New index alpha improves detection of pulmonary hypertension in comparison with other cardiac magnetic resonance indices

Background: Cardiovascular magnetic resonance (CMR) has been proposed for the evaluation of patients with pulmonary hypertension (PH). However, there is no consensus on the optimal method for PH diagnosis using CMR. Objective: To compare the diagnostic ability of multiple CMR-derived indices for the detection of PH as determined by right heart catheterization (RHC). Methods: A total of 185 patients with known or suspected chronic PH who underwent cardiac CMR and RHC in ≤ 15 days were included. PH was defined as a mean pulmonary artery (PA) pressure ≥ 25 mm Hg. Right ventricular (RV) volumes, RV ejection fraction (RVEF), PA areas, and PA average blood flow velocity were quantified with CMR. A novel index α was defined as the ratio between minimal PA area and RVEF. Results: According to the RHC, PH was present in 152 patients. All CMR-derived parameters correlated with the degree of mean PA pressure, with α having the highest correlation coefficient (r = 0.61, p < 0.001). Correlations were also highest for α in the patients with pulmonary arterial hypertension (PAH; r = 0.55, p < 0.001) and non-PAH subgroup (r = 0.61, p < 0.001). Diagnostic accuracy for the detection of PH, based on receiver operating curve analysis, was best for α (area under the curve = 0.95). A cutoff value of 7.2 demonstrated a sensitivity of 90% and a specificity of 88%. Conclusions: An easily-obtainable and novel CMR index α that combines geometrical and functional information of the PA and the RV allows for the noninvasive diagnosis of PH with high accuracy, above other common CMR-derived parameters.