Differences on left ventricular remodeling between patients with or without myocardial viability after late recanalization after STEMI: a matched quasi-experimental design

Abstract Introduction In patients with ST- segment elevation myocardial infarction (STEMI), percutaneous coronary intervention (PCI) should be conducted within 12 hours of symptom onset regardless of viability status. The potential benefits attributable to late reperfusion in STEMI fall under the "open artery hypothesis" where the stunned peri-infarction zone after revascularization would restore blood supply and contractility.Purpose: To estimate the differences on the LV ejection fraction (LVEF) and indexed LV end-systolic volume (iLVESV) in patients with STEMI in whom a late coronary angioplasty was performed between 24 hours and 28 days after the event, exposed to their myocardial viability. Methods Forty-four non-reperfused patients with STEMI within 24 hours to 28 days underwent cardiac magnetic resonance (CMR) to assess myocardial viability from September 2021 to June 2022. Patients were classified as viable if they had at least 2 segments of the affected wall with less than 50 percent of left ventricular wall thickness with late gadolinium enhancement (LGE). Otherwise, they were classified as non-viable. All of them underwent angioplasty with drug-eluting stent and repeated CMR at 6 and 12 months to assess LVEF and iLVESV. This abstract presents a non-planned interim analysis of the 6-months results (N=44). Descriptive statistics were present by central and dispersion estimators, or absolute and relative frequencies. To estimate the differences between groups and time, a generalized mixed model (mixed-GEE) was run, and results were given as point-estimates and confidence intervals at 95% (95%CI). A significance level of 5% was adopted for inferential analysis. The study has local IRB approval and was registered at ClinicalTrials.gov prior to its recruitment NCT05160311. Results 44 patients (57±9 years old, 11 women) were included in the study. Of them, 21 were classified as non-viable. Among comorbidities, patients usually were less exposed to any CV risk factor, exceptionally for hypertension (69% vs. 31%). At the end of the follow-up 90.1% of the patients were under optimized treatment with no differences between groups. The difference on LVEF at baseline and in 6 months for the non-viable and viable group was of 4.48% and 4.67% respectively (P=0.08 for time, P=0.001 for viability status and P=0.97 for interaction). For LVESV, we found an estimate of 0.80 mL/m2 and 0.90 mL/m2 (P=0.86 for time, P=0.003 for viability status and P=0.991 for interaction). More detailed results can be found at Table 1. Conclusion We conclude that was no evidence for difference either for LVEF and iLVESV within and between groups. The aforementioned parameters did not reach statistical significance for their improvement, although they presented similar magnitude.Table 1