Effect of infarct size on the risk of ventricular arrhythmias in patients with chronic total coronary occlusion

Abstract Funding Acknowledgements Type of funding sources: None. Background The presence of an untreated chronic total coronary occlusion (CTO) is associated with a higher risk of ventricular arrhythmias (VAs). This increased risk may be modulated by the presence of existing scar. We hypothesize that a larger scar size is associated with a higher risk of VA. Objectives To evaluate whether infarct size is associated with VA in patients with an implantable cardioverter-defibrillator (ICD) and an untreated CTO. Methods In this retrospective study we included patients with an untreated CTO that received an ICD between 2005 and 2014. Infarct size was estimated using the Selvester QRS score on a baseline 12-lead ECG. The primary endpoint was any appropriate ICD therapy. Results Our study population comprised 148 patients (mean age at implantation 64 ± 10 years, 87% men) with an ICD and an untreated CTO. The median infarct size at baseline was 18% (IQR, 9-27%). Patients with a larger scar size (≥18%) more often had a CTO location in the LAD, higher proportion of LVEF <35%, and less hypertension and hypercholesterolemia compared to patients with a smaller infarct size (<18%). During a median follow-up of 35 months (interquartile range [IQR], 8-60 months), 42 patients (28%) received appropriate ICD therapy. The cumulative 5-year event rate was higher in the patients with a large infarct size (≥18%) in comparison to those with a smaller infarct size (<18%) (36% versus 19%, logrank P = 0.038, Figure). Multivariable Cox regression analysis demonstrated that a larger infarct size (≥18%) and a secondary prevention indication were independent factors associated with appropriate ICD therapy. The adjusted hazard ratio of large infarct size (≥18%) for appropriate ICD therapy was 2.34 (95% CI 1.20-4.58, p=0.01). Conclusion In ICD recipients with an untreated CTO, a larger scar size is an independent factor associated with an increased risk of VA.