Time for a DIagnostic Paradigm Shift From ST-elevation/Non-ST-elevation to OCClUsion/Non-occLusion Myocardial infarcTion

I. BACKGROUND AND SIGNIFICANCE

The patients with acute coronary occlusion (ACO) or potentially imminent occlusion, with insufficient collateral circulation, have myocardium that is at risk of infarction unless they undergo immediate reperfusion via thrombolytics or percutaneous coronary intervention (PCI). One of the most important tasks in emergency cardiology is to immediately identify acute coronary occlusion (ACO) myocardial infarction (OMI) among all patients who present with symptoms compatible with acute myocardial infarction (MI), and distinguish them from those without MI, and from those with MI that does not have ongoing myocyte loss (Non-OMI, or NOMI) who can be managed with medical therapy and for whom potentially harmful invasive interventions can be deferred. The electrocardiogram (ECG) plays a central role in this process.

The presence or absence of ST-segment elevation (STE) is principally used to define patients who need emergent coronary revascularization, since subgroup analyses of the Fibrinolytic Therapy Trialists' (FTT) meta-analysis indicated that patients with STE on ECG gain a slightly better survival benefit from emergent reperfusion. After fine-tuning of STE cutoffs used in this analysis, universally agreed STEMI criteria became the current guideline-supported ECG paradigm.

It is not clear why a disease of a known pathophysiology (ACO) was named with an inaccurate surrogate ECG sign (Q-wave MI/non-Q-wave MI or STEMI/non-STEMI) instead of the pathologic substrate itself (ACO-MI/non-ACO-MI or OMI for short), but this fundamental mistake created important implications for our current practice. As briefly outlined above, ACO can be reliably recognized with the help of many other ECG findings, such as minor STE not fulfilling STEMI criteria, STE disproportionate to preceding QRS, unusual patterns with contiguous leads showing opposite ST deviations and some patterns not showing STE at all.

Recently, the DIagnostic accuracy oF electrocardiogram for acute coronary OCClUsion resuLTing in myocardial infarction (DIFOCCULT) study, compared OMI/non-OMI approach with STEMI/non-STEMI paradigm. This is the largest study specifically designed to question the STEMI/non-STEMI paradigm, in which a set of predefined ECG findings in addition to STEMI criteria were used, and the final outcome was a composite ACO endpoint. In accordance with the previous observations, over one-fourth of the patients initially classified as having non-STEMI were re-classified by the ECG reviewers, blinded to all outcome data, as having OMI. This subgroup had a higher frequency of ACO, myocardial damage, and both in-hospital and long-term mortality compared to the non-OMI group. The OMI/non-OMI approach to the ECG had a superior diagnostic accuracy compared to the STE/non-STEMI approach in the prediction of both ACO and long-term mortality.