Ischemia modulation via coronary revascularization and effects on the arrhythmic substrate

Coronary revascularization is frequently undertaken to reduce ischemia in patients with ischemic left ventricular (LV) dysfunction. Whether revascularization modulates the substrate for ventricular arrhythmia is unclear.

The study aimed to assess the effects of revascularization on arrhythmic substrate in ischemic LV dysfunction and the association of the latter with changes in ischemia and scar.

Patients were enrolled if they had a LV ejection fraction (LVEF) ≤40%, extensive coronary disease (British Cardiovascular Intervention Society jeopardy score >6/12) and were scheduled to undergo percutaneous coronary intervention or coronary artery bypass surgery. Scar and ischemic burden were assessed via stress-perfusion cardiac magnetic resonance, calculated as a percentage of total LV myocardial volume. Arrhythmic substrate was characterized by non-invasive electrocardiographic imaging metrics, primarily LV activation recovery interval (ARI). Electrocardiographic imaging and perfusion cardiac magnetic resonance were repeated 3 months after revascularization. The primary outcome was change in LV ARI dispersion.

Of 30 patients (age 67 ± 10 years, 87% male, LVEF 29 ± 7%), 12 (40%) underwent coronary artery bypass surgery, 18 (60%) had percutaneous coronary intervention. Following revascularization, LVEF increased (+8 ± 8%), ischemic burden reduced (-34 ± 24%), P < .01) and scar burden was unchanged. Mean LV ARI dispersion was unchanged; however, individual changes in LV ARI dispersion correlated with individual changes in ischemic burden (r = 0.51, P < .01). LV volumes and scar burden at baseline and change in indexed LV end-systolic volume and ischemia predicted improvement.

Arrhythmic substrate correlated with scar burden and was unaltered by revascularization in this cohort. There was marked heterogeneity in residual ischemia which correlated with residual arrhythmic substrate. Further work is needed to personalize risk stratification in relation to ischemia reduction and residual arrhythmic risk.