Recovery of myocardial function *1The ultimate target of coronary revascularization

Abstract

Recovery of myocardial contraction represents an important target of coronary revascularization and the preoperative recognition of viable akinetic (hibernating) myocardium is a crucial point of the preoperative investigation of patients with chronically depressed left ventricular function. In 14 patients dobutamine infusion during echocardiography was utilized to evoke the contractile reserve retained by viable akinetic segments. Redistribution of thallium(TI)-201 after the rest injection was also used to assess the viability of akinetic areas. The wall motion response to dobutamine infusion predicted immediate postoperative improvement in 85 of 93 segments (sensitivity 91.3%) and identified 25 of the 32 segments which did not exhibit early postoperative improvement (specificity 78.1%). Rest redistribution of TI-201 demonstrated high sensitivity (93.0%) but low specificity (43.7%) for predicting the early recovery of regional wall motion. When late recovery was also considered, the specificity of this method increased to 64.0%. Rest distribution of TI-201 identifies viability which is not necessarily associated with the early recovery of function postoperatively. When the echo-dobutamine test is positive, on the other hand, the recovery of function usually occurs immediately after revascularization and the operative risk is expected to be low even in the presence of severely compromised left ventricular function.

Time Course of Functional Recovery of Stunned and Hibernating Segments After Surgical Revascularization

“…3 However, the few available studies with longer follow-up have shown that a delayed recovery of function may occur. 4,5,17,18 Thus, the variance in recovery of function in the studies may (in part) be related to the time course of recovery after revascularization. The differences in time course of recovery may be related to the severity of ultrastructural damage before revascularization.…”

Impaired Coronary Flow Reserve Is the Most Important Marker of Viable Myocardium in the Myocardial Segment-Based Analysis of Dual-Isotope Gated Myocardial Perfusion Single-Photon Emission Computed Tomography

“…With regard to the detection of viable myocardium, the reversibility from the stress defect was considered to be equivalent to the reversibility from the rest defect. Therefore stress image acquisition was not always required for a viability assessment; the 201 Tl rest-redistribution study was considered sufficient for detection of viable myocardium (16, 17). …”

“…Third, individual viability markers may represent different phases during the progression of myocardial dysfunction and accordingly the time to full recovery after revascularization may differ. Dobutamine stress echocardiography has been reported to detect recovering dysfunctional myocardium just a few weeks after CABG (16). The dysfunctional myocardium with stress/rest reversibility mainly presented wall-motion improvement 3 months post-CABG (23).…”

Surgical methods to reverse left ventricular remodeling

“…Hibernating myocardium may recover its function with improved perfusion [7], further LV dilatation and dysfunction can be prevented, and the risk of sudden death is reduced [8]. Observational series suggest that patients with ischemic cardiomyopathy who are most likely to benefit from revascularization are those in whom a significant amount of viable myocardium (25% or more of the left ventricle) can be demonstrated preoperatively [9][10][11].…”