Development and prognosis of non-Q-wave myocardial infarction in the thrombolytic era

Background Data on non-Q myocardial infarctions (MI) are derived primarily from prethrombolytic era studies. Previous trials demonstrated different development rates and none reported on clinical outcomes. Methods Our goal was to determine the incidence and prognosis of non-Q-wave MI among patients with ST-segment elevation receiving thrombolysis. A retrospective analysis of 5 randomized controlled trials was made. The main outcome measures included rates of (1) transformation of ST-segment elevation to Q- and non-Q-wave MI and (2) inhospital and 1-year mortality and reinfarction among patients who subsequently develop a Q or non-Q MI postthrombolysis as compared to controls. Results Non-Q wave development was greater among patients receiving thrombolysis versus placebo/control (3.1% absolute difference, 95% CI 1.2%-5.0%). Among patients receiving thrombolysis, those who developed a non-Q MI experienced significantly lower inhospital and 1-year mortality (absolute differences -3.8% [95% CI -5.2% to -2.4%] and -6.4% [95% CI -9.9% to -3.0%], respectively) and reinfarction (absolute differences -2.9% [95% CI -4.3% to -1.6%] and -3.5% [95% CI -6.1% to -0.9%], respectively) rates, compared with those who evolved a Q MI. Inhospital and 1-year mortality was also significantly lower when compared to placebo/control patients who developed a non-Q MI (absolute differences 4.6% [95% CI -8.2% to -1.1%] and -7.5% [95% CI -12.5% to -2.5%], respectively). Conclusions Patients receiving thrombolysis more often develop a non-Q-wave MI and have a better prognosis than either those who develop a Q MI postthrombolysis or a non-Q MI after standard medical therapy.