Initial and delayed right ventricular thallium-201 rest-imaging following dipyridamole-induced coronary vasodilation: Relationship to right coronary artery pathoanatomy

The relationship of coronary anatomy to right ventricular (RV) appearance on serial thallium-201 myocardial imaging (TI) following dipyridamole (DP)-induced coronary vasodilation was examined in 71 consecutive patients undergoing coronary angiography for the evaluation of chest pain. Transient defects of the RV were found in 18 patients. All 18 had significant (≥ 50%) stenosis of the proximal right coronary artery (RCA). Nonvisualization of RV activity occurred in 13 patients. Six of these 13 (46%) had proximal RCA disease (p < 0.05 compared to transient defects). Normal RV appearance was seen in 40 patients, of whom only six (15%) had proximal RCA disease (p < 0.001 compared to transient defects). RV appearance was not affected by left anterior descending or left circumflex artery disease or by the thallium-201 uptake in the left ventricle. Thus with serial (initial and delayed) TI following DP (1) a transient RV defect appears to indicate significant proximal RCA disease; (2) normal RV appearance suggests the absence of proximal RCA disease; and (3) however, nonvisualization of the RV appears to be nondiagnostic.