Background: CAPTIM was a randomized trial comparing prehospital thrombolysis with transfer to an interventional facility (and, if needed, percutaneous intervention) with primary percutaneous coronary intervention (PCI) in patients with ST-segment-elevation myocardial infarction (STEMI). Because the benefit of thrombolysis is maximal during the first 2 hours after symptom onset, and because prehospital thrombolysis can be implemented earlier than PCI, this analysis studied the relationship between the effect of assigned treatment and the time elapsed from symptom onset.
Methods and results: Randomization within 2 hours (n=460) or > or =2 hours (n=374) after symptom onset had no impact on the effect of treatment on the 30-day combined primary end point of death, nonfatal reinfarction, and disabling stroke. However, patients randomized <2 hours after symptom onset had a strong trend toward lower 30-day mortality with prehospital thrombolysis compared with those randomized to primary PCI (2.2% versus 5.7%, P=0.058), whereas mortality was similar in patients randomized > or =2 hours (5.9% versus 3.7%, P=0.47). There was a significant interaction between treatment effect and delay with respect to 30-day mortality (hazard ratio 4.19, 95% CI 1.033 to 17.004, P=0.045). Among patients randomized in the first 2 hours, cardiogenic shock was less frequent with lytic therapy than with primary PCI (1.3% versus 5.3%, P=0.032), whereas rates were similar in patients randomized later.
Conclusions: Time from symptom onset should be considered when one selects reperfusion therapy in STEMI. Prehospital thrombolysis may be preferable to primary PCI for patients treated within the first 2 hours after symptom onset.