Diameter of the Pulmonary Artery in Relation to the Ascending Aorta: Association with Cardiovascular Outcome.

Purpose To investigate whether the pulmonary artery (PA)-to-ascending aorta (Ao) ratio is associated with outcome in unselected patients referred for cardiac magnetic resonance (MR) imaging. Materials and Methods This study prospectively enrolled 650 consecutive patients (47.2% women; mean age, 56.1 years ± 17.7 [standard deviation]). Diameters of PA and Ao were measured in axial black blood images. On the basis of previous results, a PA-to-Ao ratio of 1.0 or greater was chosen as the cutoff for further analysis. Univariable and multivariable Cox regression models were used to investigate the primary end point, which was defined as a composite of cardiovascular hospitalization and death. Results A PA-to-Ao ratio of 1.0 or greater was present in 131 (20.2%) patients. Patients with a PA-to-Ao ratio of 1.0 or greater were predominantly women (P = .010); more frequently presented with atrial fibrillation (P < .001), diabetes (P < .001), and impaired renal function (P < .001); and had higher N-terminal pro-B-type natriuretic peptide (NT-proBNP) levels (P < .001), larger left (P = .023) and right ventricles (RV; P = .002), and worse RV function (P < .001). Patients were followed for 17.8 months ± 12.9, during which 110 patients (16.9%) reached the primary end point. By Kaplan-Meier analysis, event-free survival was significantly worse in patients with a PA-to-Ao ratio of 1.0 or greater (log-rank test, P < .001). A PA-to-Ao ratio of 1.0 or greater was independently associated with outcome by multivariable Cox regression analysis, in addition to age, NT-proBNP serum levels, and RV size. Conclusion A PA-to-Ao ratio of 1.0 or greater identified patients at risk, most likely because of elevated PA pressures. On the basis of these results, the PA-to-Ao ratio should routinely be reported at cardiac MR imaging. © RSNA, 2017 Online supplemental material is available for this article.

Diagnostic and Prognostic Utility of Cardiac Magnetic Resonance Imaging in Aortic Regurgitation.

OBJECTIVES: This study investigated the diagnostic and prognostic value of cardiac magnetic resonance (CMR) imaging in chronic aortic regurgitation (AR). BACKGROUND: Accurate quantification of AR severity by echocardiography frequently remains difficult. CMR is recommended as the complementary method; however, its accuracy and prognostic utility remain unknown. METHODS: A total of 232 consecutive patients (34.5% were females 55.5 ± 19.8 years of age) with chronic AR (including 40 with moderate to severe and 44 with severe AR on echocardiography) underwent CMR within 4 weeks of echocardiography. CMR included phase-contrast velocity-encoded imaging for the measurement of regurgitant volume and fraction at the sinotubular junction and assessment of holodiastolic retrograde flow (HRF) in the descending aorta. Significant AR was defined as the presence of HRF on CMR. Patients were followed prospectively, and multivariate Cox regression was applied for outcome analysis using a combination of heart failure, hospitalization, and cardiovascular death as primary endpoint. RESULTS: AR severity on the basis of echo was reclassified in a significant number of patients according to CMR: 6.8% with mild AR on echo had HRF on CMR, whereas 34.1% with severe AR on echo did not have HRF on CMR and were reclassified as having nonsignificant AR. In 40 patients with uncertain AR severity (moderate to severe) on echo, 45.0% had HRF on CMR, indicating severe AR. Patients were followed for 35.3 ± 26.6 months. During that period, 63 patients (27.2%) reached the combined endpoint, including 43 (18.5%) with heart failure hospitalizations and 20 (8.6%) with cardiovascular deaths. By multivariate regression analysis, including clinical as well as imaging parameters, only N-terminal pro-B-type natriuretic peptide concentration (hazard ratio: 2.184 [95% confidence interval: 1.468 to 3.248]; p < 0.001) and HRF on CMR (hazard ratio: 2.774 [95% confidence interval: 1.131 to 6.802]; p = 0.026) remained significantly associated with outcome. CONCLUSIONS: In chronic AR, CMR has the potential to add important diagnostic and prognostic information.

T1 Mapping by CMR Imaging: From Histological Validation to Clinical Implication.

OBJECTIVES: The purpose of this study was to prospectively investigate the diagnostic and prognostic impact of cardiac magnetic resonance (CMR) T1 mapping and validate it against left ventricular biopsies. BACKGROUND: Extracellular volume (ECV) expansion is a key feature of heart failure. CMR T1 mapping has been developed as a noninvasive technique to estimate ECV; however, the diagnostic and prognostic impacts of this technique have not been well established. METHODS: A total of 473 consecutive patients referred for CMR (49.5% female, age 57.8 ± 17.1 years) without hypertrophic cardiomyopathy, cardiac amyloidosis, or Anderson-Fabry disease were studied. T1 mapping with the modified Look-Locker inversion recovery (MOLLI) sequence was used for ECV calculation (CMR-ECV). For methodological validation, 36 patients also underwent left ventricular biopsy, and ECV was quantified by TissueFAXS analysis (TissueFAXS-ECV). To assess the prognostic value of CMR-ECV, its association with hospitalization for cardiovascular reasons or cardiac death was tested in a multivariable Cox regression model. RESULTS: TissueFAXS-ECV was 26.3 ± 7.2% and was significantly correlated with CMR-ECV (r = 0.493, p = 0.002). Patients were followed up for 13.3 ± 9.0 months and divided into CMR-ECV tertiles for Kaplan-Meier analysis (tertiles were ≤ 25.7%, 25.8% to 28.5%, and ≥ 28.6%). Significantly higher event rates were observed in patients with higher CMR-ECV (log-rank p = 0.013). By multivariable Cox regression analysis, CMR-ECV was independently associated with outcome among imaging variables (p = 0.004) but not after adjustment for clinical parameters. CONCLUSIONS: CMR T1 mapping allows accurate noninvasive quantification of ECV and is independently associated with event-free survival among imaging parameters. Its prognostic value on top of established clinical risk factors warrants further investigation in long-term studies.