title: Assessment of myocardial scarring improves risk stratification in patients evaluated for cardiac defibrillator implantation.
abstract: OBJECTIVE
  We tested whether an assessment of myocardial scarring by cardiac magnetic resonance imaging (MRI) would improve risk stratification in patients evaluated for implantable cardioverter-defibrillator (ICD) implantation.
  
  
  BACKGROUND
  Current sudden cardiac death risk stratification emphasizes left ventricular ejection fraction (LVEF); however, most patients suffering sudden cardiac death have a preserved LVEF, and many with poor LVEF do not benefit from ICD prophylaxis.
  
  
  METHODS
  One hundred thirty-seven patients undergoing evaluation for possible ICD placement were prospectively enrolled and underwent cardiac MRI assessment of LVEF and scar. The pre-specified primary endpoint was death or appropriate ICD discharge for sustained ventricular tachyarrhythmia.
  
  
  RESULTS
  During a median follow-up of 24 months the primary endpoint occurred in 39 patients. Whereas the rate of adverse events steadily increased with decreasing LVEF, a sharp step-up was observed for scar size >5% of left ventricular mass (hazard ratio [HR]: 5.2; 95% confidence interval [CI]: 2.0 to 13.3). On multivariable Cox proportional hazards analysis, including LVEF and electrophysiological-study results, scar size (as a continuous variable or dichotomized at 5%) was an independent predictor of adverse outcome. Among patients with LVEF >30%, those with significant scarring (>5%) had higher risk than those with minimal or no (≤5%) scarring (HR: 6.3; 95% CI: 1.4 to 28.0). Those with LVEF >30% and significant scarring had risk similar to patients with LVEF ≤30% (p = 0.56). Among patients with LVEF ≤30%, those with significant scarring again had higher risk than those with minimal or no scarring (HR: 3.9; 95% CI: 1.2 to 13.1). Those with LVEF ≤30% and minimal scarring had risk similar to patients with LVEF >30% (p = 0.71).
  
  
  CONCLUSIONS
  Myocardial scarring detected by cardiac MRI is an independent predictor of adverse outcome in patients being considered for ICD placement. In patients with LVEF >30%, significant scarring (>5% LV) identifies a high-risk cohort similar in risk to those with LVEF ≤30%. Conversely, in patients with LVEF ≤30%, minimal or no scarring identifies a low-risk cohort similar to those with LVEF >30%.
authors: Duke Cardiovascular Magnetic Resonance Center, Duke University Medical Center, Durham, NC 27710, USA.
authors: Igor
authors: I
authors: Klem
authors: Jonathan W
authors: JW
authors: Weinsaft
authors: Tristram D
authors: TD
authors: Bahnson
authors: Don
authors: D
authors: Hegland
authors: Han W
authors: HW
authors: Kim
authors: Brenda
authors: B
authors: Hayes
authors: Michele A
authors: MA
authors: Parker
authors: Robert M
authors: RM
authors: Judd
authors: Raymond J
authors: RJ
authors: Kim
mesh_terms: D000328:Adult; D000368:Aged; D002423:Cause of Death; D002921:Cicatrix / Q000401:mortality / Q000473:pathology*; D016757:Death, Sudden, Cardiac / Q000453:epidemiology* / Q000473:pathology / Q000517:prevention & control; D017147:Defibrillators, Implantable; D004562:Electrocardiography; D023381:Endpoint Determination; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009206:Myocardium / Q000473:pathology*; D011379:Prognosis; D011446:Prospective Studies; D018570:Risk Assessment; D012815:Signal Processing, Computer-Assisted; D013318:Stroke Volume / Q000502:physiology*; D017180:Tachycardia, Ventricular / Q000401:mortality / Q000628:therapy*; D016896:Treatment Outcome; D018487:Ventricular Dysfunction, Left / Q000145:classification* / Q000401:mortality*