Three-dimensional electroanatomic voltage mapping increases accuracy of diagnosing arrhythmogenic right ventricular cardiomyopathy/dysplasia

Background - Three- dimensional electroanatomic voltage mapping offers the potential to identify low-voltage areas that correspond to regions of right ventricular (RV) myocardial loss and fibrofatty replacement in patients with arrhythmogenic RV cardiomyopathy/dysplasia (ARVC/D). Methods and Results - Thirty-one consecutive patients (22 men and 9 women; mean age, 30.8 +/- 7 years) who fulfilled the criteria of the Task Force of the European Society of Cardiology and International Society and Federation of Cardiology (ESC/ISFC) for ARVC/D diagnosis after noninvasive clinical evaluation underwent further invasive study including RV electroanatomic voltage mapping and endomyocardial biopsy (EMB) to validate the diagnosis. Multiple RV endocardial, bipolar electrograms (175 +/- 23) were sampled during sinus rhythm. Twenty patients (group A; 65%) had an abnormal RV electroanatomic voltage mapping showing >= 1 area (mean 2.25 +/- 0.7) with low- voltage values (bipolar electrogram amplitude < 0.5 mV), surrounded by a border zone (0.5 to 1.5 mV) that transitioned into normal myocardium (> 1.5 mV). Low-voltage electrograms appeared fractionated with significantly prolonged duration and delayed activation. In 11 patients (group B; 35%), electroanatomic voltage mapping was normal, with preserved electrogram voltage (4.4 +/- 0.7 mV) and duration (37.2 +/- 0.9 ms) throughout the RV. Low-voltage areas in patients from group A corresponded to echocardiographic/angiographic RV wall motion abnormalities and were significantly associated with myocyte loss and fibrofatty replacement at EMB (P < 0.0001) and familial ARVC/ D (P < 0.0001). Patients from group B had sporadic disease and histopathological evidence of inflammatory cardiomyopathy (P < 0.0001). During the time interval from onset of symptoms to the invasive study, 11 patients (55%) with electroanatomic low- voltage regions received an implantable cardioverter/defibrillator because of life-threatening ventricular arrhythmias, whereas all but 1 patient with a normal voltage map remained stable on antiarrhythmic drug therapy (P = 0.02). Conclusions - Three- dimensional electroanatomic voltage mapping enhanced accuracy for diagnosing ARVC/ D ( 1) by demonstrating low- voltage areas that were associated with fibrofatty myocardial replacement and (2) by identifying a subset of patients who fulfilled ESC/ISFC Task Force diagnostic criteria but showed a preserved electrogram voltage, an inflammatory cardiomyopathy mimicking ARVC/ D, and a better arrhythmic outcome.