Abstract 2512: Magnetic Resonance Imaging Assessment of Circumferential Mechanical Dyssynchrony in Heart Failure Predicts Response to Cardiac Resynchronization Therapy
Introduction: The purpose of this study was to determine if quantitative circumferential strain assessment using magnetic resonance imaging myocardial tissue tagging (MRI-MT) predicts response to cardiac resynchronization therapy (CRT).
Methods: We performed a retrospective analysis of n = 50 cardiomyopathy patients (age 62 ± 11 years, 60% ischemic cardiomyopathy, left ventricular ejection fraction 24 ± 9.4 %) referred for implantable cardioverter defibrillators (ICDs), including n = 20 with CRT, in addition to n = 8 normal patients for controls. All cardiomyopathy patients had MRI-MT and 12-lead electrocardiograms prior to implant, and 38 patients had standard 2D/M-mode echocardiography. MRI-based mechanical dyssynchrony (MD) was indexed by the circumferential uniformity ratio estimate (CURE; 0 = dyssynchrony, 1 = synchrony), and the M-mode echocardiogram was also analyzed for MD.
Results: Normal subjects (n = 8) had highly synchronous contraction (CURE = 0.97 +/- 0.01), establishing a normal CURE > 0.90. In the 50 subjects with cardiomyopathy, there was a significant correlation between CURE and QRSd (R = 0.69, p < 0.001). In patients with CRT and class III heart failure status, baseline CURE predicted clinical improvement (p = 0.003), and a CURE cutoff of < 0.75 had 100% sensitivity and 80% specificity for identifying clinical responders (Panel A). Response based on QRSd (B) and septal-to-posterior wall motion delay (SPWMD) from the M-mode echocardiogram (C) is also shown. CURE was moderately correlated with the SPWMD when patients with septal akinesis were excluded (R = 0.47, p = 0.0017).
Conclusions: MRI-MT assessment of circumferential MD predicts response to CRT.