Determining myocardial viability in chronic ischemic left ventricular dysfunction: A prospective comparison of rest-redistribution thallium 201 single-photon emission computed tomography, nitroglycerin-dobutamine echocardiography, and intracoronary myocardial contrast echocardiography

Background: Detection of viable myocardium (VM) has important therapeutic implications for chronic ischemic left ventricular (LV) systolic dysfunction. We compared the ability of nitroglycerin-dobutamine echocardiography (NTG-DE), intracoronary myocardial contrast echocardiography (MCE), and rest-redistribution thallium 201 single-photon emission computed tomography (RRT-SPECT) to detect VM in this setting. Methods: Patients with LV ejection fraction (LVEF) <40% and multivessel coronary disease suitable for revascularization underwent NTG-DE, MCE, RRT-SPECT, and radionuclide ventriculography to determine baseline LVEF. Myocardial contrast echocardiography was performed using intracoronary injection of Albunex. Patients who underwent revascularization had 3-month postprocedural radionuclide ventriculography and transthoracic echocardiography to assess functional recovery. Results: Of 512 myocardial segments in the 32 patients studied, 309 were akinetic or dyskinetic at baseline. Nitroglycerin alone increased regional thickening in 20% of segments with contractile reserve. By RRT-SPECT, 93% of nitroglycerin-responsive segments were viable. Myocardial contrast echocardiography had up to 85% sensitivity and 74% specificity for detection of VM diagnosed by RRT-SPECT. In the 23 patients who underwent revascularization, 54% of akinetic segments showed improved contractility, and mean LVEF increased from 32% to 37% (P = .04). Sensitivities and specificities for detecting functional recovery were 95% and 37% for RRT-SPECT, up to 87% and 48% for MCE, and 63% and 83% for a biphasic response during NTG-DE. Conclusions: In patients with chronic ischemic LV dysfunction, RRT-SPECT had the highest sensitivity, and NTG-DE, the best specificity for detection of VM. Nitroglycerin facilitated detection of VM and may be a useful adjunct to dobutamine stimulation.