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[Myocardial perfusion in patients with left bundle branch block and without coronary artery disease]
M Narita1, T Kurihara, K Murano
1Department of Internal Medicine, Sumitomo Hospital.
Insights
Left bundle branch block (LBBB) can cause myocardial perfusion abnormalities. Exercise stress thallium-201 tomography revealed distinct diffuse and focal perfusion defects in LBBB patients, differing from coronary artery disease patterns.
Area of Science:
- Cardiology
- Nuclear Medicine
- Diagnostic Imaging
Background:
- Left bundle branch block (LBBB) can affect myocardial perfusion assessment.
- Distinguishing LBBB-induced perfusion changes from coronary artery disease (CAD) is clinically important.
Purpose of the Study:
- To evaluate myocardial perfusion in patients with LBBB using exercise stress (Ex)-redistribution (RD) myocardial tomography with thallium-201 (201Tl).
- To compare perfusion abnormalities in LBBB patients with those in CAD patients.
Main Methods:
- 23 patients with LBBB and 9 patients with CAD underwent 201Tl Ex-RD myocardial tomography.
- Bull'-eye maps were generated to assess 201Tl distribution and washout rate (WOR).
Main Results:
- 65% of LBBB patients showed perfusion abnormalities, categorized as diffuse (67%) or focal (33%).
- Focal defects were associated with comorbidities like hypertension or aortic stenosis.
- Diffuse defects showed less apical involvement and milder septal defects compared to CAD.
Conclusions:
- LBBB can induce distinct myocardial perfusion abnormalities.
- The patterns of perfusion defects in LBBB differ from those seen in CAD, particularly regarding apical and septal involvement.
- Further investigation into the mechanisms underlying LBBB-induced perfusion defects is warranted.
Abstract:
For the evaluation of myocardial perfusion in patients with left bundle branch block (LBBB), we performed exercise stress (Ex)-redistribution (RD) myocardial tomography with thallium-201 (201Tl) in 23 patients with LBBB and without coronary artery disease (CAD). Myocardial images in patients with LBBB were compared with those of 9 patients with CAD who showed Ex induced transient septal defect. Bull'-eye maps (201Tl distribution maps at Ex and RD and 201Tl washout rate [WOR] map) were made from myocardial tomograms. In 23 patients with LBBB, 15 patients (65%) developed myocardial perfusion abnormality. In 10 (67%) of these 15 patients, transient perfusion defect appeared in the entire septum (diffuse type). On the other hand in 5 patients (33%), localized fixed perfusion defect developed at the boundary between septum and anterior wall (focal type). In focal type, every patient had other disease such as hypertension, aortic stenosis or sick sinus syndrome. While in patients with diffuse type, other diseases were observed in 30% (p less than 0.05) and they were limited to hypertension or diabetes mellitus. These facts suggested that mechanisms of perfusion abnormalities might be different between these two groups. We compared the perfusion abnormality between LBBB diffuse type and CAD. The extent of the defects was not different between two groups. Although apex was included within the defect in 89% of CAD population, apical defect was observed in only 20% of diffuse type (p less than 0.05). Minimal 201Tl WOR and 201Tl uptake ratio of septum to lateral wall indicated that exercise induced septal defect was slighter in diffuse type than CAD.(ABSTRACT TRUNCATED AT 250 WORDS)