Pulmonary artery acceleration time in identifying pulmonary hypertension patients with raised pulmonary vascular resistance.

Background In patients with pulmonary hypertension (PH), ascertaining raised vascular resistance as a cause is a clinical objective, for which various Doppler-based measurements have been proposed, but with modest accuracy. We hypothesize that pulmonary acceleration time (PAcT) and the ratio of PAcT/peak pulmonary artery systolic pressure (PASP) reflect better the extent of the vascular resistance, compared with other available methods, and can differentiate ac- curately between pre- and post-capillary PH. Methods and results We investigated 56 patients (mean age 61+13 years, 23 males) in a simultaneous echocardiography and right heart catheterization (RHC) study. Based on the RHC, pulmonary vascular resistance (PVR), and pulmonary capillary wedge pressure (PCWP), patients were divided into four groups: Group 1 ¼ normal PVR (,3 WU (Wood units)) and PCWP (,12 mmHg), Group 2 ¼ raised PVR but normal PCWP, Group 3 ¼ raised PVR and PCWP; and Group 4 ¼ normal PVR but raised PCWP. We used spectral Doppler to measure PAcT (corrected for heart rate) and to estimate PASP (peak tricuspid regurgitation pressure drop + estimated right atrial pressure of 7 mmHg). We also tested other available methods for assessing PVR. There were small age differences between patient groups but no age difference between Groups 2 and 4. PAcT and PAcT/PASP were both significantly (P ¼ 0.008) reduced in Groups 2 and 3 compared with Groups 1 and 4. PAcT ≤90 had an 84% sensitivity and an 85% specificity in identifying patients with PVR ≥3 WU with a positive and a negative predictive value of 88% and 81%, respectively. The non-linear relationship between PVR and PAcT gave a quadratic r ¼ 0.61, P , 0.001. ROC curve analysis showed PAcT having the best accuracy (83%) in detecting a PVR ≥3 WU. Conclusion PAcT ,90 ms can serve as a strong non-invasive predictor of PVR .3 WU, which could differentiate patients with