Arrhythmogenic Right Ventricular Cardiomyopathy with Ventricular Tachycardia of Right Bundle Branch Block Morphology

Background: Ventricular tachycardia (VT) with right bundle branch block (RBBB) morphology suggesting left-sided involvement is rarely seen in arrhythmogenic right ventricular cardiomyopathy (ARVC).

Aims: To describe 2 ARVC cases presenting with RBBB-like VT morphology.

Methods and Results: We reviewed the cases of all ARVC patients who underwent diagnostic electrophysiologic testing or catheter ablation of VT in our hospital during the past 30 years. Of 18 patients 2 presented with RBBB-like VT.

The first male patient initially presented with left bundle branch block (LBBB)-superior axis VT at the age of 43 years. Baseline sinus ECG and MRI did not show findings suggestive of ARVC. The final diagnosis was made 10 years later when he presented with sustained VT having an RBBB morphology. Repeat MRI was now consistent with ARVC involving the RV only. Of note, genetic analysis did not identify any disease-causing or uncertain variants of ARVC.

The second male patient presented with sustained monomorphic RBBB-VT at age of 68 years. MRI demonstrated mostly LV involvement including thinning of the anterior and antero-lateral wall with akinesia from the level of the base to the apex as well as sub-endocardial and transmural late gadolinium enhancement. The RV was shown to have normal systolic function with suspected mild dyskinesia at the outflow tract area and few micro-aneurysms at the free wall. ARVC was suspected due to a positive family history. Actually, his brother was diagnosed several years earlier with ARVC at the age of 74 years old based on combination of sustained LBBB-VT and typical ARVC signs on MRI. Genetic testing revealed a disease-causing variant in the PKP2 gene (typical for ARVC) in both brothers.

Conclusions: ARVC should be considered in the differential diagnosis of RBBB-VT even in the elderly. A family history of VT with LBBB morphology may be helpful in the diagnosis. A patient with ARVC may exhibit both LBBB and RBBB-VT morphologies. Two brothers with ARVC may exhibit VT of different BB morphology.