Transferring Patients With ST-Segment Elevation Myocardial Infarction for Mechanical Reperfusion: A Meta-Regression Analysis of Randomized Trials

Study objective: Primary angioplasty is associated with benefits in survival as compared with thrombolysis among patients with ST-segment elevation myocardial infarction (STEMI). However, in daily practice only a minority of STEMI patients are admitted to 24-hour primary percutaneous coronary intervention hospitals. A previous meta-analysis failed to show significant benefits in terms of survival, potentially because of a limited statistical power. Thus, the aim of the current study is to perform an updated meta-analysis of randomized trials to evaluate whether transfer for primary angioplasty provides significant benefits in terms of survival compared with on-site thrombolysis among STEMI patients. Methods: The literature was scanned by formal searches of electronic databases (MEDLINE, CENTRAL, EMBASE) and the Cochrane Central Register of Controlled trials (http://www.mrw.interscience.wiley.com/cochrane/Cochrane_clcentral-articies-fs.html) from January 1990 to April 2008. The following key words were used: "randomized trial;" "myocardial infarction;" "reperfusion;" "thrombolysis;" "primary angioplasty;" "angioplasty;" "mechanical reperfusion;" "facilitation;" "transfer;" "transportation;" "mortality;" and "survival." Inclusion criteria were (1) randomized comparison between on-site thrombolysis and transferring for primary angioplasty; and (2) complete data on mortality. We did not exclude trials or trial arms that specifically addressed transfer for percutaneous coronary intervention after thrombolysis. Crude data were extracted by 2 investigators. No language restrictions were enforced. The relationship between benefits in mortality and reinfarction, baseline mortality of the thrombolytic group in each study (study level variable), and percutaneous, coronary intervention-related time delay was evaluated by using a weighted least-square regression. Results: A total of 11 randomized trials were identified, including 5,741 patients (51.8% transferred for primary angioplasty and 48.2% treated with thrombolysis). Transfer for primary angioplasty was associated with a significant reduction in mortality (5.6% versus 6.8%; P = .02), reinfarction (2.1% versus 4.7%; P < .0001 and stroke (0.7% versus 1.7%, P = .0005) at 30-day follow-up. The benefits in mortality and reinfarction of transfer for primary percutaneous coronary intervention over thrombolysis were not significantly related to baseline mortality of the lytic group or to percutaneous coronary intervention-related time delay. Conclusion: This meta-analysis demonstrates that, among STEMI patients, transfer for mechanical reperfusion is associated, in addition to benefits in reinfarction and stroke, with a significant reduction in mortality at 30-day follow-up. [Ann Emerg Med. 2008;52:665-676.]