Effects of streptokinase during acute myocardial infarction on the signal-averaged electrocardiogram and on the frequency of late arrhythmias

Abstract

Although a number of studies have shown that the incidence of late potentials is lower after thrombolytic therapy, it is not known whether this is paralleled by fewer arrhythmic events during long-term follow-up. In patients with first acute myocardial infarction, filtered QRS duration was significantly shorter when treated with streptokinase (95 ± 11 ms, n = 53) than when treated with conventional therapy (99 ± 12 ms, n = 77, p < 0.05). The low-amplitude signal (D 40) was shorter after thrombolysis (28 ± 11 vs 33 ± 12 ms, p < 0.02). Terminal root-mean-square voltage did not differ significantly (41 ± 24 vs 35 ± 23 μV). Irrespective of treatment, late potentials were predictive in the complete group (n = 171) for arrhythmic events during follow-up (13 ± 6 months, range 6 to 24) (hazard ratio 7.7, p < 0.02, Cox proportional-hazards survival analysis), but treatment (streptokinase vs conventional) did not significantly affect outcome when added to the model. It is concluded that thrombolysis prevents the development of late potentials. However, this study does not confirm the hypothesis that prevention of late potentials leads to a decrease in arrhythmic events.