Right-Sided Heart Wall Thickening and Delayed Enhancement Caused by Chronic Active Myocarditis Complicated by Sustained Monomorphic Ventricular Tachycardia
An asymptomatic healthy 65-year-old man was referred to a hospital for inverted T waves in the precordial leads (Figure 1) with paroxysmal advanced atrioventricular block in the ECG. Chest x-ray showed mild cardiac enlargement (Figure 2), and an echocardiogram showed right ventricular (RV) wall thickening (arrow in Figure 3). Five months later, the patient was referred to another hospital complaining of chest discomfort. Coronary angiogram was normal, but sustained monomorphic ventricular tachycardia (VT) occurred. Suffering from incessant VT, the patient was transferred to our hospital. The ECG and echocardiogram were almost the same as in previous studies. Enhanced multislice computed tomography revealed isolated right atrial, RV, and partial left ventricular (LV) wall thickening with extensive delayed enhancement (Figure 4) but no other organic diseases, which was confirmed by cardiac magnetic resonance (Figure 5).
In an electrophysiological study, 2 sustained monomorphic VTs (Figure 6) were induced, located in the RV midseptum by endocardial ventricular mapping. Radiofrequency ablation was performed at both sites; subsequently, neither VT could be induced. Because of the multislice computed tomography and cardiac magnetic resonance findings, endocardial biopsies were obtained from the RV (Figure 7) that showed interstitial edema, fibrosis, and myocyte destruction with a dense infiltrate of lymphocytes, suggesting chronic active myocarditis, which was consistent with his clinical course. Presumably, the thickening of the right atrial and RV free walls is related to lymphocytic infiltration and edema in the multislice computed tomography and cardiac magnetic resonance. A cardioverter-defibrillator was implanted, and the patient was given 40 mg/d prednisolone. He had no recurrent VTs after discharge.