Myocardial viability estimation during the recovery phase of stress echocardiography after acute beta-blocker administration
Background: Myocardial viability assessment in severely dysfunctional segments by dobutamine stress echocardiography (DSE) is less sensitive than nuclear scanning. Aim: To assess the additional value of using the recovery phase of DSE after acute beta-blocker administration for identifying viable myocardium. Methods: The study included 49 consecutive patients with ejection fraction (LVEF) ≤ 35%. All patients underwent DSE evaluation at low-high dose and during recovery phase, and dual-isotope single photon emission tomography (DISA-SPECT) evaluation for viability of severely dysfunctional segments. Patients with ≥ 4 viable segments were considered viable. Coronary revascularization followed within 3 months in all patients. Radionuclide evaluation of LVEF was performed before and 12 months after revascularization. Results: Viability with DISA-SPECT was detected in 463 (59%) segments, while 154 (19.7%) segments presented as scar. The number of viable segments increased from 415 (53%) at DSE to 463 (59%) at DSE and recovery, and the number of viable patients increased from 43 to 49 respectively. LVEF improved by ≥ 5% in 27 patients. Multivariate regression analysis showed that, DSE with recovery phase was the only independent predictor of ≥ 5% LVEF improvement after revascularization (OR 14.6, CI 1.4-133.7). Conclusion: In this study, we demonstrate that the recovery phase of DSE has an increased sensitivity for viability estimation compared to low-high dose DSE.