(CCSP024) ISOLATING THE EFFECT OF A SYSTEMIC RIGHT VENTRICLE WITH BI-VENTRICULAR CIRCULATION ON CARDIORESPIRATORY FITNESS

Background: The clinical care of adults with a systemic right ventricle with biventricular circulation (sRV-biV) is, in part, guided by cardiorespiratory fitness (CRF) evaluation. A problem lies in the fact that prognosis is informed by values derived from adults with a systemic left ventricle (sLV). Some studies show that CRF is lower in adults with sRV-biV compared to those with a sLV. However, no studies have matched individuals for key clinical characteristics and ventricular function of the systemic ventricle.

METHODS AND RESULTS: We performed a retrospective comparison of exercise stress test results between 24 adults with sRV-biV and 24 adults with a sLV that were paired for sex, age, body mass index, ejection fraction of the systemic ventricle, NYHA class, and diuretics dose (Table 1). CRF (peak oxygen consumption [VO2]) was compared between groups with unpaired sample T-tests. Effect sizes are reported as Cohen’s d coefficient.

Peak VO2 did not differ between groups (sRV-biV: 20.3 ± 4.2 vs. sLV: 20.9 ± 6.0 mL/kg/min, p=0.57, d=0.15). Interestingly, when patients were dichotomized according to the Weber criterion for optimal CRF (sLV peak VO2 > or ≤ 20 mL/kg/min), peak VO2 was lower in sRV-biV in those with optimal CRF (sRV-biV: 21.0 ± 4.8 vs. sLV: 26.6 ± 5.1 mL/kg/min, p=0.03, d=1.01). In contrast, peak VO2 was greater in sRV-biV in those with suboptimal CRF (sRV-biV: 19.3 ± 3.5 vs. sLV: 16.9 ± 2.0 mL/kg/min, p=0.04, d=0.69) (Figure 1).

Conclusion: These results demonstrate that differences in CRF exist between patients with a sRV-biV compared to patients with a sLV, but only when stratifying according to the Weber criteria for optimal CRF. These differences may reflect different pathophysiological adaptations of a systemic right vs. a systemic left ventricle. The results could be used to design future studies to establish specific prognostic thresholds for patients with sRV-biV.