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

Kenneth C. Bilchick, MD, FACC^_*, Veronica Dimaano, MD^_*, Katherine C. Wu, MD^_*, Robert H. Helm, MD^_*, Robert G. Weiss, MD^_*, Joao A. Lima, MD^_*, Ronald D. Berger, MD, PhD^_*, Gordon F. Tomaselli, MD, FAHA, FACC, FHRS^_*, David A. Bluemke, MD, PhD, FAHA, Henry R. Halperin, MD, FAHA^_*,,, Theodore Abraham, MBBS, MD^_*, David A. Kass, MD, FAHA^_*,,, Albert C. Lardo, PhD, FACC, FAHA^_*,,,_*

^_* Department of Medicine, Division of Cardiology, Johns Hopkins University School of Medicine, Baltimore, Maryland
Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, Maryland
Department of Surgery, Johns Hopkins University School of Medicine, Baltimore, Maryland
Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, Maryland

^_* Reprint requests and correspondence: Dr. Albert C. Lardo, Johns Hopkins School of Medicine, Image Guided Cardiotherapy Laboratory, Division of Cardiology, 720 Rutland Avenue, 1042 Ross Building, Baltimore, Maryland 21205 (Email: al{at}jhmi.edu).

Objectives: We tested a circumferential mechanical dyssynchrony index (circumferential uniformity ratio estimate [CURE]; 0 to 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. MR-MT provides high quality mechanical activation data throughout the heart, and delayed enhancement cardiac magnetic resonance (DE-CMR) offers precise characterization of myocardial scar.

Methods: MR-MT was performed in 2 cohorts of heart failure patients with: 1) a CRT heart failure cohort (n = 20; left ventricular ejection fraction of 0.23 ± 0.057) to evaluate the role of MR-MT and DE-CMR prior to CRT; and 2) a multimodality cohort (n = 27; ejection fraction of 0.20 ± 0.066) to compare MR-MT and tissue Doppler imaging septal-lateral delay for assessment of mechanical dyssynchrony. MR-MT was also performed in 9 healthy control subjects.

Results: MR-MT showed that control subjects had highly synchronous contraction (CURE 0.96 ± 0.01), but tissue Doppler imaging indicated dyssynchrony in 44%. Using a cutoff of <0.75 for CURE based on receiver-operator characteristic analysis (area under the curve: 0.889), 56% of patients tested positive for mechanical dyssynchrony, and the MR-MT CURE predicted improved function class with 90% accuracy (positive and predictive values: 87%, 100%); adding DE-CMR (% total scar <15%) data improved accuracy further to 95% (positive and negative predictive values: 93%, 100%). The correlation between CURE and QRS duration was modest in all cardiomyopathy subjects (r = 0.58, p < 0.001). The multimodality cohort showed a 30% discordance rate between CURE and tissue Doppler imaging septal-lateral delay.

Conclusions: The MR-MT assessment of circumferential mechanical dyssynchrony predicts improvement in function class after CRT. The addition of scar imaging by DE-CMR further improves this predictive value.

Key Words: cardiac magnetic resonance • cardiac resynchronization therapy • biventricular • dyssynchrony • heart failure

Abbreviations and Acronyms   CMR = cardiac magnetic resonance   CRT = cardiac resynchronization therapy   CURE = circumferential uniformity ratio estimate   DE-CMR = delayed enhancement-cardiac magnetic resonance   HF = heart failure   MR-MT = magnetic resonance-myocardial tagging   NPV = negative predictive value   PPV = positive predictive value   QRSd = QRS duration   ROC = receiver-operating characteristic   TDI = tissue Doppler imaging

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