Myocardial Viability Assessment: Role of Dobutamine Echocardiograohy and Tetrofosmin Gated SPECT

Abstract

Objective: Myocardial viability assessment is an essential step to identify patients who may improve after revascularization. The aim of this study is evaluation of dobutamine echocardiography and Tc-99m tetrofosmin gated SPECT in the assessment of myocardial viability compared to the current gold standard; thallium-201 gated SPECT. Patients andMethods: This prospective study included 35 consecutive patients with asynergy or low ejection fraction (EF) < 50% on resting echocardiography. The myocardial viability of all patients was tested with threetechniques; Dobutamine Echocardiography, Tetrofosmin SPECT and the gold standard; 201-Tl SPECT (restredistribution study).Results: The mean age of the studied group was 53.4±9.1 years. (1 female and 34 males) Dobutamine Echo identified 156 viable segments. Its Sensitivity and specificity were 30.1% and 83.5%, respectively. 99mTc-tetrofosmin gated SPECT detected 484 viable segments. Sensitivity and specificity were 96.6% and 94.9, respectively. There was no agreement between dobutamine echo and 201Tl SPECT (kappa = 0.057) or99m Tc-tetrofosmin gated SPECT (kappa= 0.055). Tetrofosmin SPECT and 201 - Tl SPECT showed outstanding agreement in assessment of myocardial viability (kappa = 0.890). Echomeasured EF was significantly higher than EF estimated by Tetrofosmin SPECT (p = 0.01) and 201Tl SPECT (p = 0.02). The latter two methods were not significantly different in estimation of EF (p = 1.000).Conclusion: For evaluation of myocardial viability, dobutamine echocardiography is a good positive test;99mTc tetrofosmin is a better sensitive marker of myocardial viability compared to 201Tl SPECT. We recommend starting with dobutamine echo (no radiation exposure) with PPV of 90% to detect viability. For negative dobutamine results we can proceed to 99mTcsestamibi or tetrofosmin SPECT with 97% sensitivity.