Postinfarction left-ventricular aneurysm: regional stress, function, and remodeling after aneurysmectomy

Abstract

Background: Left-ventricular (LV) aneurysm formation after myocardial infarction (MI) leads to LV remodeling with global and regional cardiac dysfunction. LV aneurysmectomy (LVA) can often improve LV function, but changes of regional wall stress and systolic function in the noninfarcted segment before and after the operation remain poorly understood. The purpose of this study was to assess the effects of LVA on regional stress and systolic function in the noninfarcted region and to examine this procedure's impact on the LV remodeling in patients with LV aneurysm after myocardial infarction (MI).

Methods: Using quantitative left ventriculography and pressure measurements, 11 patients with an anterior LV aneurysm were studied before and 8 months after standard linear repair (LVA group), and 10 patients with an anterior transmural infarction who received coronary artery bypass grafting were also studied (CABG group) in an attempt to separate the effects of aneurysmectomy from the effects of bypass surgery. Regional end-systolic (ESS) and end-diastolic (EDS) stresses of the contractile segment (CS) were computed by Janz's method.

Results: The total ejection fraction (EF) increased (p < 0.01) in the LVA group, whereas it did not change in the CABG group at 8 months after surgery. Both the end-diastolic and end-systolic volume indices of CS decreased (p < 0.01 and p < 0.01, respectively) in the LVA group, whereas both remained unchanged in the CABG group. The mean velocity of circumferential fiber shortening (mean Vcf) of CS increased substantially (p < 0.01) in the LVA group and, less significantly (p < 0.05), in the CABG group. Regional ESS and EDS decreased (p < 0.01 and p < 0.05, respectively) in the LVA group, whereas both remained unchanged in the CABG group. The increase in mean Vcf correlated strongly with the magnitude of decrease in ESS (r = -0.63, p < 0.01) in the LVA group but not in the CABG group.

Conclusions: LVA can reduce regional afterload and improve ejection performance of the noninfarcted myocardium in many patients with a large anterior LV aneurysm and, moreover, may favorably affect the LV remodeling process after MI.