Corrected MRI Pulmonary Transit Time for Identification of Combined Precapillary and Postcapillary Pulmonary Hypertension in Patients With Left Heart Disease

Background The identification of combined precapillary and postcapillary pulmonary hypertension (CpcPH) in patients with pulmonary hypertension (PH) due to left heart disease (LHD) can influence therapy and outcome and is currently based on invasively determined hemodynamic parameters. Purpose To investigate the diagnostic value of MRI-derived corrected pulmonary transit time (PTTc) in PH-LHD sub-grouped according to hemodynamic phenotypes. Study Type Prospective observational study. Population A total of 60 patients with PH-LHD (18 with isolated postcapillary PH [IpcPH] and 42 with CpcPH), and 33 healthy subjects. Field Strength/Sequence A 3.0 T/balanced steady-state free precession cine and gradient echo-train echo planar pulse first-pass perfusion. Assessment In patients, right heart catheterization (RHC) and MRI were performed within 30 days. Pulmonary vascular resistance (PVR) was used as the diagnostic "reference standard." The PTTc was calculated as the time interval between the peaks of the biventricular signal-intensity/time curve and corrected for heart rate. PTTc was compared between patient groups and healthy subjects and its relationship to PVR assessed. The diagnostic accuracy of PTTc for distinguishing IpcPH and CpcPH was determined. Statistical Tests Student's t-test, Mann-Whitney U-test, linear and logistic regression analysis, and receiver-operating characteristic curves. Significance level: P < 0.05. Results PTTc was significantly prolonged in CpcPH compared with IpcPH and normal controls (17.28 +/- 7.67 vs. 8.82 +/- 2.55 vs. 6.86 +/- 2.11 seconds), and in IpcPH compared with normal controls (8.82 +/- 2.55 vs. 6.86 +/- 2.11 seconds). Prolonged PTTc was significantly associated with increased PVR. Furthermore, PTTc was a significantly independent predictor of CpcPH (odds ratio: 1.395, 95% confidence interval: 1.071-1.816). The area under curve was 0.852 at a cut-off value of 11.61 seconds for PTTc to distinguish between CpcPH and IpcPH (sensitivity 71.43% and specificity 94.12%). Data Conclusion PTTc may be used to identify CpcPH. Our findings have potential to improve selection for invasive RHC for PH-LHD patients. Evidence Level 3 Technical Efficacy Stage 2