Ventriculo-arterial coupling parameters by cardiac magnetic imaging are associated with outcome in patients with a systemic right ventricle

Abstract Introduction Invasive studies have shown that patients with a systemic right ventricle (sRV) due to congenitally corrected transposition of the great arteries (TGA) or complete TGA after atrial switch procedure possess impaired ventriculo-arterial coupling (VAC) parameters. The randomized, placebo-controlled, double-blinded, multi-centre SERVE trial investigated the effect of phosphodiesterase-5 inhibitor tadalafil in sRV patients on RV endsystolic volume (RVESV), with negative results. Aim of this sub-analysis was to evaluate changes of non-invasively assessed VAC parameters over time and for treatment effect. We prospectively analysed whether VAC parameters predict clinical outcome in sRV patients. Methods Volumetric RV parameters and aortic flow were assessed by cardiac magnetic resonance (CMR) and analysed (blinded for patient and assessment time and treatment) at baseline, after 3 years, or after 1 year if the study drug was withdrawed. Parameters were compared with clinical outcome at each visit. Effective arterial elastance Ea was calculated as RV endsystolic pressure (RVesp) / aortic forward flow, with RVesp defined as 0.9 x systolic blood pressure. Right ventricular endsystolic elastance Ees was calculated by RVesp / RVESV, and RV VA-coupling ratio was expressed as Ea/Ees. Treatment effect was analysed using ANCOVA with baseline values and FU-time as covariates. Values of > 4th quartile were used as cut-off for Kaplan-Meier analysis on the primary outcome, defined as a composite of all-cause death, clinically relevant arrhythmias and hospitalisation for heart failure. Results CMR exams were available for 78 patients at baseline (40±11 years, 33% females) and for 71 patients at follow-up (FU). No effect of tadalafil compared to placebo was evident for effective arterial elastance Ea (p=0.35), ventricular endsystolic elastance Ees (p=0.11), VAC Ea/Ees (p=0.82), RVESVi (p=0.63) and RV ejection fraction (RVEF, p=0.6). Over the 3 years FU-time, Ea (p=0.24) and RVEF (p=0.11) did not change, whereas Ees mildly decreased (p=0.0052, fig. 1 A) and Ea/Ees increased (p=0.013, fig. 1 B). During FU, 14 patients experienced a clinical event. An Ees <0.73 mmHg/ml and an Ea/Ees ratio of >1.94 were associated with adverse clinical outcomes (for both p=0.004, fig. 2). Conclusion In sRV patients, treatment with tadalafil had no effect on VAC parameters compared to placebo. CMR-derived ventricular endsystolic elastance (Ees) and Ea/Ees ratio changed over the FU of 3 years and were associated with adverse clinical outcome.Figure 1Figure 2