The Occluded Artery Trial (OAT) Viability Ancillary Study (OAT-NUC): Influence of Infarct Zone Viability on Left Ventricular Remodeling After Percutaneous Coronary Intervention Versus Optimal Medical Therapy Alone
What is the influence of retained infarct zone (IZ) viability on extent of left ventricular (LV) remodeling in post–myocardial infarction (MI) patients with occluded infarct-related artery (IRA)?
The OAT nuclear ancillary study hypothesized that 1) IZ viability influences LV remodeling, and that 2) PCI as compared with optimal medical therapy (MED) attenuates adverse remodeling in post-MI patients with preserved viability. Enrolled were 124 OAT patients who underwent resting nitroglycerin-enhanced technetium-99m sestamibi single-photon emission computed tomography (SPECT) before OAT randomization, with repeat imaging at 1 year. All images were quantitatively analyzed for infarct size, IZ viability, LV volumes, and function in a core laboratory. The primary endpoint of LV remodeling was assessed by change in LV end-diastolic volume from baseline to 1 year. To evaluate the influence of retained IZ viability on extent of LV remodeling, changes in LV volumes and ejection fraction were compared by baseline viability.
At baseline, mean infarct size was 26% ± 18 of the LV, mean IZ viability was 43% ± 8 of peak uptake, and most patients (70%) had at least moderately retained IZ viability. There were no significant differences in 1-year end-diastolic or end-systolic volume change between those with severely reduced versus moderately retained IZ viability, or when compared by treatment assignment PCI versus MED. In multivariable models, increasing baseline viability independently predicted improvement in ejection fraction (p = 0.005). There was no interaction between IZ viability and treatment assignment for any measure of LV remodeling.
The authors concluded that in the contemporary era of MED, PCI of the IRA compared with MED alone does not impact LV remodeling irrespective of IZ viability.
The results of this study suggest that in stable patients studied in the subacute phase post-MI with a totally occluded IRA, there is no influence of baseline IZ viability on the extent of LV remodeling at 1 year. Furthermore, there was no benefit of PCI on 1-year change in ejection fraction or volumes and no interaction between the degree of retained viability and the extent of remodeling in patients randomized to PCI versus MED. Overall, the data do not support delayed revascularization post-MI irrespective of IZ viability.
Keywords: Heart Diseases, Myocardial Infarction, Cardiology, Heart Failure, Percutaneous Coronary Intervention
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