Cardiac magnetic resonance T1 mapping predicts outcome in patients with a systemic right ventricle: a sub-analysis of the SERVE study

Aims In patients with a systemic right ventricle (sRV), the sRV is faced with an increased afterload compared to a right ventricle in sub-pulmonary position, leading to the development of fibrosis followed by ventricular dysfunction. Cardiac magnetic resonance (CMR) T1 mapping (T1) and its derived parameter, such as the extracellular volume (ECV), allow quantification of interstitial fibrosis. The SERVE study, a multicentric, placebo-controlled trial evaluated the effect of tadalafil in sRV patients. The aim of this sub-analysis of the SERVE trial was to evaluate (i) the relationship between T1 mapping parameters and the clinical composite endpoint of hospitalization for heart failure, clinically relevant arrhythmias, and all-cause mortality and (ii) their evolution over time, their correlation with CMR functional parameters, and the impact of study treatment. Methods and results Patients included in the SERVE trial underwent a 1.5T CMR at baseline and at 1- and 3-year follow-up. For each CMR exam, native and post-contrast T1, as well as ECV, were calculated. In addition, late gadolinium enhancement (LGE) imaging was performed. Cardiac magnetic resonance was available for 60 patients. Native sRV T1 and ECV above the 75th percentile, but not LGE, were associated with the clinical composite endpoint. There was no significant change and no influence of tadalafil treatment on sRV T1 and ECV. Conclusion T1 mapping as a non-invasive biomarker of the degree of myocardial fibrosis predicts outcome in patients with sRV and should be incorporated in risk stratification in these patients. The phosphodiesterase-5 inhibitor tadalafil appears to have no impact on the development of interstitial or macroscopic fibrosis.