Prognostic value of three-dimensional electroanatomic voltage mapping in patients with arrhythmias of right ventricular origin

Endocardial voltage mapping (EVM) by CARTO system offers the potential to accurately identify the presence, location and extent of right ventricular (RV) low-voltage regions (i.e. electroanatomic scars) which may represent the substrate of life-threatening right ventricular tachyarrhythmias. This study prospectively evaluated the prognostic value of RV electroanatomic scars in a cohort of patients presenting clinically with arrhythmias of RV origin. Methods The study population comprised 109 consecutive patients (73 men and 36 women; mean age 36±14 years) with a left bundle branch block pattern ventricular arrhythmia, of which 21 with ventricular tachycardia (VT), 64 with non sustained VT, frequent and/or repetitive premature ventricular beats were detectable in 24 patients. All patients underwent detailed clinical evaluation and high density RV EVM by sampling multiregional RV bipolar electrograms (197±23 sampled points) to identify RV electroanatomic scars (defined as low-amplitude areas with bipolar electrogram <0,5 mV). Results Electroanatomic scars were found in 54 patients (49%), affecting 20,4±13,0% (range 2,6% to 49,8%) of the RV free wall. The presence of electroanatomic scar significantly correlated with a positive family history (P<0,001), late potentials on SAECG (P<0,001), and RV dilatation/dysfunction (P<0,001). During the follow-up, mean period of 49±13 months, 25 of 109 patients (23%) experienced malignant arrhythmic events such as sudden death in 2, cardiac arrest due to ventricular fibrillation in 4, appropriate ICD intervention in 7, and unstable VT leading to syncope in 12. Unexplained syncope (P<0,001) and electroanatomic scar (P<0,001) were significantly associated with the arrhythmic events. Among patients with an abnormal RV EVM, those who experienced arrhythmic events during follow-up had a significantly greater percentage of electroanatomic scar (27,4±10,5% versus 16,0±12,3%, p<0,001). After adjustment for age, family history, VT, and RV dilatation/dysfunction, unexplained syncope (OR=15,9, 95%CI=4,1-61,8; P<0,001) and RV electroanatomic scars (OR=9,28, 95% CI=2,0-42,7; P=0,004) remained independent predictors of malignant arrhythmic outcome. Conclusions Electroanatomic scars were found in approximately half of patients with significant arrhythmias of right ventricular origin. There was a significant correlation between electroanatomic scar extent and incidence of arrhythmic events during follow-up. Electroanatomic scar, unlike RV dilatation/dysfunction, was an independent predictor of malignant arrhythmic outcome.