The electrocardiographic window of opportunity to treat vs. the different evolving stages of ST-elevation myocardial infarction: correlation with therapeutic approach, coronary anatomy, and outcome in the DANAMI-2 trial

Abstract

The aim of the study was to assess two distinct 12-lead electrocardiogram (ECG) patterns and their prognostic value with respect to reperfusion strategy. In a DANAMI-2 substudy (n = 1522), we defined the pre-infarction syndrome (PIS) as ST-elevation accompanied by positive T waves and evolving myocardial infarction (EMI) as pathological Q waves and/or negative T wave. We used a composite of death, clinical re-infarction, or disabling stroke at median 2.7 year follow-up. A higher overall event rate was observed in the EMI group compared with the PIS group [11.4 (9.4-13.9) and 6.9 (6.0-8.0) per 100 person-years, respectively, ratio of the rate (RR) 1.6, P < 0.001]. The EMI pattern was independently predictive of adverse outcome in multivariable analysis (hazard ratio 1.52, confidence interval 1.01-2.30, P = 0.04). The PIS pattern (n = 952) was associated with lower overall event rate in patients treated with primary percutaneous coronary intervention (PCI) compared with fibrinolytic therapy (FT) [5.5 (4.4-6.9) and 8.5 (7.0-10.4) per 100 person-years, respectively, RR = 0.6, P = 0.004]. No significant difference in the outcome between treatment strategies was observed in the EMI group as a whole. However, in patients with anterior EMI without ECG signs of reperfusion, superiority of primary PCI was driven by a 51% reduction in the relative risk of composite endpoint (P = 0.008). More detailed ECG analysis, involving also Q- and T-wave morphology, is useful for rapid identification of high-risk patients in whom every effort should be made to transfer for primary PCI, or vice versa, for identifying low-risk patients in whom FT might be an alternative option.