Aim
To assess the additional prognostic significance of echocardiographic parameters of subpulmonary left ventricular (LV) size and function in patients with a systemic right ventricle (SRV).

Methods and Results
All adults with a SRV who underwent transthoracic echocardiography in 2010-2018 at a large tertiary center were identified. Biventricular size and function were assessed at the most recent exam. The study endpoint was all-cause mortality or heart/heart-lung transplantation.

We included 180 patients, 100(55.6%) male, mean age 42.4±12.3 years, of whom 103(57.2%) had undergone Mustard/Senning operations and 77(42.8%) had congenitally corrected transposition of great arteries.

Over 4.9[3.8-5.7] years, 28(15.6%) patients died and 4(2.2%) underwent heart or heart-lung transplantation. Univariable predictors of the study endpoint included age, NYHA functional class III or IV, history of atrial arrhythmias, presence of pacemaker or cardioverter-defibrillator, high BNP, and echocardiographic markers of SRV and subpulmonary LV size and function. On multivariable Cox analysis of echocardiographic variables, indexed LV end-systolic diameter (ESDi; HR 2.77 [95%CI 1.35-5.68], p=0.01), LV fractional area change (FAC; HR 0.7 [95%CI 0.57-0.85], p=0.002), SRV basal diameter (HR 1.66 [95%CI 1.21-2.29], p=0.005), and SRV FAC (HR 0.65 [95%CI 0.49-0.87], p=0.008) remained predictive of mortality or transplantation. On ROC analysis, subpulmonary LV parameters performed better than SRV markers in predicting adverse events.

Conclusions
SRV basal diameter, SRV FAC, LV ESDi, and LV FAC are significantly and independently associated with mortality and transplantation in adults with a SRV. Accurate echocardiographic assessment of both SRV and subpulmonary LV is therefore essential to inform risk stratification and management.