Time-Velocity Integral of Left Ventricular Outflow Tract Predicts Worse Long-Term Survival in Pulmonary Arterial Hypertension

The time-velocity integral of the left ventricular outflow tract (TVILVOT) has been demonstrated to correlate with heart failure hospitalization and mortality, but the association of TVILVOT with the severity and prognosis of pulmonary arterial hypertension (PAH) has not been evaluated. The aim of this study was to investigate the predictive value of baseline TVILVOT in PAH. A total of 225 consecutive patients with a diagnosis of incident PAH were prospectively studied and echocardiology-derived TVILVOT was measured at enrollment followed by right heart catheterization examination within 48 hours. Cox proportional hazards analysis was performed to assess the association between baseline variables and mortality. During a median follow-up period of 33.8 months, 44 patients died of cardiovascular events. Baseline TVILVOT was significantly lower in the nonsurvivors compared with the survivors (P < 0.001). Baseline TVILVOT was positively correlated with stroke volume obtained by right heart catheterization (r = 0.709; P < 0.001), and inversely correlated with N-terminal pro–B-type natriuretic peptide (r = −0.533; P < 0.001), pulmonary vascular resistance (r = −0.423; P < 0.001). Multivariate analysis showed that baseline TVILVOT (hazard ratio: 0.856; 95% CI: 0.780-0.941; P = 0.001) was an independent predictor of cardiovascular mortality in PAH. Patients with a baseline TVILVOT <17.1 cm (median value) had a significantly worse survival than those with a baseline TVILVOT ≥17.1 cm (P < 0.001). The findings of this study suggest that noninvasive TVILVOT provides a practical method to assess the severity and predict long-term outcome of PAH.