Incremental Diagnostic Value of Right Atrial Strain in Arrhythmogenic Right Ventricular Cardiomyopathy: A Cardiac MRI Study

RATIONALE AND OBJECTIVES To evaluate the discriminative performance of right atrial (RA) phasic function in arrhythmogenic right ventricular cardiomyopathy (ARVC) patients with preserved right ventricular (RV) function. MATERIALS AND METHODS Right atrial and ventricular strain, together with conventional cardiac MRI (CMR) parameters, were assessed in 38 patients with ARVC and preserved RV function, 38 patients with ARVC and reduced RV function, and 38 healthy controls between January 2012 and May 2021. RESULTS Compared to controls, ARVC patients with preserved RV function showed impaired RA reservoir and conduit strain, as well as reduced RA passive emptying fraction, despite normal RA size. RA conduit strain <17% showed discriminative performance for identifying ARVC with preserved RV function (AUC = 0.79). The combination of RA conduit strain and RV global longitudinal strain (RVGLS) further improved discriminative performance (AUC = 0.89, P < 0.001). Multivariable logistic regression identified RA conduit strain (OR = 0.88, P = 0.005) and RVGLS (OR = 1.37, P < 0.001) as independently associated factors. In addition, RA conduit strain impairment showed modest incremental diagnostic value beyond RVGLS (χ² increased from 31.6 to 41.3, P = 0.002) and correlated with more advanced RV dysfunction and higher N-terminal pro-brain natriuretic peptide (NT-proBNP) levels across the overall ARVC cohort. CONCLUSION RA phasic strain is impaired in ARVC even when RV function is preserved. In combination with RVGLS, RA conduit strain showed improved diagnostic performance and may serve as a potential adjunctive imaging marker, although further evaluation is required.