Frequency of predischarge ventricular arrhythmias in postmyocardial infarction patients depends on residual left ventricular pump performance and is independent of the occurrence of acute reperfusion. The GISSI-2 Investigators.

OBJECTIVES: To test whether acute reperfusion of the infarct-related vessel after an acute myocardial infarction is associated with a subsequent reduction in spontaneous ventricular arrhythmias that is independent of ventricular ejection fraction, 1,944 patients from the GISSI-2 study population were studied. The patients were selected on the basis of a first myocardial infarction and the availability of two-dimensional echocardiographic ejection fraction and data on the number of premature ventricular contractions per hour on Holter monitoring.

BACKGROUND: It has been suggested that postthrombolytic reperfusion of the culprit vessel may be associated with an increased electrical stability of the infarcted heart, irrespective of its residual pump performance.

METHODS: The predischarge relation between ejection fraction and number of premature ventricular contractions per hour was plotted according to the occurrence (1,309 patients) or not (635 patients) of acute reperfusion, identified noninvasively according to the modifications of the ST segment in serial electrocardiograms obtained in the first 24 h after infarction.

RESULTS: The frequency of premature ventricular contractions increased in a linear fashion with decreasing ejection fraction in both cohorts (p < 0.005 and p < 0.0001); however, there was no significant difference between the slopes and the intercepts of the two regression lines, so that the relation between ejection fraction and number of premature ventricular contractions per hour could be adequately described by a single equation: y (number of premature ventricular contractions) = 33.0-0.42x (ejection fraction) (r = -0.107, p < 0.0001). The results were the same even when differences between group characteristics were accounted for in a multiple regression model.

CONCLUSIONS: It is concluded that 1) the number of premature ventricular contractions per hour after an acute myocardial infarction is dependent in a linear, inverse fashion on the residual ventricular ejection fraction, and 2) this relation is independent of the occurrence of reperfusion in the acute phase of infarction.