Three-dimensional electroanatomical voltage mapping and histologic evaluation of myocardial substrate in right ventricular outflow tract tachycardia.

Objectives We tested whether 3-dimensional electroanatomical voltage mapping (EVM) may help in the differential diagnosis between idiopathic right ventricular outflow tract (RVOT) tachycardia and arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D). Background Right ventricular EVM has been demonstrated to reliably identify low-voltage regions (“electroanatomical scar”), which in patients with ARVC/D correspond to areas of fibrofatty myocardial replacement. Methods The study population comprised 27 patients (15 men and 12 women, age 33.9 ± 8 years) with RVOT tachycardia and no echocardiographic/angiographic evidence of right ventricular (RV) dilation/dysfunction, who underwent EVM and endomyocardial biopsy (EMB) for characterization of ventricular tachycardia (VT) substrate before catheter ablation. Results Electroanatomical voltage mapping was normal in 20 of 27 patients (74%, group A), with electrogram voltage >1.5 mV throughout the RV. The other 7 patients (26%, group B) showed ≥1 (1.4 ± 07) RV electroanatomical scar area(s) (bipolar voltage Conclusions An early/minor form of ARVC/D may mimic idiopathic RVOT tachycardia. Electroanatomical voltage mapping is able to identify RVOT tachycardia due to concealed ARVC/D by detecting RVOT electroanatomical scars that correlate with fibrofatty myocardial replacement at EMB and predispose to sudden arrhythmic death.