Tricuspid regurgitation in pulmonary arterial hypertension: a right ventricular volumetric and functional analysis

The consequences of tricuspid regurgitation (TR) for right ventricular (RV) function and prognosis in pulmonary arterial hypertension (PAH) are poorly described and effects of tricuspid valve repair on the RV are difficult to predict.

In 92 PAH patients with available cardiac magnetic resonance (CMR) studies, TR volume was calculated as the difference between RV stroke volume and forward stroke volume, i.e. pulmonary artery (PA) stroke volume. Survival was estimated from the time of the CMR scan to cardiopulmonary death or lung transplantation. In a subgroup, pressure-volume loop analysis including two-parallel elastances was applied to evaluate effective elastances, including net afterload (effective arterial elastance (E _a)), forward afterload (effective pulmonary arterial elastance (E _pa)) and backward afterload (effective tricuspid regurgitant elastance (E _TR)). The effects of tricuspid valve repair were simulated using the online software package Harvi.

26% of PAH patients had a TR volume ≥30 mL. Greater TR volume was associated with increased N-terminal pro-brain natriuretic peptide (p=0.018), mean right atrial pressure (p<0.001) and RV end-systolic and -diastolic volume (both p<0.001). TR volume ≥30 mL was associated with a poor event-free survival (p=0.008). In comparison to E _a, E _pa correlated better with indices of RV dysfunction. Lower end-systolic elastance (E _es) (p=0.002) and E _TR (p=0.030), higher E _pa (p=0.001) and reduced E _es/E _pa (p<0.001) were found in patients with a greater TR volume. Simulations predicted that tricuspid valve repair increases RV myocardial oxygen consumption in PAH patients with severe TR and low E _es unless aggressive volume reduction is accomplished.

In PAH, TR has prognostic significance and is associated with low RV contractility and RV-PA uncoupling. However, haemodynamic simulations showed detrimental consequences of tricuspid valve repair in PAH patients with low RV contractility.