EFFECT OF AN ADDITIONAL ATROPINE INJECTION DURING DOBUTAMINE INFUSIONFOR MYOCARDIAL SPET

The aim of this study was to examine the value of an additional atropi ne injection in patients who do not achieve an adequate heart rate dur ing dobutamine infusion for myocardial perfusion SPET (single photon e mission tomography). Patients undergoing dobutamine myocardial SPET wh o failed to achieve greater than or equal to 85% of their age-predicte d maximal heart rate at the end of dobutamine infusion (D protocol) ha d a second dobutamine myocardial SPET study on a separate day with the addition of an atropine injection during the dobutamine infusion (D A protocol). Twenty-nine patients were studied. Tl-201 was used in 27 patients and Tc-99(m)-MIBI in two patients. All patients underwent co ronary angiography and significant coronary artery disease was found i n 19 of 29 patients. The mean heart rate obtained at the peak of dobut amine infusion in the D+A protocol was significantly higher than that in the D protocol (153.8 +/- 13.8 vs 117.5 +/- 15.3 beats min(-1)). Th e D + A protocol resulted in a higher diagnostic sensitivity for the d etection of stenosed coronaries compared with the D protocol (87 vs 80 %, P > 0.05) without changing the specificity (89% for both protocols) . On the other hand, the frequency of side-effects and ECG changes dur ing the D + A protocol was higher than that with the D protocol (32 vs 47). In conclusion, the addition of an atropine injection during dobu tamine infusion resulted in a higher diagnostic sensitivity for identi fying stenosed coronaries compared to dobutamine alone.