Background - Myocardial scarring from infarction or nonischemic fibrosis forms an arrhythmogenic substrate. The modified Selvester QRS score has been extensively validated for estimating myocardial infarction scar size. This study was designed to evaluate the usefulness of the QRS score in predicting the prognosis of patients with implantable cardioverter defibrillator (ICD).

Methods - Sixty-six patients (male 52, age 53.9짹16.4 years) who underwent ICD implantation were evaluated. The 12-lead ECGs before ICD placement were analyzed with the modified Selvester QRS score criteria. We evaluated the number of appropriate ICD shock deliveries, cardiac death, non-fatal myocardial infarction and hospitalization due to heart failure within 1 year after ICD implantation.

Results - Mean QRS score was 5.0짹5.0 (range: 0-21). QRS score was inversely correlated with the left ventricular ejection fraction (R=-0.36, p=0.003), especially in ischemic cardiomyopathy patients. The endpoints were compared between low- (LS, score<5) and high- (HS, score���5) QRS score groups. The mean number of ICD shock deliveries was slightly higher in HS group (2.5짹3.8) than in the LS group (1.3짹2.5) (p=0.14). Incidence of combined cardiac events at 1 year was significantly higher in the HS group.

Conclusions - QRS-estimated scar size showed positive correlation with ICD shock deliveries and cardiac events. This quantification method could be used for risk stratifying tool in ICD patients.