Submaximal exercise testing plus atropine in myocardial perfusion SPECT.

Area of Science:

• Cardiology
• Nuclear Medicine
• Diagnostic Imaging

Background:

• Submaximal exercise testing is a common method for evaluating myocardial perfusion.
• Myocardial perfusion single-photon emission computed tomography (SPECT) is a key diagnostic tool.
• Atropine can be used to augment exercise stress in SPECT imaging.

Purpose of the Study:

• To assess the diagnostic utility of myocardial perfusion SPECT combined with intravenous atropine administration.
• To determine if atropine enhances the detection of ischemia during stress testing.

Main Methods:

• 172 patients underwent symptom-limited ergometric testing followed by SPECT with intravenous atropine.
• A subset of 23 patients with scintigraphic ischemia underwent a second SPECT without atropine.
• Summed difference scores (SDS) were used to quantify and compare ischemia severity.

Main Results:

• Atropine administration induced angina or ST-segment depression in 43.6% of patients.
• 35% of patients exhibited scintigraphic ischemia (SDS ≥2) only with atropine.
• SPECT imaging with atropine showed significantly greater ischemia (SDS 5.6 ± 4.5 vs. 3.1 ± 2.8; P=.0001).

Conclusions:

• Intravenous atropine significantly increases the diagnostic yield of SPECT myocardial perfusion imaging.
• A substantial proportion of patients with exercise-induced ischemia may be missed without atropine augmentation.
• Atropine-enhanced SPECT improves the identification of significant coronary artery disease.