Risk Stratification and Outcomes in Patients With Pulmonary Hypertension: Insights into Right Ventricular Strain by MRI Feature tracking

BACKGROUND: Despite a recommended multidimensional approach for pulmonary hypertension (PH) risk stratification and guidance of treatment decisions, this may not always be achievable in patients with advanced disease. One issue is the lack of an imaging modality to assess right ventricular (RV) structure and function abnormalities. PURPOSE: To explore the risk stratification and prognostic value of cardiac MR feature tracking (MR-FT)-derived RV strain. STUDY TYPE: Retrospective. POPULATION: A total of 80 patients with idiopathic pulmonary artery hypertension (N = 52) or chronic thromboembolic PH (N = 28). FIELD STRENGTH: A 1.5 T or 3.0 T, balanced steady-state free precession sequence. ASSESSMENT: All patients underwent laboratory testing, right heart catheterization, and MR imaging (and in 37 cases, a cardiopulmonary exercise test was also performed) within a 1-month period. Cardiac functional parameters and both global longitudinal strain (GLS) and global circumferential strain (GCS) were analyzed. Patients were stratified into low, intermediate, and high-risk groups by guideline suggested stratified values of risk factors. The combined endpoint was death or hospitalization for congestive heart failure assessed during follow-up since the date of MR examination. STATISTICAL TESTS: tests or Fisher's exact test, receiver operating characteristic analysis, Kaplan-Meier survival analysis, and Cox regression analysis. A P value < 0.05 was considered statistically significant. RESULTS: The median follow-up duration was 3.4 years. Thirty-five patients presented with combined endpoint including 10 cardiac deaths. RV structural and deformation impairments were significantly associated with combined endpoint (ejection fraction: 31.3% ± 13.2% vs. 38.0% ± 14.8%, hazard ratio [HR: 0.974; GLS: -14.5 [-18.6, -10.9] % vs. -20.4 [-26.0, -13.2] %, HR: 1.071; GCS: -9.8 [-14.5, -7.3] % vs. -12.3 [-19.9, -8.4] %, HR: 1.059). There were significant differences in RVGLS among low, intermediate, and high-risk groups (-19.3% ± 7.2% vs. -17.3% ± 9.4% vs. -11.5% ± 4.4% by cardiac functional class, -21.8% ± 7.3% vs. -19.4% ± 8.2% vs. -12.7 ± 5.3% by NT-proBNP, -19.7% ± 7.7 vs. -15.8% ± 6.5% vs. -12.6% ± 8.2% by cardiac index). DATA CONCLUSION: RV deformation may aid risk stratification in patients with PH, providing crucial information for RV remodeling, pulmonary hemodynamic condition and exercise capacity. EVIDENCE LEVEL: 3 TECHNICAL EFFICACY: Stage 2.