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

Abstract

BackgroundThe 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 an existing scar. ObjectivesTo evaluate whether scar size is associated with VA in patients with an implantable cardioverter-defibrillator (ICD) and a CTO. MethodsIn this retrospective study we included patients with a CTO that received an ICD between 2005 and 2015. Scar size was estimated using the Selvester QRS score on a baseline 12‑lead ECG. The primary endpoint was any appropriate ICD therapy. ResultsOur study population comprised 148 CTO patients with a median scar size at baseline of 18% (IQR, 9–27%). Patients with a scar size ≥18% more often had a CTO located in the left anterior descending artery and a higher proportion of poor left ventricular function (<35%) and infarct-related CTO compared to patients with a smaller scar 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 scar in comparison to those with a smaller or no scar (36% versus 19%, P = 0.04). Multivariable Cox regression analysis demonstrated that large scar and diabetes mellitus were independent factors associated with appropriate ICD therapy. ConclusionIn ICD recipients with an untreated CTO, a larger scar is an independent factor associated with an increased risk of VA.