When treating ST-elevation myocardial infarction (STEMI) with primary percutaneous coronary intervention (PPCI) a successful restoration of coronary epicardial blood flow does not guarantee sufficient microvascular perfusion or optimal outcome. Thus, one-third of patients achieving thrombolysis in myocardial infarction flow grade 3 have compromised microvascular perfusion, which may have prognostic implications.1 Such patients nay be identified by single photon emission computed tomography, positron emission tomography or stress Echo. These methods, however, cannot help us in triaging per-interventional or early post-interventional treatment because they are not available 24-hourly, require skilled personnel for the interpretation and the results are not available until a time at which irreversible myocardial damage has occurred. ECG analysis, even though introduced more than 100 years ago,2 may provide valuable prognostic information even in the era of PPCI. It is well established that early and complete resolution of ST-segment elevation is a powerful predictor of infarct-related artery patency, preserved microvascular integrity and low mortality in patients with STEMI.3 However, there is no established consensus about how and when to measure ST resolution.

SHOULD WE MEASURE RELATIVE OR ABSOLUTE ST RESOLUTION?

Numerous potential ST-resolution measures may be of value in early risk stratification, evaluation of coronary epicardial patency and microvascular integrity (table 1). For some reason relative ST resolution is used in the majority of trials as a surrogate endpoint measure of …