Electroanatomic mapping of arrhythmogenic right ventricular dysplasia

OBJECTIVES We tested the hypothesis that spatial association of low-amplitu de intracardiac electrograms can identify the presence, location and extent of dyplastic regions in arrhythmogenic right ventricular dysplasia (ARVD). BACKGROUND Arrhythmogenic right ventricular dysplasia is a right ventricula r (RV) cardiomyopathy characterized pathologically by fibrofatty infiltrati on and clinically, by, a spectrum of arrhythmias, sudden cardiac death and RV failure. Diagnosis of ARVD still remains a clinical challenge. METHODS A three-dimensional electroanatomic mapping technique was used to m ap the RV of two groups of patients: 1) those with ARVD presenting with typ ical clinical, electrocardiographic and echocardiographic or magnetic reson ance imaging (MRI) findings; and 2) those with structurally, normal ventric les. RESULTS The dysfunctional RV area could be identified only in the first gro up and was characterized by the presence of discrete areas of abnormally lo w-amplitude electrograms. Hence, the normal voltage values observed in the control group (unipolar: 11.9 +/- 0.3 mV; bipolar: 4.6 +/- 0.2 mV [mean +/- SEM]) and in the nonaffected zones in the ARVD group (unipolar: 10.4 +/- 0 .2 mV; bipolar 4.6 +/- 0.2 mV) were reduced significantly (p < 0.05) in the dysplastic areas (unipolar: 3.3 +/- 0.1 mV; bipolar: 0.5 +/- 0.1 mV). The pathologic process mainly involved the RV anterolateral free wall, apex and inflow and outflow tracts and ranged from patchy areas to uniform and exte nsive involvement. Concordance between electroanatomic findings and MRI or echo cardiographic findings was noted in all patients. CONCLUSIONS The pathologic substrate in ARVD can be identified by spatial a ssociation of low-amplitude endocardial electrograms, reflecting replaced m yocardial tissue. The ability to accurately identify the presence, location and extent of the pathologic substrate may have important diagnostic, prog nostic and therapeutic implications. (J Am Coll Cardiol 2001;38:2020-7) (C) 2001 by the American College of Cardiology.