Abstract 2827: Scar-Independent Ventricular Delayed Activation Areas: A New Substrate Marker of Arrhythmic Risk in ARVC
Background. Fibro-fatty tissue and cell-to-cell coupling abnormalities slow and fragment the wave of electrical depolarization in patients with arrhythmogenic right ventricular cardiomyopathy (ARVC), thus causing the presence of ventricular areas with delayed activation. We assessed the presence, distribution and clinical relevance of right ventricular delayed activation areas (DAAs) in a consecutive series of ARVC patients.
Methods. Fifteen consecutive patients (age 51±15 years, 8 men) with a biopsy-proven diagnosis of ARVC underwent right ventricular 3-dimensional electroanatomic mapping. A DAA was defined as an area >1 cm2 including at least 3 adjacent points with discrete bipolar potentials (>0.5 mV) occurring >10 ms after the end of the QRS. All patients received an ICD for primary prevention of sudden cardiac death.
Results. Multiple bipolar electrograms (155±36) during sinus rhythm were sampled in the RV. All patients had abnormal electroanatomic mapping (“scar”), showing >1 area with low-voltage values (bipolar electrogram amplitude <0.5 mV). DAAs were present in 13 (80%) patients. Two patterns of DAAs were identified; scar-dependent (6 pts), with DAAs located at or close to the border zone of the scar, and scar-independent DAAs (7 pts), located far outside from the scar tissue, in a zone of normal bipolar voltages. During 16±9 months of follow-up, 5 (33%) patients received appropriate ICD therapy for VT/VF. Scar-independent DAAs were significantly more prevalent in patients with, compared to those without, appropriate ICD therapy (100% vs. 20%, p=0.007), and significantly predicted appropriate ICD interventions at follow-up (Chi-Square=7.9, p=0.005).
Conclusions. Ventricular areas with delayed activation in ARVC display two different patterns. Scar-independent DAAs, possibly reflecting cell-to-cell coupling abnormalities, may represent a novel arrhythmic risk marker in patients with ARVC and warrant further investigation.