Assessment of right ventricular ejection fraction during exercise in coronary artery disease by multiple-gated equilibrium scintigraphy using continuous infusion of 81mKr

To study the effect of location of coronary artery lesions on right ventricular (RV) function, exercise 81mKr multiple gated equilibrium scintigraphy was performed in 35 patients with coronary artery disease and 12 control subjects. Thirty five patients were divided into three groups: group I; those without right coronary artery (RCA) stenosis (n=16), group II; those with stenosis of RCA distal to the origin of the major RV branch (n=8) and group III; those with proximal RCA stenosis (n=11). RV ejection fraction (RVEF) at rest was not significantly different among four groups. However, increase of RVEF during supine bicycle exercise was markedly suppressed in group III compared with any other three groups. Abnormal RVEF response to exercise was seen in all 11 cases of group III and five of eight cases of group II, while only two of 16 cases of group I showed abnormal RVEF response. Five of seven cases which demonstrated abnormal RVEF response without proximal RCA stenosis had multiple coronary vessel disease. On the other hand, the left ventricular (LV) response was more suppressed in group II than in group III, and no significant correlation was observed between RVEF and LVEF responses during exercise. The impairment of RVEF response to exercise seemed to be related to the proximal RCA stenosis. However, in the presence of multiple coronary vessel disease, increased RV afterload during exercise may also play a role in abnormal RVEF response in coronary artery disease. (author)