Background Meta-analyses of trials comparing thrombolytics and primary angioplasty following myocardial infarction (MI) have shown benefits from angioplasty. Choice of therapy needs to consider the relationship between this benefit and any time delay in initiating angioplasty. Purpose. To extend earlier meta-analyses of these alternative forms of reperfusion by considering both 1- and 6-month outcome data. To use Bayesian statistical methods to quantify more fully the uncertainty associated with the estimated relationships.
Methods A systematic review and meta-analysis published in 2003 was updated with recently published trials. Data on key clinical outcomes and the difference between time-to-balloon and time-to-needle were independently extracted by two researchers. Bayesian statistical methods were used to synthesise evidence despite differences between trials in follow-up times and reported outcomes. Outcomes are presented as absolute probabilities of specific events and odds ratios (with 95% credible intervals (CrI)) as a function of the additional time-delay associated with angioplasty.
Results A total of 22 studies were included in the meta-analysis, with 3,760 and 3,758 patients randomised to primary angioplasty and thrombolysis, respectively. The mean angioplasty-related time delay (over and above time to thrombolysis) was 54.3 minutes (S.E. 2.2). For this average delay, the mean event probabilities are lower for primary angioplasty for all outcomes. Mortality within 1 month is 4.5% following angioplasty and 6.4% after thrombolytics (odds ratio of 0.68 (95% CrI 0.46, 1.01). For non-fatal re-infarction, the odds ratio is 0.32 (95% CrI 0.20, 0.51); and for non-fatal stroke it is 0.24 (95% CrI 0.11, 0.50). For all outcomes, the benefit of angioplasty decreases with longer delay until its initiation. In terms of mortality, angioplasty is superior, on average, at time delays up to around 90 minutes.
Conclusions The benefit of primary angioplasty, over thrombolysis, depends on the former's additional time delay. Even at delays longer than 1 hour, angioplasty is superior, on average, for all the outcomes, although these estimates are subject to uncertainty.
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