Prognostic value of echocardiographic estimation of pulmonary vascular resistance in patients with acute pulmonary thromboembolism

Background: Noninvasive calculation of pulmonary vascular resistance (PVR) has been reported to be feasible. We therefore evaluated whether baseline PVR could predict clinical outcomes in patients with acute pulmonary thromboembolism (aPTE). Methods: The study cohort consisted of 54 patients with aPTE who underwent both pretreatment and follow-up echocardiography. Doppler-derived PVR was calculated using the following equation: PVR (Woods unit [WU]) = (peak tricuspid regurgitant velocity [TRV_max]/time-velocity integral of right ventricular outflow tract) × 10 + 0.16. Adverse clinical events included all-cause death and persistent pulmonary hypertension (TRV _max >3.5 m/sec) on follow-up echocardiography. Results: During a clinical follow-up time of 2.4 ± 1.7 years, 16 patients experienced adverse events (death [n = 14]; persistent pulmonary hypertension [n = 8]). Patients who developed adverse events were significantly older than those who did not (68.0 ± 13.8 years vs 56.9 ± 15.4 years, P = .02) and showed higher initial PVR (4.5 ± 1.4 WU vs 3.5 ± 1.0 WU, P = .01) and TRV_max (3.9 ± 0.6 m/sec vs 3.6 ± 0.5 m/sec, P = .02). The best cutoff value of PVR for predicting adverse events was 4.5 WU (area under the curve = 0.71, P = .02), with a sensitivity and specificity of 63% and 90%, respectively. PVR >4.5 WU (hazard ratio 5.68; 95% CI, 1.89-16.95; P = .002) and older age (hazard ratio per 10 years = 1.47; 95% CI, 1.02-2.12; P = .04) were independent factors associated with the development of adverse events. The 6-year overall survival (16% ± 14% vs 87% ± 6%, P < .0001) and event-free survival (15% ± 13% vs 84% ± 6%, P < .0001) rates differed according to initial PVR. Conclusion: Echocardiographic estimation of PVR provides important prognostic information in patients with aPTE.