Intravenous dipyridamole thallium-201 SPECT imaging in patients with left bundle branch block

Area of Science:

• Cardiology
• Nuclear Medicine
• Diagnostic Imaging

Background:

• Exercise Thallium-201 (Tl-201) imaging is often indeterminate for left anterior descending (LAD) coronary artery stenosis in patients with left bundle branch block (LBBB).
• This indeterminacy stems from frequent septal perfusion defects with redistribution, irrespective of actual LAD stenosis.

Purpose of the Study:

• To evaluate the utility of dipyridamole Tl-201 SPECT in diagnosing LAD coronary artery stenosis in patients with LBBB.
• To compare the diagnostic accuracy of dipyridamole Tl-201 SPECT versus exercise Tl-201 imaging for LAD stenosis in LBBB patients.

Main Methods:

• Nineteen patients with LBBB underwent dipyridamole Tl-201 SPECT.
• Coronary angiography was performed in select patients with abnormal findings or clinical suspicion.
• Follow-up was conducted to assess for clinical coronary artery disease.

Main Results:

• Fourteen out of nineteen patients with LBBB showed normal dipyridamole Tl-201 SPECT findings.
• Of 11 patients with normal dipyridamole Tl-201 SPECT and no coronary angiography, none developed clinical coronary artery disease during follow-up.
• One patient with significant LAD stenosis had abnormal septal perfusion on dipyridamole Tl-201 SPECT.

Conclusions:

• Dipyridamole Tl-201 SPECT may be a more reliable non-invasive tool for excluding LAD stenosis in patients with LBBB compared to exercise Tl-201 imaging.
• Normal dipyridamole Tl-201 SPECT results in LBBB patients appear to exclude significant LAD stenosis effectively.