Recovery of Left Ventricular Twist and Left Ventricular Untwist Rate in Patients with ST-segment Elevation Acute Myocardial Infarction

Abstract

Background: Left ventricular (LV) functional recovery and morphological remodeling after acute myocardial infarction (AMI) followed by reperfusion remain incompletely understood. The aim of the study was to describe the recovery of LV twist (LVT) and LV untwist rate (LVUR) upon revascularization after AMI using two-dimensional (2D) speckle tracking. Methods: We evaluated 88 subjects: 22 normal volunteers (mean age 31 ± 5 years), and 66 patients with AMI (mean age 65 ± 12 years), of which 40 had an inferior AMI and 26 an anterior one. All AMI patients had ST-segment elevation. Echocardiography was performed in all subjects. Patients were scanned within 36 h (baseline) after revascularization (percutaneous coronary intervention) and after 4 months (4 mFU). Apical and basal short-axis images were acquired (frame rate 67 ± 5 frames/s) and analyzed offline to extract the rotation (rate) curves. From these, maximal systolic LVT and peak LVUR were derived. Finally, the infarct size (IS) was estimated based on magnetic resonance imaging delayed enhancement and expressed as a percentage of the total LV volume. Results: At 36 h, LVT and LVUR were significantly reduced in both AMI groups when compared to normals. At 4 mFU, both AMI groups showed recovery in ejection fraction (EF) and reduction in IS (7.24 ± 10.07 vs. 20.13 ± 13.9, P < 0.0001 for inferior AMI and 13.13 ± 10.3 vs. 24.40 ± 15, P < 0.0001 for anterior AMI). LVT and LVUR increased significantly but remained below normal levels. Correlation of LVT and LVUR with IS was significant, but weak (r = 0.34 and r = 0.34, respectively). In addition, a fair correlation of LVT with EF (r = 0.64) and a weak correlation of LVUR with end-diastolic volume (r = 0.43) were found. Conclusion: LVT and LVUR are reduced in AMI patients early after reperfusion and recover incompletely upon follow-up. Interestingly, recovery of LVT characteristics as measured with this 2D speckle tracking-based method showed to be independent of infarct location or extent. LVT and LVUR might be good parameters to monitor the recovery of global LV function after treatment.