Dobutamine stress-redisstribution-reinjection versus rest-redistribution thallium-201 spect in the assessment of myocardial viability.

The aim of this study was to evaluate the value of thallium-201 chloride (²⁰¹Tl) reinjection imaging following dobutamine stress (DRi) to identify viable myocardium in comparison with a rest-redistribution ²⁰¹Tl protocol (RR). The identification of viable myocardium bears important consequences for adequate selection of patients with poor left ventricular function, often unable to exercise, who are considered for revascularization. Twenty-six patients with chronic coronary artery disease and depressed left ventricular function (ejection fraction 36±10%) were studied by both DRi and RR single photon emission computed tomography (SPECT). Semi-quantitative analysis of regional ²⁰¹Tl activity (5-point score) and wall motion by echocardiography using a 16-segment model was performed. Regions were classified as viable (normal/reversible/fixed moderate defects) or non-viable (fixed severe defects) and related to regional wall motion. Target heart rate was reached in 25 patients. Myocardial viability was demonstrated in 353/416 (85%) by DRi SPECT and in 346/416 (83%) by RR SPECT. The agreement between the 2 protocols was 98% with a K-value of 0.94; similar results were obtained when the analysis was limited to dyscontractile segments. In conclusion, this study demonstrates the feasibility and diagnostic value of DRi SPECT to identify viable myocardium. [ABSTRACT FROM AUTHOR]