Abstract 416: Morpho-functional Correlates of the Electroanatomic Abnormalities in Arrhythmogenic Right Ventricular Cardiomyopathy
Background. The sensitivity and specificity of cardiac magnetic resonance (CMR) findings in the diagnosis of arrhythmogenic right ventricular cardiomyopathy (ARVC) are still debated. Low-voltage areas (LVA) on 3-dimensional electroanatomic voltage mapping (EAM) reliably identify diseased areas in the RV wall in these patients. We compared CMR and EAM findings to evaluate the diagnostic and pathophysiologic relevance of different CMR parameters for ARVC diagnosis.
Methods. Twenty-two consecutive patients (age 47±16 years, 11 males) with a diagnosis of ARVC according to current criteria, underwent gadolinium contrast-enhanced CMR and RV EAM. For comparisons with CMR findings, EAM was divided into 5 areas: outflow tract (OT), postero-inferior wall (PW), free wall (FW), apex (Ap), septal wall (SW). A LVA was defined as an area with a mean bipolar voltage < 1.5 mV.
Results. At CMR, RV global dysfunction was present in 6 (27%) patients and correlated with the extent of RV involvement at EAM, with patients showing >1 LVA having significantly lower RV ejection fraction compared to those without LVAs (50.5±4.5% vs 55.3±4%, respectively, P = 0.031). Regional RV wall-motion abnormalities were present in 14 (64%) patients and were localized in the OT in 5 (23%), in the PW in 9 (41%), in the FW in 6 (27%) and in the apex in 4 (18%). Regional wall-motion abnormalities correlated with the presence of LVA, with the most significant association being found with the OT (p <0.001). RV fat infiltration and RV delayed enhancement were reported in 8 (36%) and in 13 (59%) patients, respectively. Delayed enhancement was the CMR finding more significantly associated with the presence of LVA (P = 0.002 in the OT, P = 0.001 in the PW, and P = 0.006 in the FW). On the other hand, RV fat infiltration was correlated with LVA only if associated with regional wall-motion abnormalities.
Conclusions. The presence and distribution of RV delayed enhancement and regional wall-motion abnormalities are the CMR morpho-functional abnormalities more strongly associated with electroanatomic abnormalities. Fat infiltration without a concomitant regional dysfunction is not associated with electroanatomic abnormalities, thus being confirmed as the less reliable CMR diagnostic criterion for ARVC.