"Cardiac sarcoidosis masquerades as genetic cardiomyopathy": ARVD "doppelganger

Omotoye et al have described a rare case in the latest edition of JACC Case reports, where a middle-aged man presented with a perfect phenocopy of arrhythmogenic right ventricular dysplasia (ARVD) and was treated for the same. But subsequent treatment refractory ventricular tachycardia (VT) episodes led to further investigations which identified the underlying cause to be cardiac sarcoidosis.

This case highlights the close overlap of presentation and investigational findings between ARVD and sarcoidosis and suggests high index of suspicion when encountering such a clinical dilemma.

A 54 year old male was evaluated for progressive dyspnea. ECG suggested epsilon waves in precordial leads with T inversion in V1-V3. Subsequent electrocardiograms revealed salvos of ventricular tachycardia (VT) and premature ventricular complex left bundle branch block configuration and very delayed precordial R-wave transition.

Echocardiography showed severe biventricular systolic dysfunction with a left ventricular ejection fraction of 15% to 20% and a severely dilated right ventricle. Coronary angiography showed moderate single-vessel disease without significant occlusion that would require coronary intervention.

Cardiac magnetic resonance imaging revealed biventricular systolic dysfunction with right ventricular dilatation and delayed hyperenhancement of gadolinium in the basal to mid septum of the right and left ventricles, extending to the epicardial left ventricular inferior wall. These imaging findings as well as electrocardiographic findings were initially suggestive of ARVC or left ventricular cardiomyopathy.

Because of salvos of VT and frequent premature ventricular complexes, amiodarone was commenced, along with goal-directed medical therapy for heart failure and biventricular systolic dysfunction, and a dual-chamber implantable cardioverter-defibrillator was implanted for secondary prevention.

It was notable that genetic testing did not reveal any known abnormal loci associated with ARVD. Whole-body 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET) was performed and showed nonspecific focal abnormal uptake in the visceral organs without radiographic correlate.

Cardiac FDG PET showed some scattered increased FDG uptake in the area of resting ammonia perfusion defect at the inferior-apical segments and basal inferior-septal segments, suggestive of active inflammation and scar in the same location. No specific disorder could be diagnosed with these findings.

The patient subsequently developed recurrent and intractable ventricular arrhythmias after discharge from initial hospitalization, which prompted combined endocardial-epicardial VT ablation of 2 clinical VTs, with one originating from the anterolateral right ventricle extending from base to apex and the other localized to the basal inferolateral right ventricle.

Four weeks after the initial VT ablation, the patient presented in electrical storm, with multiple device therapies and implantable cardioverter-defibrillator shocks that culminated in significant anxiety. He then underwent surgical left cardiac sympathetic denervation (left stellate ganglionectomy) for better control of his ventricular arrhythmias. Lung biopsy and lymph node biopsy were performed during this surgery, which revealed histologically normal lung and discrete lymph node granulomata, respectively.

Thus, biopsy finally clenched the diagnosis of cardiac sarcoidosis (CS) and the patient was commenced on immunosuppressive therapy for CS with an initial good response. However, he had recurrent arrhythmias and worsening decompensated heart failure. He was successfully enlisted for cardiac transplantation and underwent successful transplantation with remarkable recovery and return of his quality of life.

The authors share following insights from this rare case:

1. CS and ARVD can share an overlapping phenotype.

2. The finding of epsilon waves on electrocardiography is characteristic of ARVC but not pathognomonic of ARVC, as this phenomenon can be seen in other cardiomyopathies, such as CS.

3. Although the presence of AV block and other electrocardiographic evidence of His-Purkinje system disease helps rule in CS, the absence of such conduction abnormalities does not necessarily rule it out.

4. Although FDG PET and other imaging modalities provide important information about disease activity, the presence of a biopsy-proven diagnosis of sarcoidosis remains a useful correlation to differentiate it from ARVC.

Source: JACC case reports: DOI: 10.1016/j.jaccas.2021.04.017