In comparison with conservative management (medical treatment without reperfusion therapy), fibrinolytic therapy leads to improved left ventricular systolic function and survival in patients with myocardial infarction associated with either ST-segment elevation or left bundle-branch block. In a pooled analysis of nine large trials, the rate of death at 35 days was 9.6% among patients receiving fibrinolytic therapy, as compared with 11.5% among control subjects.
However, fibrinolytic therapy has several limitations. First, among those presenting with myocardial infarction with ST-segment elevation, some patients (27% in one report) have a contraindication to fibrinolysis. Second, in approximately 15% of patients given fibrinolytic therapy, thrombolysis does not occur. Third, about a quarter of those receiving fibrinolytic therapy have reocclusion of the infarct-related artery within 3 months after the myocardial infarction, with a resultant reinfarction. These limitations are minimized with the use of primary PCI.
In a meta-analysis of 23 randomized, controlled comparisons of primary PCI (involving 3872 patients) and fibrinolytic therapy (3867 patients), the rate of death at 4 to 6 weeks after treatment was significantly lower among those who underwent primary PCI (7% vs. 9%). Rates of nonfatal re-infarction and stroke were also significantly reduced. Most of these trials were performed in high-volume interventional centers by experienced operators with minimal delay after the patient’s arrival. If primary PCI is performed at low-volume venues by less-experienced operators with longer delays between arrival and treatment, such superior outcomes may not be seen.