Prostacyclin infusion in patients with acute myocardial infarction

To investigate whether prostacyclin protects ischaemic myocardium in humans the effect of prostacyclin or placebo was studied in two groups of patients with acute myocardial infarction who presented within six and 16 hours of the onset of symptoms. Intravenous infusion of prostacyclin or placebo was started immediately after admission at a rate corresponding to 4-5 ng/kg/minute. The infusion was maintained for 72 hours. Clinical status, electrocardiograms, plasma enzyme activity, infarct extension during the infusion, and reinfarction after the infusion were studied. Prostacyclin was well tolerated by most patients: neither systemic blood pressure nor heart rate differed between the two groups. In the 11 patients who received treatment within six hours of the onset of symptoms prostacyclin significantly lowered the maximum plasma activities of creatine kinase MB and lactate dehydrogenase. In the 19 patients who received treatment 6-16 hours after the onset of symptoms prostacyclin had no such effect. None of the patients receiving prostacyclin had an extension of the infarction during the infusion, whereas four patients receiving placebo did; this difference was significant. These data are the first to provide evidence that prostacyclin might limit myocardial injury in patients with acute myocardial infarction.