Cardiac magnetic resonance-derived right ventricular outflow tract systolic flow acceleration: a novel index of right ventricular function and prognosis in patients with pulmonary arterial hypertension.

To validate the right ventricular outflow tract systolic flow acceleration (RVOTACC; peak flow velocity/time-to-peak velocity) measured by phase-contrast (PC)-cardiovascular magnetic resonance (CMR) as a novel index of right ventricular (RV) function, and to investigate its clinical implications in patients with pulmonary arterial hypertension (PAH). Thirty (38% male, 43 ± 15 years old) out of 55 consecutive patients who were initially diagnosed with PAH at the referral center were prospectively enrolled between March 2009 and July 2010 and were followed for PAH-related cardiovascular events for 2 years. The invasively measured maximum dP/dt (dP/dtmax) was used as an index of RV contractility. The PC-CMR-derived RVOTACC was compared with well-known prognostic parameters. The PC-CMR-derived RVOTACC correlated strongly with the dP/dtmax and estimated RV function more accurately than the CMR-derived RV ejection fraction. The CMR-derived RVOTACC level (HR = 0.87, 95% CI 0.78-0.98, p = 0.038) could be another powerful prognostic index compared with the functional capacity (hazard ratio [HR] = 0.88, 95% confidence interval [CI] 0.78-0.97, p = 0.035) and REVEAL Registry risk score (HR = 0.83, CI 0.56-0.95, p = 0.012). Furthermore, receiver-operating characteristic analysis identified ≥0.4 m/s2 as the optimal RVOTACC cut-off for predicting subsequent cardiovascular events. PC-CMR-derived RVOTACC is a promising non-invasively measured index of RV function and prognosis in patients with PAH.