Relationship between electrical and morphologic alterations of the right ventricle in arrhythmogenic right...

In arrhythmogenic right ventricular cardiomyopathy (ARVC), the relationship between structural and electrical abnormalities remains unclear.

This study aimed to assess the spatial association between low-voltage areas (LVAs) and morphofunctional abnormalities.

We retrospectively analyzed patients with definite ARVC who underwent computed tomography imaging and endocardial/epicardial ventricular tachycardia ablation. The right ventricle was divided into 7 regions, and morphofunctional abnormalities were classified as static or kinetic. LVAs were defined as bipolar voltage of <0.5 mV over ≥5 contiguous points.

Thirty-four patients with definite ARVC (mean age 42 ± 14 years; 82% male) were included. Epicardial LVAs were more common in segments with static (64%) or kinetic abnormalities (68%) than normal ones (39%; P < .01) but were still present in 95%-96% of morphologically normal segments. Half of the epicardial segments with LVAs had no static or kinetic abnormality, and correlation with morphology was poor (kappa [κ] ≈ 0.04-0.05). Endocardial LVAs were more frequent with static (15%) and kinetic abnormalities (16%) (P < .02), yet more than half of morphologically normal segments had endocardial scars, with weak correlation (κ < 0.25). Transmural LVAs were found in abnormal segments but remained uncommon overall, and spatial concordance was poor (κ < 0.10). Transmural fat correlated with endocardial LVAs (12% vs 1%; P = .016) but poorly with epicardial LVAs (κ < 0.39). Notably, 33% of ventricular tachycardia isthmus segments lacked any morphofunctional abnormality.

In ARVC, arrhythmogenic substrates frequently exist without overt morphologic changes. Electrophysiological studies provide additional diagnostic value, supporting its integration into diagnostic criteria.