Effect of a Systemic Right Ventricle With a Biventricular Circulation on Cardiorespiratory Fitness

Adults with transposition of the great arteries and a systemic right ventricle (sRV) generally have lower cardiorespiratory fitness (CRF) than healthy adults with a systemic left ventricle (sLV). However, studies to date have not accounted for systolic function of the systemic ventricle. The objective was to assess and compare CRF in adults with an sRV vs sLV matched for clinical characteristics and systemic ventricular function.

A retrospective cross-sectional analysis was conducted on 24 adults with an sRV and 24 adults with an sLV matched for sex (20 males), age, body mass index, ejection fraction of the systemic ventricle (dysfunction in 23 pairs), New York Heart Association functional class (class II-III in 18 pairs), and doses of diuretics. Peak oxygen consumption ( $\dot{V}{O}_{2_{\text{peak}}}$ ) was compared with a Wilcoxon signed-rank test. The percentage of predicted $\dot{V}{O}_{2_{\text{peak}}}$ (% $\dot{V}{O}_{2_{\text{peak}}}$ ) and ventilation/carbon dioxide production slope ( ${\dot{V}}_E/{\dot{V}}_{{\text{CO}}_2}$ slope) were presented as secondary outcomes. Statistical significance was set at P < 0.05.

The population is characterized by high previous heart failure-related hospitalizations (22% in sRV and 58% in sLV) and diagnoses of pulmonary hypertension (61% in sRV and 60% in sLV). $\dot{V}{O}_{2_{\text{peak}}}$ did not differ between groups, with a mean difference (sRV - sLV) of 0.17 mL/kg/min (95% confidence interval [CI]: -2.74, 2.39; P = 0.770). The mean difference between groups for $\%\dot{V}{O}_{2_{\text{peak}}}$ was 5% (95% CI: -13, 2), and for ${\dot{V}}_E/{\dot{V}}_{{\text{CO}}_2}$ slope it was 0.92 (95% CI: -3.98, 2.14).

No differences in CRF were observed between adults with an sRV and an sLV when matched for clinical characteristics and systemic ventricular function.