A CASE OF DILATED CARDIOMYOPATHY MANIFESTED BY EXERCISE-INDUCED LEFT-BUNDLE-BRANCH BLOCK

We report an extremely rare case of dilated cardiomyopathy manifested by exercise-induced left bundle branch block. A 63-year-old female cam e to our hospital because supraventricular arrhythmia had been detecte d at a check-up. A treatmill exercise test induced left bundle branch block. However, chest X-ray and echocardiography revealed no abnormal finding. Two years later, the patient experienced exertional dyspnea. A chest X-ray examination showed cardiomegaly, and echocardiography sh owed a moderate impairment of left ventricular function with left vent ricular dilatation. The diagnosis of dilated cardiomyopathy was made b y left ventricular myocardial biopsy. No previous cases have initially shown exercise-induced left bundle branch block which was followed by left ventricular dysfunction due to dilated cardiomyopathy. Careful l ong-term observation of the clinical course is necessary in patients w ith exercise-induced left bundle branch block which shows no significa nt underlying disease.