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Many clinical trials have shown that primary percutaneous coronary intervention (PPCI) is more effective than thrombolysis for the treatment of ST-segment elevation myocardial infarction (STEMI).1 According to current guidelines, PPCI is the preferred form of reperfusion treatment for patients with STEMI. However, advantages of an invasive approach over fibrinolytic treatment may be blunted by several factors. Most important include low availability of experienced institutions offering 24 hour/7 day PPCI service and delay to invasive treatment due to prolonged transport. The delayed initiation of reperfusion treatment and its effect on clinical outcomes in STEMI and long-term mortality as well as logistic problems of the organisation of cardiac care have been extensively discussed.
In this issue of Heart, Asseburg et al present a meta-analysis of randomised studies comparing PPCI and fibrinolytic treatment for patients with STEMI (see article on page 1244).2 Of special interest is the application of Bayesian statistical methods for analysis of treatment efficacy with respect to PPCI-related delay. It is noteworthy that the analysis included 30-day and 6-month end points. The investigators demonstrated that the advantage of PPCI over fibrinolytic treatment was lost with increasing PPCI-related delay. Loss of the 6-month mortality advantage of PPCI over fibrinolytic treatment was observed for PPCI-related delay >90 minutes.
Occlusion of the infarct-related artery produces acute ischaemia, leading to progression of myocardial necrosis within several hours. A number of factors may affect progression of myocardial necrosis (completeness of coronary occlusion, presence of collaterals, preconditioning or an individual demand for myocardial oxygen). Despite the variability related to the factors mentioned above, duration of ischaemia remains the most important determinant of infarct size and myocardial damage.
TIME TO REPERFUSION AND CLINICAL OUTCOMES
Clinical trials of fibrinolytic agents have shown a significant relationship between symptom onset to reperfusion time and mortality. Earlier studies …