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[Exercise-induced left bundle branch block in treadmill exercise test: clinical significance and prognosis]
T Aoki1, H Nishikawa, M Motoyasu
1Division of Cardiology, Yamada Red Cross Hospital.
Insights
Exercise induced left bundle branch block (LBBB) is rare and poorly understood. Patients with exercise induced LBBB require careful follow-up, as underlying cardiac conditions may not always be apparent.
Area of Science:
- Cardiology
- Electrophysiology
Background:
- Exercise-induced left bundle branch block (LBBB) is an uncommon finding during treadmill testing.
- Its clinical characteristics and long-term prognosis remain poorly understood, necessitating further investigation.
Observation:
- A review of 3,459 patients revealed exercise-induced LBBB in only 6 individuals (0.17%).
- Among these, 50% had known cardiac disease (coronary artery disease or dilated cardiomyopathy).
- Thallium-201 myocardial scintigraphy showed equivocal results for coronary artery disease in some patients.
Findings:
- Exercise-induced LBBB can occur in patients with and without significant coronary artery disease.
- One patient developed dilated cardiomyopathy during follow-up, highlighting the potential for developing cardiac conditions.
- Tl-201 scintigraphy may not be definitive in diagnosing coronary artery disease in this specific patient group.
Implications:
- Patients experiencing exercise-induced LBBB, particularly those without a clear underlying cardiac diagnosis, warrant meticulous clinical monitoring.
- Further research is needed to elucidate the mechanisms and optimize management strategies for exercise-induced LBBB.
- This study underscores the importance of comprehensive cardiac evaluation and long-term follow-up for individuals with this exercise-induced electrocardiographic abnormality.
Abstract:
Exercise induced left bundle branch block (LBBB) is poorly understood. We investigated its clinical characteristics and prognosis. The records of 3,459 consecutive patients who underwent treadmill exercise testing were reviewed. Exercise induced LBBB was identified in 6 patients (0.17%). Three out of six patients had underlying cardiac disease; two had coronary artery disease and one dilated cardiomyopathy. Three out of five had redistribution on Tl-201 myocardial scintigraphy. In one of these three patients, however, coronary angiography demonstrated no significant narrowings. Tl-201 myocardial scintigraphy in patients with exercise induced LBBB may be undetermined for coronary artery disease. During follow-up, one of six patients had depressed left ventricular function and was diagnosed as having dilated cardiomyopathy. It is thus obvious that exercise induced LBBB without a specific underlying heart disease should be followed up carefully.