Prognostic properties of echocardiographic right ventricular outflow tract diameter in arrhythmogenic right ventricular cardiomyopathy

Abstract

Background/Introduction: Right ventricular outflow tract (RVOT) dilatation is a key phenotypic feature of arrhythmogenic right ventricular cardiomyopathy (ARVC). It is not known whether the echocardiographic RVOT diameter predicts adverse cardiovascular events. Purpose(s): This study aimed at investigating the utility of the RVOT diameter for predicting ventricular arrhythmia (VA) or death in ARVC. Material(s) and Method(s): This study included patients with genetic testing and fulfilling the revised 2010 Task Force Criteria for definite ARVC. Participants were recruited from three prospective ARVC registries and categorized according to a primary or secondary prevention situation. Outcome was defined as the first occurrence of VA or death. The RVOT PSAX diameter (Figure) was indexed to body surface area (BSA) and Cox regression models were used to evaluate its association with outcome. Result(s): 331 ARVC patients with mean age 47 (standard deviation (SD) 16.2) years, 73% in primary prevention, and median follow-up of 6.8 IQR 3.9-10.5] years were included. Mean RVOT/BSA diameter was 19.6 (4.1) mm/m2. Univariable regression revealed a strong association between RVOT/BSA and increased risk of VA (hazard ratio (HR) 1.07 95% confidence interval 1.02-1.13], p-value 0.003) or death (HR 1.33 1.24-1.42], p-value <0.001). Bivariable models demonstrated that the association with VA was independent of LVEF (HR 1.08 1.03-1.14], p-value 0.003), but not RV fractional area change (FAC; HR 1.02 0.96-1.08], p-value 0.506) or RV basal end-diastolic diameter (EDD; HR 1.03 0.97-1.10], p-value 0.355), while the association with death was independent of LVEF (HR 1.29 1.19-1.40], p-value <0.001), RVFAC (HR 1.19 1.09-1.29], p-value <0.001), and RVEDD (HR 1.27 1.13-1.42], p-value <0.001). In primary prevention, RVOT/BSA was marginally associated with VA (HR 1.07 1.00-1.16], p-value 0.050) and strongly with death (HR 1.34 1.22-1.47], p-value <0.001). In secondary prevention, RVOT/ BSA was not associated with VA (HR 1.00 0.93-1.07], p-value 0.968) but with death (HR 1.29 1.13-1.48], p-value <0.001). In the total ARVC population, the relationship between instantaneous risk of VA or death and RVOT diameter was non-linear and nearly exponential. Conclusion(s): Patients with definite ARVC and larger RVOT/BSA diameter are at increased risk of adverse events during follow-up. In patients with definite ARVC, RVOT/BSA diameter is useful for event prediction in both primary and secondary prevention.