The significance of nitroglycerin-induced changes in ventricular function after acute myocardial infarction.

The potential of nitroglycerin for improving global and regional ventricular function after acute myocardial infarction and predicting serial change in ventricular function at the time of hospital discharge was investigated. Equilibrium multiple gated blood pool scintigrams were performed at rest before and after sublingual administration of nitroglycerin in 18 patients an average of 36 hours after infarction and again at discharge. Global right and left ventricular function and regional left ventricular function of infarct and noninfarct zones were determined scintigraphically. In the early study nitroglycerin increased both mean (+/- standard deviation) left ventricular ejection fraction (0.51 +/- 0.15 to 0.55 +/- 0.15 ; p less than 0.02) and mean right ventricular ejection fraction (0.42 +/- 0.14 to 0.47 +/- 0.13; p less than 0.05). Left ventricular ejection fraction significantly increased in 5 of the 18 patients. It increased late in five of the six patient who exhibited an increase early after nitroglycerin but in only 2 of the 12 patients who did not exhibit an early increase (p less than 0.06). Regional ejection fraction in the infarct zone increased late in 7 of the 12 patients who exhibited an early increase after nitroglycerin and in none of the 6 who did not exhibit an early increase (p less than 0.05). Both right and left ventricular global ejection fraction and regional ejection fraction showed little late responsiveness to nitroglycerin. Early after infarction, sublingual nitroglycerin improved left, right and regional ejection fraction at the infarct site in some patients. These nitroglycerin-induced changes predicted those patients whose global ventricular function and regional left ventricular function at the infarct site improved late.