['Characterization of sudden cardiac death (SCD) risk remains a challenge in the application of implantable cardioverter-defibrillator (ICD) therapy. Late gadolinium enhancement cardiac MRI (LGE-CMR) can accurately identify myocardial scar. We performed a retrospective, single-center observational study to evaluate the association between the extent and distribution of left ventricular scar, quantified using LGE-CMR, and the burden of ventricular arrhythmias in patients with coronary artery disease and ICDs.', 'All patients included (2006 to 2009) had undergone LGE-CMR before ICD implantation. Scar (defined as myocardium with a signal intensity ≥50% of the maximum in scar tissue) was characterized in terms of percent scar, scar surface area, and number of transmural left ventricular scar segments. The end point was appropriate ICD therapy. Sixty-four patients (mean age, 66±11 years; male sex, 51) were included. During 19±10 months follow-up, appropriate ICD therapy occurred in 19 (30%) patients. In Cox regression analyses, both percent scar (hazard ratio per 10%, 1.75; 95% CI, 1.09 to 2.81; P=0.02) and number of transmural scar segments (hazard ratio per segment, 1.40; 95% CI, 1.15 to 1.70; P=0.001) were significantly associated with the occurrence of appropriate ICD therapy.'] Is the extent of left ventricular scar quantified by late gadolinium enhancement MRI associated with spontaneous ventricular arrhythmias in patients with coronary artery disease and implantable cardioverter-defibrillators?