Abstract Introduction and aims Right ventricular (RV) dilation and dysfunction significantly impact the prognosis of dilated cardiomyopathy (DCM) patients, and early detection of subclinical changes is mandatory. Furthermore, right atrial (RA) size and function are still often neglected in DCM patients. Accordingly, our aims were to evaluate (i) right heart chambers and tricuspid annulus (TA) subclinical remodeling, and (ii) the prognostic value of RA compared to left atrial (LA) size and function in patients with DCM without clinical RV involvement, RV pressure/volume overload or sustained atrial tachyarrhythmias by advanced echocardiography techniques. Materials and methods Sixty-eight patients out of a cohort of 106 patients with DCM (mean age 60 years, 35 men) were evaluated by comprehensive transthoracic two- (2DE) and three-dimensional (3DE) and speckle-tracking (2DSTE) echocardiography, were compared to 62 age- and sex-matched healthy controls (mean age 61 years, 32 men), and were followed-up for 37 ± 16.6 months. Results DCM patients have RV and RA global longitudinal dysfunction by 2DSTE, and higher RA minimum volumes (Vmin) and TA areas despite having normal RV volumes and ejection fraction (EF) and RA maximum volumes (Vmax) by 3DE compared to controls (Table). RA and RV strain correlate with each other (r=0.360, p=0.013 for RA reservoir and r=0.347, p=0.017 for conduit strain). TA area correlates with RA contractile strain (r=-.293, p=0.046) and RV free-wall strain (r=0.373, p=0.008), RA Vmax (r=0.513, p<0.001), RV (r=0.404, p=0.004 for end-diastolic and r=0.444, p=0.001 for end-systolic) and left ventricular (LV) volumes (r=0.394, p=0.016) and LV EF (r=-.361, p=0.028). RA reservoir strain (AUC=0.769) has higher value for outcome prediction compared to LA strain (p=0.02 between them). Conclusion Patients with DCM have RV longitudinal dysfunction and decreased RA function, in the absence of clinical RV involvement or atrial arrhythmias, and decreased RA strain is associated with an increased risk of hospitalization and cardiac death.Comparison of right heart parametersPrognostic value of atrial function