Doppler Echocardiography Pulmonary Artery Flow Acceleration Time: An Adjunctive Parameter To Select Candidates With Suspected Pulmonary Hypertension To Proceed To Right Heart Catheterization

Background: Pulmonary hypertension (PH) is associated with a worsening prognosis especially if specific treatment is delayed. The gold standard technique for diagnosis of PH is right heart catheterization (RHC), an invasive procedure associated with several complications. European Society of Cardiology (ESC) Guidelines for the management of PH identify the echocardiographic estimation of systolic pulmonary arterial pressure (sPAP) from tricuspid regurgitation velocity (TRV) as the method of choice for selecting patients (pt) eligible for RHC. However, several studies indicate that echocardiographic TRV and sPAP estimation have high specificity for PH diagnosis only when moderately elevated (TRV>3.4 m/sec, sPAP>50 mmHg). Indeed, for TRV>2.9 m/sec but <3.4 m/sec, many false positive pt undergo unnecessary RHC. The measurement of the acceleration time (Act) of pulmonary artery flow has been increasingly used as an index of increased right ventricular pressure and thus of PH. Our aim was to test the efficacy of Act as an additional screening parameter for the selection of pt eligible for RHC. Methods: 56 pt (22 males) with clinically suspected PH underwent echocardiographic evaluation and subsequent RHC within 48 hours in order to measure TRV, sPAP, and Act (echocardiography), sPAP, mean PAP, diastolic PAP and pulmonary vascular resistances (PVR) (RHC). All echocardiograms were performed by a single experienced operator. A receiver-operator curve (ROC) was constructed to assess the cut-off value of Act with the highest sensitivity and specificity for the diagnosis of increased PVR. Results: Among the 48 pt diagnosed with PH after RHC (mean PAP>25mmHg), echocardiographic sPAP and TRV were higher than in pt without PH, with a statistically significant difference (p<0.05). Act was shorter (p<0.05) in pt with PH than in healthy controls, and using the Pearson correlation coefficient (r) it showed a good correlation with mean PAP (r=0.601), stronger than with PVR (r=0.492). The value of Act was independent from right ventricular dysfunction as assessed by tricuspid annulus plane systolic excursion (TAPSE, r=0.3). A high specificity (98%) for diagnosis of increased mean PAP was found at an Act value of 113 msec. Conclusion: Combined with a TRV value >2.9 m/sec, the cut-off value of 113 msec assures to the parameter Act a high specificity (98%) for the diagnosis of increased mean PAP, thus indicating that Act can be a useful tool for screening pt with suspected PH to proceed to RHC when combined with intermediate values of TRV.