Diltiazem reduced infarct size but not ventricular arrhythmias in 48 hour coronary embolized dogs

The calcium antagonist, diltiazem, was examined for its ability to limit infarct size and to diminish the severity and frequency of the ventricular arrhythmias in closed chest dogs following coronary occlusion. Diltiazem was administered 100 micrograms/kg as a bolus, followed by 15 micrograms/kg/min infusion for 48 h, starting 10 min after coronary occlusion (11 dogs). The control groups (9 dogs) received an equal volume of saline. Risk area and regional myocardial blood flow was measured with radioactive microspheres 5 min after coronary embolization. Forty-eight hours after embolization, the dogs were sacrificed, the hearts sectioned into 4 mm slices and the slices were stained with triphenyl tetrazolium chloride to measure the infarct size. Risk size was determined by autoradiography of the microspheres. Infarct size, expressed as a percentage of the area at risk, was significantly lower in the diltiazem treated group than in the control group (47.4 +/- 8.9 vs. 76.1 +/- 6.4%). However, the severity and frequency of the ventricular arrhythmias for the first 24 h was not any different between two groups.