Automated electrocardiographic quantification of myocardial scar in patients undergoing primary prevention implantable cardioverter-defibrillator implantation: Association with mortality and subsequent appropriate and inappropriate therapies

Background: Myocardial scarring from infarction or nonischemic fibrosis forms an arrhythmogenic substrate. The Selvester QRS score has been developed to estimate myocardial scar from the 12-lead electrocardiogram. Objective: We aimed to assess the value of an automated version of the Selvester QRS score for the prediction of implantable cardioverter-defibrillator (ICD) therapy and death in patients undergoing primary prevention ICD implantation. Methods: Unselected patients undergoing primary prevention ICD implantation were included in this retrospective, observational, multicenter study. The QRS score was calculated automatically from a digital standard preimplantation 12-lead electrocardiogram and was correlated to the occurrence of death and appropriate and inappropriate shocks during follow-up. Analyses were performed in groups defined by QRS duration < 130 ms vs ≥ 130 ms. Results: Overall, 1047 patients (872 [83%] men; median age 64 years IQR [55-71]) with ischemic (648, 62%) or nonischemic (399, 38%) cardiomyopathy were included. The median QRS duration was 123 ms (interquartile range [IQR] 111–157 ms), and the median QRS score was 5 (IQR 2–8). The QRS duration was <130 ms in 59% and ≥130 ms in 41%. During a median follow-up of 45 months (IQR 24–72 months), a QRS score of ≥5 was independently associated with a significantly higher risk of mortality (hazard ratio [HR] 1.67; 95% confidence interval [CI] 1.05–2.66; P =.031) and appropriate (HR 1.83; 95% CI 1.07–3.14; P =.028) and inappropriate (HR 2.32; 95% CI 1.04–5.17; P =.039) shocks in patients with QRS duration ≥ 130 ms. No association of the QRS score and outcome was observed in patients with QRS duration < 130 ms (P >.05). Conclusion: The automatically calculated Selvester QRS score, an indicator of myocardial scar burden, predicts mortality and appropriate and inappropriate shocks in patients undergoing primary prevention ICD implantation with a prolonged QRS duration.