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A repeat ECG (Figure 1b) showed low-atrial rhythm, with complete right bundle branch block and repolarisation abnormalities in the inferior leads. On examination, heart sounds were normal, his lung fields were clear, the jugular venous pressure was not elevated and there was no peripheral oedema.
A 2D echocardiogram (Figure 2) demonstrated asymmetric left ventricular septal hypertrophy, with a maximum wall thickness of 22 mm at the septum, normal left ventricular cavity dimensions and normal ejection fraction. Diastolic function was impaired with a delayed relaxation filling pattern. No systolic anterior movement of the mitral valve or left ventricular outflow tract obstruction was observed.
He underwent an exercise test, which showed a poor heart rate response (54 % of his predicted maximum), normal blood pressure response and no arrhythmias or ST-segment changes. Holter monitoring demonstrated an average heart rate of 61 bpm (46-98 bpm) and no non-sustained ventricular tachycardia.
During an episode of dizziness, the ECG showed junctional rhythm with retrograde-conducted P waves (Figure 3). A diagnosis of hypertrophic cardiomyopathy and sinus node dysfunction was made and a dual chamber rate-responsive pacemaker was implanted, with considerable improvement in patient’s exercise capacity and resolution of his dizzy episodes. No medical treatment was given. He had no family history of sudden death or cardiomyopathy. Family screening was advised.
Three months later, he was admitted to the Emergency Department complaining of extreme fatigue and pre-syncope. He was found to have a rapid, low volume pulse and was hypotensive. The electrocardiogram revealed a broad complex tachycardia with a rate exceeding 200 beats per minute (Figure 4). The morphology was suggestive of ventricular tachycardia (VT) originating from the postero-apical left ventricle. DC cardioversion successfully restored sinus rhythm. Electrolytes and cardiac enzymes were normal. Echocardiographic features were unchanged. The pacemaker was upgraded to an ICD.
The presence of rapidly progressive electrocardiographic changes (from incomplete to complete right bundle branch block) and sinus node dysfunction, together with the occurrence of haemodynamically unstable VT in a patient considered at low risk for arrhythmic events, are atypical features of HCM caused by sarcomeric protein disease. For this reason, an endomyocardial biopsy was performed. The histology showed a mature non-caseating granuloma in the subendocardium, suggestive of cardiac sarcoidosis. A CT scan of the chest showed a single lymph node >1 cm in the right paratracheal region and another smaller lymph node beneath the tracheal bifurcation. Therapy with prednisolone and amiodarone was initiated.
Over the next five months, the patient experienced 28 appropriate ICD therapies (either ATP or DC shock) for recurrent sustained VT associated with impairment of consciousness. Bisoprolol, mexiletine and hydroxychloroquine were added to his therapy, but arrhythmic control proved difficult to achieve, necessitating an electrophysiological study. Seven monomorphic VTs were induced and ablated. The patient has since remained free from symptoms of arrhythmia and ICD interventions. A follow-up 2D echocardiogram showed normal left ventricular cavity dimensions, mildly impaired systolic function, thinning and dyskinetic movement of the basal septum, and mild right ventricular dilation with normal ejection fraction and normal estimated pulmonary artery systolic pressure (Figure 1). Therefore immunosuppressive treatment resulted in resolution of the “hypertrophy” (which was probably caused by infiltration and oedema), but did not prevent the frequent VT following ICD implantation.
By Dr Perry Elliott, The Heart Hospital, University College, London, United Kingdom
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