Dobutamine stress for evaluation of right ventricular reserve in pulmonary arterial hypertension.

Right ventricular contractile response to pharmacological stress in pulmonary arterial hypertension (PAH) has not been characterised. We evaluated right ventricular contractile reserve in adults with PAH using dobutamine stress echocardiography. 16 PAH patients and 18 age-matched controls underwent low-dose dobutamine stress echocardiography. Contractile reserve was assessed by the change (Δ; peak stress minus rest value) in tricuspid annular plane systolic excursion (TAPSE) and tricuspid annular systolic velocity (S'). A subgroup of 13 PAH patients underwent treadmill cardiopulmonary exercise testing for peak oxygen uptake (V'O2peak). At rest, TAPSE and S' were reduced in the PAH group compared with controls (1.7 ± 0.4 versus 2.4 ± 0.2 cm and 9.7 ± 2.6 versus 12.5 ± 1.2 cm · s(-1), respectively; p<0.05). Contractile reserve was markedly attenuated in PAH compared to controls (ΔTAPSE 0.1 ± 0.2 versus 0.6 ± 0.3 cm and ΔS' 4.6 ± 2.8 versus 11.2 ± 3.6 cm · s(-1); p<0.0001). In the sub-group of PAH patients with preserved right ventricular systolic function at rest, contractile reserve remained depressed compared to controls. V'O2peak was significantly correlated with ΔS' (r=0.87, p=0.0003) and change in stroke volume (r=0.59, p=0.03). Dobutamine stress can reveal sub-clinical reduction in right ventricular contractile reserve in patients with PAH. A correlation with exercise capacity suggests potential clinical value beyond resting measurements.