Related Experiment Videos
Intravenous dipyridamole thallium-201 SPECT imaging in patients with left bundle branch block
J F Rockett1, W C Wood, M Moinuddin
1Department of Radiology, Baptist Memorial Hospital, Memphis, Tennessee 38119.
Insights
Dipyridamole Thallium-201 SPECT (Tl-201) shows promise for excluding left anterior descending (LAD) coronary artery stenosis in patients with left bundle branch block (LBBB). This method appears more reliable than exercise Tl-201 imaging for this specific patient group.
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.
Abstract:
Tl-201 exercise imaging in patients with left bundle branch block (LBBB) has proven to be indeterminate for significant left anterior descending (LAD) coronary artery stenosis because of the presence of immediate septal perfusion defects with redistribution on delayed images in almost all cases. Tl-201 redistribution occurs regardless of the presence or absence of LAD stenosis. Nineteen patients having LBBB were evaluated with dipyridamole Tl-201 SPECT. Fourteen of these subjects had normal dipyridamole Tl-201 SPECT imaging. Three patients had normal coronary angiograms. None of the remaining 11 patients with normal dipyridamole Tl-201 SPECT images was found to have clinical coronary artery disease in a 5-11 month follow-up period. Five patients had abnormal septal perfusion. Four underwent coronary angiography. One had a significant LAD stenosis. The single patient with septal redistribution who refused to undergo coronary angiography died shortly thereafter of clinical coronary artery disease. This preliminary work suggests that dipyridamole Tl-201 SPECT may be more useful for excluding LAD stenosis in patients with LBBB than Tl-201 exercise imaging.