Long-term prognostic value of native myocardial tissue relaxation parameters (T1, T2, and T1ρ) in patients with precapillary pulmonary hypertension

Quantitative native cardiovascular magnetic resonance imaging (CMR) techniques such as T1, T2, and T1ρ mapping can provide myocardial tissue characteristics non-invasively. The objective of this study was to evaluate the alterations of T1, T2, and T1ρ in patients with precapillary pulmonary hypertension (PH) and their prognostic value. We prospectively enrolled 35 PH patients and 15 healthy controls between 2014 and 2017. PH patients were followed for all-cause death. CMR functional and tissue relaxation parameters were acquired and analyzed. Multivariate Cox regression models and time-dependent receiver operator characteristic (ROC) curves were constructed to determine the risk assessment/predictive value of T1, T2, and T1ρ for all-cause mortality. During a median follow-up of 79 months (Interquartile range 40-103 months), 15 out of 34 patients died. Compared with healthy controls, T1, T2, and T1ρ values were significantly higher in patients with precapillary PH. T1, T2, and T1ρ values at right ventricular (RV) insertion points (IPs) showed the high correlation with RV functional parameters. T1_RVIP showed the highest predictive value in time-dependent ROC analysis for all-cause mortality during the entire observation time (3-9 years). T2_RVIP of 56.1 ms showed the highest value predictive of 3-year mortality with an AUC of 0.950 (sensitivity: 1.000, specificity 0.824) and T1_RVIP of 1215.2 ms had excellent discrimination of AUC of 0.870 (sensitivity: 0.946, specificity 0.922). According to Kaplan-Meier analyses, a native T1_RVIP of 1215.2 ms (P = 0.003), a native T2_RVIP of 56.1 ms (P = 0.002), and a native T1ρ_RVIP of 109.5 ms (P = 0.005), were predictive of all-cause mortality. In univariate Cox regression models, T1_RVIP, T2_RVIP, and T1ρ_RVIP, as well as RVEDVi and NT-proBNP, are predictive of all-cause-mortality. In multivariate analyses, T2_RVIP was the sole independent predictor for mortality (hazard ratio, 2.5, [1.1-5.9], P = 0.035). Native tissue relaxation parameters T1, T2, and T1ρ at RVIPs are highly correlated with RV functional parameters and may have prognostic value. T2_RVIP is independently predictive of all-cause mortality in precapillary PH during long-term follow-up in this small prospective study.