Right Ventricular Remodeling in Idiopathic Pulmonary Arterial Hypertension: Concentric Versus Eccentric Hypetrophy

Although increased pulmonary pressure is caused by changes in the pulmonary vasculature, prognosis in idiopathic pulmonary arterial hypertension (IPAH) is strongly associated to right ventricular (RV) function. The aim of this study was to describe the best RV adaptive remodeling pattern to increased afterload in IPAH. In 60 consecutive IPAH patients RV morphological and functional features were evaluated by echocardiographic and magnetic resonance imaging. To address the question of the best RV morphological adaptation pattern, we decided to divide the study population into two groups by the median value of RV M/V ratio (0.46), as this parameter allows the distinction between RV eccentric hypertrophy (≤0.46) and concentric hypertrophy (>0.46). The two groups were compared for RV remodeling and systolic function parameters, WHO class, pulmonary hemodynamics and 6-minute walk test (6MWT). Despite similar pulmonary vascular resistance (PVR), mean pulmonary pressure and compliance, patients with eccentric hypertrophy had advanced WHO class, worse 6MWT, RV hemodynamics, RV remodeling and systolic function parameters compared to patients with concentric hypertrophy. Interestingly, the latter group has higher RV to pulmonary arterial coupling (VA coupling) compared to the other (1.24±0.26 vs 0.83±0.33; p=0.0001), indicating higher RV efficiency. A significant correlation was found between PVR and VA coupling (r=-0.55, r2=0.31, p=0.0001), with those patients with RV M/V ratio >0.46 at the higher part of the scatterplot, confirming a more adequate RV function. Concentric hypertrophy might represent a more favorable RV adaptive remodeling pattern to increased chronic afterload in IPAH, as it is associated to a more suitable RV systolic function and mechanical efficiency.