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Effect of an additional atropine injection during dobutamine infusion for myocardial SPET
1Department of Nuclear Medicine, Hacettepe University Medical Faculty, Ankara, Turkey.
Insights
Adding atropine during dobutamine stress testing improves heart rate response and diagnostic sensitivity for detecting coronary artery disease in myocardial perfusion SPECT. This enhanced protocol aids in identifying stenosed coronaries more effectively.
Area of Science:
- Nuclear Medicine
- Cardiology
- Diagnostic Imaging
Background:
- Myocardial perfusion single-photon emission tomography (SPET) is crucial for diagnosing coronary artery disease.
- Achieving an adequate heart rate during dobutamine infusion is essential for accurate SPET interpretation.
- Some patients fail to reach target heart rates with dobutamine alone, potentially limiting diagnostic accuracy.
Purpose of the Study:
- To evaluate the effectiveness of adding atropine to dobutamine infusion for myocardial perfusion SPET.
- To determine if this combined protocol improves diagnostic sensitivity for detecting coronary artery disease.
- To assess changes in heart rate, specificity, and side effects.
Main Methods:
- A comparative study involving 29 patients who underwent two dobutamine SPET protocols: dobutamine alone (D) and dobutamine with atropine (D + A).
- Patients who did not achieve 85% of their age-predicted maximal heart rate on the D protocol proceeded to the D + A protocol on a separate day.
- Coronary angiography was performed to confirm findings.
Main Results:
- The D + A protocol achieved a significantly higher peak heart rate (153.8 bpm) compared to the D protocol (117.5 bpm).
- Diagnostic sensitivity for detecting stenosed coronaries was higher with D + A (87%) versus D (80%), though not statistically significant (P > 0.05).
- Specificity remained unchanged (89%) for both protocols, but side effects and ECG changes were more frequent with D + A.
Conclusions:
- The addition of atropine to dobutamine infusion enhances heart rate response during myocardial perfusion SPET.
- The D + A protocol demonstrates a trend towards higher diagnostic sensitivity for identifying stenosed coronaries.
- While effective in augmenting heart rate, the D + A protocol is associated with an increased incidence of side effects.
Abstract:
The aim of this study was to examine the value of an additional atropine injection in patients who do not achieve an adequate heart rate during dobutamine infusion for myocardial perfusion SPET (single photon emission tomography). Patients undergoing dobutamine myocardial SPET who failed to achieve > or = 85% of their age-predicted maximal heart rate at the end of dobutamine infusion (D protocol) had 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. 201Tl was used in 27 patients and 99Tc(m)-MIBI in two patients. All patients underwent coronary angiography and significant coronary artery disease was found in 19 of 29 patients. The mean heart rate obtained at the peak of dobutamine 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]). The D + A protocol resulted in a higher diagnostic sensitivity for the detection 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 during the D + A protocol was higher than that with the D protocol (32 vs 47). In conclusion, the addition of an atropine injection during dobutamine infusion resulted in a higher diagnostic sensitivity for identifying stenosed coronaries compared to dobutamine alone.