), while left ventricular end-diastolic pressure and heart rate were not altered. Maximal positive dP/dt also remained unchanged. End-diastolic volume was not changed after diltiazem, but end-systolic volume increased from 48 to 52 ml/m2(p < 0.025); as a result, ejection fraction decreased slightly from 57 to 55% (p < 0.025). The time constant of left ventricular pressure decay and maximal negative dP/dt decreased from 58 to 54 ms (p < 0.025) and from −1,404 to −1,321 mm Hg/s (p < 0.025), respectively. Peak early diastolic filling rate increased from 621 to 752 ml/s (p < 0.01) in association with an increase in filling volume during the first half of diastole from 60 to 68% (p < 0.005). No consistent displacement of the diastolic pressure-volume curve was observed after diltiazem.This study indicates that diltiazem reduces afterload and depresses myocardial contractility in patients with coronary artery disease. In contrast, it improves left ventricular relaxation, which may contribute in part to the enhancement of early diastolic filling. However, left ventricular passive diastolic properties remain uninfluenced