ST-resolution and spontaneous reperfusion in patients with transient ST-segment elevation myocardial infarction

This commentary refers to ‘Transient ST-segment elevation and coronary flow’, by R. Coronel et al., on page 2463. Coronel et al. 1 describe two theories why ST-resolution might not always coincide with coronary reperfusion in patients with ST-segment elevation myocardial infarction (STEMI). These theories are highly interesting but based on few experimental in vitro observations and were never replicated in patients. The first theory is based on a decreasing potassium concentration in the infarct border zone, leading to normalization of TQ-depression (ST-elevation) during ongoing acute ischaemia. It should be noted that the presented signal (Figure A) was derived from one out of 64 electrodes placed directly in the infarct border. This is difficult to compare with a 12-lead surface electrogram and in fact signals were very inhomogeneous.2 The second theory is based on a mechanism demonstrated in isolated heart muscle strips from toads, whereby the injury current is abated because over time gap junctions between myocytes close.3 It can be postulated that this is part of ST-resolution as seen in every non-reperfused STEMI over time. In patients, however, this takes at least several hours, in contrast to above mentioned muscle preparation. Many theories based on bench results unfortunately cannot be extrapolated to bedside. In the bedside reality of the TRANSIENT trial only three patients were found to have thrombolysis in myocardial infarction (TIMI) flow 0-1 at the time of coronary angiography. All of these patients showed signs of re-infarction, with recurrence of symptoms and ST-segment elevation. Therefore, transient STEMI coincided with an open artery in 100% of cases in our population.4 Our findings are in accordance with another study that investigated impaired endogenous fibrinolysis in STEMI patients, in which also all patients with spontaneous ST-resolution were found to have TIMI 2–3 flow at the time of immediate coronary angiography.5 We appreciate the proposed theories which deserve further investigation but should not influence clinicians in their decision making on the treatment strategy in patients with transient STEMI. Conflict of interest: none declared.