Cardiac Magnetic Resonance Assessment of Dyssynchrony and Myocardial Scar Predicts Function Class Improvement Following Cardiac Resynchronization Therapy

Abstract

STRUCTURED ABSTRACT Objective We tested a circumferential mechanical dyssynchrony index (circumferential uniformity ratio estimate, or CURE; 0–1, 1=synchrony) derived from magnetic resonance myocardial tagging (MR-MT) for predicting clinical function class improvement following cardiac resynchronization therapy (CRT). Background There remains a significant nonresponse rate to CRT, with recent data questioning the reproducibility of standard echocardiography-based dyssynchrony metrics. MR-MT provides high quality mechanical activation data throughout the heart, and delayed enhancement magnetic resonance imaging (DEMRI) offers precise characterization of myocardial scar and scar distribution. Methods MR-MT was performed in patients with cardiomyopathy, divided into: 1) a CRT-HF cohort (n=20) with mean (SD) LVEF 0.23 (0.057) in order to evaluate the clinical use of MR-MT and DEMRI prior to CRT; and 2) a multimodality cohort (n=27) with mean (SD) LVEF 0.20 (0.066) in order to compare MR-MT and tissue Doppler imaging (TDI) assessments of mechanical dyssynchrony. MR-MT was also performed in 9 healthy control subjects. Results MR-MT showed that control subjects had highly synchronous contraction (mean [SD] CURE 0.96 [0.01]) while TDI septal-lateral delay indicated dyssynchrony in 44% of normal controls. Using a cutoff of <0.75 for CURE based on ROC analysis (AUC 0.889), 56% of patients tested positive for mechanical dyssynchrony, and the MR-MT CURE predicted improved function class in CRT-HF patients with 90% accuracy (PPV 87%; NPV 100%). Adding DEMRI (% total scar<15%) data improved accuracy further to 95% (PPV 93%; NPV 100%). The correlation between CURE and QRSd was modest in all cardiomyopathy subjects (r=0.58, p<0.001), and somewhat less in the CRT-HF group (r=0.40, p=0.08). The multimodality cohort showed a 30% discordance rate between CURE and TDI septal-lateral delay. Conclusions MR-MT assessment of circumferential mechanical dyssynchrony predicts improvement in function class after CRT. The addition of scar imaging by DEMRI further improves this predictive value.

Optimal site selection and image fusion guidance technology to facilitate cardiac resynchronization therapy

“…Several dyssynchrony assessment metrics have been proposed including myocardial tagging, displacement encoding with stimulated echoes, and phase contrast tissue velocity mapping. While myocardial tag data has been shown to predict functional improvement following CRT implantation [94], tag decay remains an issue and this led to the development of 3D volumetric change as a means of assessing both global LV dyssynchrony and assessing mechanical activation [95]. When compared to other mechanical dyssynchrony measures, volume changeSDI proved the sole predictor of chronic reverse remodeling [18].…”

Cardiovascular MRI for the assessment of heart failure: Focus on clinical management and prognosis

“…There is hope, that novel CMR technology will have a superior reproducibility for the assessment of dyssynchrony and, therefore, provide greater accuracy in predicting response to CRT. Recent reports showed promising results using CMR techniques to predict response to CRT (80)(81)(82). Moreover, not only the severity of dyssynchrony, but also the amount of scar tissue and the spatial relation of myocardial scar and the site of LV pacing are important for CRT response.…”

New insights in LV torsion for the selection of cardiac resynchronisation therapy candidates

“…Strain parameters such as the circumferential uniformity ratio estimate (CURE) show promising results [7,8]. In addition, recently LV torsion was assessed as a measure for prediction of CRT response.…”