Myocardial viability, which definition should we depend upon role of radionuclide imaging

ABSTRACT

Rest-redistribution thallium [RD T1] imaging has high negative predictive value [NPV] but low positive predictive value [PPV] for the prediction of recovery of regional myocardial dysfunction after revascularization [R]. Combining perfusion [MP] and functional data with nitrate-enhanced gazed SPECT MIBI [GSM] at rest appears to be a promising approach for viability detection. Differentiate between the role of resting TL and resting GSM for detection of viability. 66 pts with coronary artery disease [CAD] underwent T1 imaging [R-RD protocol], 2 sets of resting GSM using 2 MIBI injections, and echocardiography, both at rest and after low dose dobutamine [LDD]. One hour Before GSM2, 60 mg. of oral trimetazidine [TMZ] and nitrates had been given. All pts had their echos repeated after [R]. Perfusion and wall motion [WM] were scored from 0 to 4 [absent to normal] using 17 segment model. 385/1122 segments were found to have abnormal resting WM on echo. 165/217 of the hypokinetic segments, 48/102 of the akinetic segments and 6/66 of the dyskinetic segments showed contractile response for LDD echo. The MP images showed normal uptake, complete, partial reversibility and poor uptake in TI, GSM1 and GSM2 images as following [54, 31, 45], [36, 22, 35], [198, 119, 190] and [32, 148, 50] of segments respectively. Following table showed degree of matching. Sensitivity and specificity of T1, GSM1 and GSM2 and LDD echo had been found respectively to be [94.9%, 75.5%], [60%, 93.6%], [94.2%, 90%] and [79.6%, 100%]. Post-revascularization Resting Echocardiography -, -, Viable, Non-Viable, -, Viable, Non-Viable, -, Viable, Non-Viable, -, Viable, Non-Viable. Pre-revascularization Viable- Non-Viable, Rest-Redistribution Thallium, 261- 14, 27- 83, Non-TMZ gated SPECT, 165- 110, 7- 103, TMZ gated SPECT, 259- 16, 11- 99, LDD Echocardiography, 219- 56, 0- 110. Total -, -, 275, 110, -, 275, 110, -, 275, 110, -, 275, 110. Clinical definition of viability is better looked for in GSM2