BACKGROUND: Although increased pulmonary pressure is caused by changes in the pulmonary vasculature, prognosis in idiopathic pulmonary arterial hypertension (IPAH) is strongly associated with right ventricular (RV) function. The aim of this study was to describe the best RV adaptive remodeling pattern to increased afterload in IPAH. METHODS: In 60 consecutive patients with IPAH, RV morphologic and functional features were evaluated by echocardiography and cardiac magnetic resonance imaging. To address the question of the best RV adaptation pattern, we divided the study population into two groups by the median value of RV mass/volume ratio (0.46) because this parameter allows the distinction between RV eccentric (≤0.46) and concentric hypertrophy (>0.46). The two groups were compared for RV remodeling and systolic function parameters, World Health Organization class, pulmonary hemodynamics, and 6-minute walk test. RESULTS: Despite similar pulmonary vascular resistance, mean pulmonary pressure, and compliance, patients with eccentric hypertrophy had advanced World Health Organization class and worse 6-minute walk test, hemodynamics, RV remodeling, and systolic function parameters compared with patients with concentric hypertrophy. The group with concentric hypertrophy had higher RV to pulmonary arterial coupling compared with the group with eccentric hypertrophy (1.24 ± 0.26 vs 0.83 ± 0.33, p = 0.0001), indicating higher RV efficiency. A significant correlation was found between pulmonary vascular resistance and RV to pulmonary arterial coupling (r = -0.55, r(2) = 0.31, p = 0.0001), with patients with RV mass/volume ratio > 0.46 at the higher part of the scatterplot, confirming more adequate RV function. CONCLUSIONS: Concentric hypertrophy might represent a more favorable RV adaptive remodeling pattern to increased afterload in IPAH because it is associated with more suitable systolic function and mechanical efficiency.