Clinical significance of residual ischaemia in acute myocardial infarction complicated by cardiogenic shock undergoing venoarterial-extracorporeal membrane oxygenation

Aims Although culprit-only revascularization during the index procedure has been recommended in patients with acute myocardial infarction (AMI) complicated by cardiogenic shock (CS), the reduction in residual ischaemia is also emphasized to improve clinical outcomes. However, few data are available about the significance of residual ischaemia in patients undergoing mechanical circulatory supports. This study aimed to evaluate the effects of residual ischaemia on clinical outcomes in patients with AMI undergoing venoarterial-extracorporeal membrane oxygenation (VA-ECMO). Methods and results Patients with AMI with multivessel disease who underwent VA-ECMO due to refractory CS were pooled from the RESCUE and SMC-ECMO registries. The included patients were classified into three groups according to residual ischaemia evaluated using the residual Synergy between percutaneous coronary intervention with Taxus and Cardiac Surgery (SYNTAX) score (rSS): rSS = 0, 0 < rSS <= 8, and rSS > 8. The primary outcome was 1-year all-cause death. A total of 408 patients were classified into the rSS = 0 (n = 100, 24.5%), 0 < rSS <= 8 (n = 136, 33.3%), and rSS > 8 (n = 172, 42.2%) groups. The cumulative incidence of the primary outcome differed significantly according to rSS (33.9 vs. 55.4 vs. 66.1% for rSS = 0, 0 < rSS <= 8, and rSS > 8, respectively, overall P < 0.001). In a multivariable model, rSS was independently associated with the risk of 1-year all-cause death (adjusted hazard ratio 1.03, 95% confidence interval 1.01-1.05, P = 0.003). Conversely, the baseline SYNTAX score was not associated with the risk of the primary outcome. Furthermore, when patients were stratified by rSS, the primary outcome did not differ significantly between the high and low delta SYNTAX score groups. Conclusion In patients with AMI with refractory CS who underwent VA-ECMO, residual ischaemia was associated with an increased risk of 1-year mortality. Future studies are needed to evaluate the efficacy and safety of revascularization strategies to minimize residual ischaemia in patients with CS supported with VA-ECMO. Clinical trial registration REtrospective and Prospective Observational Study to Investigate Clinical oUtcomes and Efficacy of Left Ventricular Assist Device for Korean Patients With Cardiogenic Shock (RESCUE), NCT02985008.