Left ventricular end-systolic elastance (Ees), arterial elastance (Ea) and ventricular arterial coupling (VAC) (ratio of Ea/Ees) has been considered “gold” standard to assess ventricular contractility and performance. Ventricular arterial uncoupling due to impaired Ees or augmented Ea impaired ventricular mechanical efficiency (ME) and cardiac output. Ventricular contractility and arterial loading and the degree of their mismatching have yet been studied in pulmonary hypertension (PH). A total of 42 PH subjects who underwent both cardiac magnetic resonance (CMR) and right heart catheterization (RHC) were categorized into three groups – preserved LV ejection fraction (LVEF > 50%) and VAC < 0.8 (group 1); preserved LVEF and VAC > 0.8 (group 2); reduced LVEF (< 50%) (group 3). The results showed that VAC was correlated negatively with ME, which indicated arterial-ventricular uncoupling impaired mechanical efficiency. Importantly, the group 2 with ventricular arterial uncoupling had impaired mechanical efficiency despite its preserved ejection fraction.