The aims of this study were: (1) to test whether first-pass radionuclide angiocardiography (FPRNA) adds useful information to perfusion scintigraphy; and (2) to assess the relative accuracy of perfusion and functional imaging in combination with dipyridamole for the evaluation of CAD.
Methods: Thirty patients with angiographically proven CAD (17 with prior infarction) were studied on separate days at rest and with dipyridamole infusion (0.7 mg/kg over 4 min). Tomographic images were evaluated using an uptake score. Dipyridamole FPRNA was considered positive in case of stress-induced wall motion abnormality or ejection fraction decrease.
Results: The CAD detection rate of perfusion imaging was 100%, while that of FPRNA was 70% using wall motion criteria, 63% using ejection fraction response and 77% considering any abnormality. For CAD localization, perfusion imaging showed 76% sensitivity, 96% specificity and 82% accuracy. FPRNA results were 50%, 100% and 60%, respectively. Perfusion imaging was significantly superior to FPRNA also excluding from the analysis the infarct-related vessels. FPRNA did not identify multivessel CAD, which was correctly detected by perfusion imaging in most cases. Both techniques were more sensitive in case of > or = 90% stenosis, but the difference was more remarkable for FPRNA (sensitivity 65% versus 14%, p < 0.0005).
Conclusions: Dipyridamole FPRNA did not add noteworthy clinical information to perfusion imaging regarding CAD detection and evaluation of disease extent. The main contribution of a positive FPRNA was its relation with coronary obstruction severity. These results confirm the superiority of perfusion over functional imaging in combination with coronary vasodilators.