Impact of late reperfusion therapy in patients with inferior ST-segment elevation myocardial infarction and right ventricular dysfunction: one size never fits all

Abstract Background A significant proportion of ST-segment elevation myocardial infarction (STEMI) patients present late to the emergency room with limited evidence of benefit of reperfusion after 12 hours of symptom onset. Inferior myocardial infarction (MI) with right ventricle (RV) dysfunction is associated with high morbidity and mortality, however, the RV has a unique physiology that allows it to withstand ischemia better and recover faster. Purpose To compare adverse in-hospital cardiovascular events in latecomers with inferior STEMI and RV dysfunction admitted to a cardiovascular intensive care unit (CICU) from a low-to-middle-income country, who underwent late reperfusion treatment versus conservative treatment. Methods A retrospective cohort study was conducted from March 2022 to April 2023. Patients with inferior STEMI and RV dysfunction who received late reperfusion treatment were included. RV dysfunction was defined as a TAPSE <17 mm, tricuspid annular systolic velocity on TDI <9.5 cm/s, or a fractional area change <35%. Late reperfusion was defined as primary percutaneous coronary intervention (PCI) performed after 12 hours of symptom onset or rescue PCI after 12 hours of failed fibrinolysis. The primary outcome was in-hospital all-cause mortality. Secondary outcomes were cardiovascular death, reinfarction, stroke, cardiogenic shock, and mechanical complications. Results During the specified period, a total of 106 patients met the inclusion criteria from a total of 1,786 patients admitted to the CICU in our center. Only 60 patients underwent late PCI, accounting for 56% of the cases, with a median time of onset of symptoms to reperfusion of 19.4 hours (IQR: 15.7, 30.2). The average age was 66.5 ± 10.4 years, and 28% were women. Although the all-cause death rate was lower among late PCI group (13.3% vs 26.1%; p=0.096), this difference did not reach statistical significance in the bivariate analysis. Stratified by cardiogenic shock, a lower rate of all-cause mortality was also observed (33% vs 55%, p=0.15). The incidence of reinfarction was significantly lower in the late PCI group (0% vs 13%, p=0.004). In the multivariate analysis, adjusting for those who underwent PCI between 12-48 hours, revascularization of latecomers was independently associated with a significant reduction of mortality (adjusted OR 0.22; 95% CI 0.05-0.92; p=0.038). In a post-hoc analysis, late PCI showed a lower association with the composite outcome of all-cause mortality and reinfarction (adjusted OR 0.16, 95% CI 0.04-0.56; P=0.004). Conclusion(s) Our study demonstrates that implementing a reperfusion strategy in latecomers with inferior STEMI and RV dysfunction significantly reduces the risk of in-hospital mortality and reinfarction. This suggests a potential benefit of expanding the therapeutic window for PCI in this high-risk population. However, prospective studies are needed to conclude these preliminary findings.