40 Validation of pulmonary acceleration time as a non-invasive estimate of pulmonary artery pressure in patients with preserved right ventricular function

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Background Estimating pulmonary artery pressure (PAP) via tricuspid regurgitation (TR) velocity is standard in echocardiography, but it can be unreliable in the absence of TR or when the Doppler signal is poor. Pulmonary acceleration time (PAT), measured as the time from onset to peak flow in the pulmonary artery, is a potential alternative marker. Since PAT is affected by right ventricular (RV) systolic function, this study focuses on patients with preserved RV function to evaluate PAT’s reliability for PAP estimation, independent of RV impairment. Objective To evaluate the correlation between PAT and TR-derived systolic PAP in patients with preserved RV systolic function, and to assess how PAT varies with different levels of pulmonary hypertension (PH). Methods This prospective study included patients with suspected PH and preserved RV systolic function, defined by a tricuspid annular plane systolic excursion (TAPSE) between 2.0 and 2.6 cm. PAT was measured using pulsed-wave Doppler at the level of the pulmonary valve, while systolic PAP was calculated from TR velocity. Patients were categorized based on PH severity, and correlations between PAT and PAP were analysed. Results PAT was inversely correlated with systolic PAP (r = -0.78, p < 0.001). PAT decreased progressively with increasing PAP averaging 140ms in mild PH (15–20 mmHg), around 95ms in moderate PH (45–55 mmHg), and plateauing at approximately 100ms in severe PH (≥70 mmHg). This plateau may reflect early subclinical RV dysfunction. Importantly, PAT values remained consistent across the TAPSE-controlled cohort, confirming minimal influence from RV contractility. Conclusion PAT is a simple, reproducible, and TR-independent marker for estimating PAP in patients with preserved RV function. While its accuracy diminishes at higher pressure levels, PAT remains a valuable tool for non-invasive PH assessment, especially when TR measurements are unavailable or unreliable.

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