Prognostic significance of the discrepancy between STEMI/NSTEMI paradigm and the angiographically confirmed diagnosis of Occlusion Myocardial Infarction: a retrospective cohort study

<h2>Abstract</h2><h3>Background</h3> It is commonly assumed that acute total occlusion of the infarct-related artery corresponds to the diagnosis of ST-elevation myocardial infarction (STEMI), yet growing evidence suggests that the ST-elevation/non–ST-elevation myocardial infarction (NSTEMI) paradigm is inadequate for guiding emergency revascularization. <h3>Methods</h3> We conducted a retrospective study and assessed the association of occlusion/non-occlusion myocardial infarction (OMI/NOMI) angiographic diagnosis with short-term mortality, compared with the ECG diagnosis of STEMI/NSTEMI. Data from 1540 patients with acute myocardial infarction treated with percutaneous cardiac intervention (PCI) (68 % males, 40.3 % with initial diagnosis of STEMI, 51.6 % with final diagnosis of OMI) were analyzed. OMI was defined as MI with Thrombolysis In Myocardial Infarction (TIMI) 0–2 flow before revascularization. Primary aim was to compare 30-day mortality risk between NSTEMI-OMI and STEMI. <h3>Results</h3> Among patients initially identified as NSTEMI, 37.3 % had OMI. Although the infarct size as assessed by peak troponin hs-cTnT was smaller in NSTEMI-OMI than in STEMI patients (median (IQR): 17497.16 (3596.56–25,000.10) vs 25,000.1 (10,893.41–25,000.10) ng/L; p < 0.001) however, NSTEMI-OMI patients did not differ in 30-day mortality risk in comparison to STEMI patients (HR 0.75, 95 %CI 0.51–1.11, p = 0.146) and had significantly higher mortality risk than NSTEMI-NOMI patients (HR 2.4, 95 %CI 1.46–4.01, p = 0.001). <h3>Conclusions</h3> The high prevalence of OMI among NSTEMI patients and their unfavorable outcomes clearly demonstrate that the assessment of acute myocardial infarction should not rely solely on ST-segment elevation on admission ECG, as the STEMI/NSTEMI classification may miss patients with acute coronary occlusion who require urgent reperfusion.