Regional Left Ventricular Wall Stress Post-Myocardial Infarction with Magnetic Resonance Imaging in Swine.

This study presents a novel approach to measure regional left ventricular (LV) wall stress using Cardiac Magnetic Resonance (CMR) imaging. We studied a chronic heart failure (CHF) model in Yucatan mini swine. Animals underwent 90-minute balloon occlusion and reperfusion of the left anterior descending (LAD) coronary artery. LV pressures were measured using solid-state micromanometer pressure-tipped catheters. End-systolic elastance, end-diastolic pressure-volume relationships, and CMR imaging were collected at baseline and one-month post-myocardial infarction (MI). One month post-MI, data showed reduced LV function with increased end-systolic volume, end-diastolic volume, LV myocardial mass, and reduced ejection fraction. Hemodynamic data showed no significant changes in heart rate, LV pressures, tau, or dP/dt. However, end-systolic elastance decreased significantly (1.8 ± 0.2 to 1.1 ± 0.1, P < 0.05), indicating reduced LV contractility. Regional LV wall stress calculations revealed increasing trends in anterior septal (anteroseptal) and posterior lateral (posterolateral) end-systolic wall stress (ESWS). Anteroseptal ESWS increased from 10.1 ± 2.0 kPa to 20.0 ± 3.3 kPa (P < 0.05), while posterolateral ESWS increased from 6.8 ± 0.3 kPa to 11.7 ± 1.4 kPa (P < 0.05). This study demonstrates the benefit of a regional approach to LV wall stress assessment. Our findings revealed significant changes in both the anteroseptal (involved) and posterolateral (uninvolved) regions, suggesting a widespread impact of localized injury. Regional wall stress calculations can assess cardiac damage and provide prognosis of injury extent, potentially offering insights into global LV remodeling post-MI.