Effect of short-term infusion of sodium nitroprusside on mortality rate in acute myocardial infarction complicated by left ventricular failure: results of a Veterans Administration cooperative study.

Eight hundred twelve men with presumed acute myocardial infarction and left ventricular filling pressure of at least 12 mm Hg participated in a randomized double-blind placebo-controlled trial to assess the efficacy of a 48-hour infusion of sodium nitroprusside. The mortality rates at 21 days (10.4 per cent in the placebo group and 11.5 per cent in the nitroprusside group) and at 13 weeks (19.0 per cent and 17.0 per cent, respectively) were not significantly affected by treatment. The efficacy of nitroprusside was related to the time of treatment: the drug had a deleterious effect in patients whose infusions were started within nine hours of the onset of pain (mortality at 13 weeks, 24.2 per cent vs. 12.7 per cent; P = 0.025) and a beneficial effect in those whose infusions were begun later (mortality at 13 weeks, 14.4 per cent vs. 22.3 per cent; P = 0.04). Nitroprusside should probably not be used routinely in patients with high left ventricular filling pressures after acute myocardial infarction. However, the results in the patients given late treatment suggest that those with persistent pump failure might receive sustained benefit from short-term nitroprusside therapy.