Detection of viable tissue in healed infarcted myocardium by dipyridamole thallium-201 reinjection and regional wall motion studies.

Reinjection imaging with thallium-201 (Tl-201) may provide a convenient method of assessing myocardial viability. Twenty patients with a previous Q-wave healed myocardial infarction were examined to evaluate the detection of viable tissue in infarcted segments. All patients underwent to evaluate the detection of viable tissue in infarcted segments. All patients underwent dipyridamole Tl-201 tomographic imaging with reinjection of 1 mCi of Tl-201 after redistribution. Radionuclide ventriculography was performed before and after administration of 5 mg of dinitrate isosorbide sublingually for regional wall motion analysis. Patients presented with 38 fixed defects, 12 of which demonstrated improved Tl-201 uptake on reinjection; 10 of 12 reinjection-reversible segments were hypokinetic or normal after administration of nitrates, whereas 22 of 26 nonreversible segments remained akinetic or dyskinetic (p < 0.001). Of 20 patients, 9 had reinjection-reversible segments; coronary angiography revealed a patent infarct-related artery or collaterals, or both, in 7 of these patients. The infarct-related artery was patent or collaterals were present, or both, in 4 of 11 patients who did not improve with reinjection. It is concluded that reinjection of Tl-201 during dipyridamole Tl-201 scintigraphy may frequently detect viable tissue in infarcted segments in patients with a Q-wave infarction. Segments with reinjection reversibility usually do not remain dyskinetic or akinetic after administration of nitrates and have some residual flow on coronary angiography.