Assessment of the right ventricular ischemia by means of stress T1-201 myocardial imaging

In order to evaluate the clinical significance of thallium (Tl)-201 myocardial imaging for diagnosing the right ventricular (RV) ischemia, relationship of right ventricular free wall (RVFW) appearance on myocardial images to coronary arteriographic findings was studied. Patients were divided into 3 groups as follows: 1) normal control (NC) group (19 cases) without angiographically documented coronary artery disease; non-RCA group (18 cases) with significant coronary artery lesion restricted to the left coronary artery (LCA); and 3) RCA group (41 cases) with significant right coronary artery (RCA) stenosis regardless of underlying LCA disease. On the immediate images, all patients except one in the NC group and all except 4 in the non-RCA group demonstrated ''continuous visualization'' of the RVFW in both views. In the RCA group, 6 showed ''non-visualization'' and 13 ''defective visualization'' of the RVFW in 300 LAO view. In 600 LAO view, 6 presented ''non-visualization'' and 7 ''defective visualization'' of the RVFW. On the delayed images, although none of the patients in the groups NC and non-RCA demonstrated redistribution phenomenon of the RVFW, 5 patients in the RCA group showed redistribution of Tl-201 into the RVFW. When abnormal RVFW findings were defined as ''non-visualization'' or ''defective visualization'' of the RVFW on immediate images and/or positive redistribution phenomenon of the RVFW, sensitivity and specificity of the RVFW findings on stress Tl-201 myocardial images for detection of the RCA disease were 48.8% and 94.8%, respectively. Non- and defective visualization of the RVFW on the immediate images were related to the proximally located RCA lesion, previous history of inferior MI and high grade RCA stenosis. Collateral vessels seemed to protect the RVFW against the development of exercise induced ischemia and affect the occurrence of redistibution of Tl-201 into the RVFW. (J.P.N.)