Time delay-adjusted survival benefit of angioplasty over thrombolysis in acute myocardial infarction: influence of time from symptom onset

BACKGROUND: The time-to-treatment is a critical determinant of outcome after acute myocardial infarction. We investigated the relationship between the primary angioplasty (PCI)-related time delay and the benefit of PCI over thrombolytic therapy (TT), considering the time elapsing from symptom onset in 21 randomized trials comparing PCI to TT. METHODS: PCI-related time delay was calculated as the median of the "door-to-balloon" time minus the median of the "door-to-needle" time. The survival benefit was defined as the difference between 30-day mortality after TT and after PCI. The relationships between time delay and benefit were assessed by linear regression. RESULTS: PCI-related time delay ranged from 7 to 104 min. Linear regression showed that at a PCI-related delay of 75 min, PCI and TT yielded equivalent reductions in mortality (p = 0.03). When the trials with the longest and shortest delays were excluded, the benefit of PCI over TT was nullified after a delay of 62 min, and every additional 10-min delay produced a 1.1% increase in mortality (p = 0.01). When trials with a symptom duration < 6 hours (median 130 min) were considered, PCI-related delay still correlated with an absolute risk reduction in 30-day mortality with a time to equipoise of 57 min (p = 0.03). Lack of correlation (p = 0.85) was observed in trials enrolling patients within 12 hours of symptom onset (median 185 min). CONCLUSIONS: Our analysis suggests that PCI-related delay substantially modifies the benefit of PCI over TT, particularly in case of patients presenting early following symptom onset