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

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. [Figure: see text]