Prognostic Value of Different Thresholds for Myocardial Scar Quantification on Cardiac MRI Late Gadolinium Enhancement Images in Patients Receiving Implantable Cardioverter Defibrillators

Tamar Shalmon; Faisal Mhd Dib Hamad; Laura Jimenez-Juan; Anish Kirpalani; Camila M Urzua Fresno; Luciano Folador; Nigel S Tan; Sheldon M Singh; Yin Ge; Paul Dorian; João A C Lima; Kathy C K Wong; Djeven P Deva; Andrew T Yan

doi:10.1148/ryct.210247

Prognostic Value of Different Thresholds for Myocardial Scar Quantification on Cardiac MRI Late Gadolinium Enhancement Images in Patients Receiving Implantable Cardioverter Defibrillators

Radiol Cardiothorac Imaging. 2023 May 25;5(3):e210247. doi: 10.1148/ryct.210247. eCollection 2023 Jun.

Affiliation

¹ From the Department of Medical Imaging (T.S., F.M.D.H., L.J.J., A.K., C.M.U.F., L.F., D.P.D., A.T.Y.), Li Ka Shing Knowledge Institute (A.K., P.D., D.P.D., A.T.Y.), and Division of Cardiology (N.S.T., Y.G., P.D., A.T.Y.), Unity Health Toronto, University of Toronto, St Michael's Hospital, 30 Bond St, Toronto, ON, Canada M5B 1W8; Division of Cardiology, Sunnybrook Health Sciences Centre, University of Toronto, Toronto, Canada (S.M.S.); Division of Cardiology and The Russell H. Morgan Department of Radiology and Radiological Sciences, Johns Hopkins University School of Medicine, Baltimore, Md (J.A.C.L.); and Department of Radiology, The University of Hong Kong, Hong Kong (K.C.K.W.).

Abstract

Purpose: To compare the predictive value of different myocardial scar quantification thresholds using cardiac MRI for appropriate implantable cardioverter defibrillator (ICD) shock and mortality.

Materials and methods: In this retrospective, two-center observational cohort study, patients with ischemic or nonischemic cardiomyopathy underwent cardiac MRI prior to ICD implantation. Late gadolinium enhancement (LGE) was first determined visually and then quantified by blinded cardiac MRI readers using different SDs above the mean signal of normal myocardium, full-width half-maximum, and manual thresholding. The intermediate signal "gray zone" was calculated as the differences between different SDs.

Results: Among 374 consecutive eligible patients (mean age, 61 years ± 13 [SD]; mean left ventricular ejection fraction, 32% ± 14; secondary prevention, 62.7%), those with LGE had a higher rate of appropriate ICD shock or death than those without (37.5% vs 26.6%, log-rank P = .04) over a median follow-up of 61 months. In multivariable analysis, none of the thresholds for quantifying scar was a significant predictor of mortality or appropriate ICD shock, while the extent of gray zone was an independent predictor (adjusted hazard ratio per 1 g = 1.025; 95% CI: 1.008, 1.043; P = .005) regardless of the presence or absence of ischemic heart disease (P interaction = .57). Model discrimination was highest for the model incorporating the gray zone (between 2 SD and 4 SD).

Conclusion: Presence of LGE was associated with a higher rate of appropriate ICD shock or death. Although none of the scar quantification techniques predicted outcomes, the gray zone both in infarct and nonischemic scar was an independent predictor and may refine risk stratification.Keywords: MRI, Scar Quantification, Implantable Cardioverter Defibrillator, Sudden Cardiac Death Supplemental material is available for this article. © RSNA, 2023.

Keywords: Implantable Cardioverter Defibrillator; MRI; Scar Quantification; Sudden Cardiac Death.