Silent atrial fibrillation in patients with an implantable cardioverter defibrillator and coronary artery disease (INDICO AF) trial: study rationale and design

Cardiac Magnetic Resonance Imaging-Derived Left Atrial Characteristics in Relation to Atrial Fibrillation Detection in Patients With an Implantable Cardioverter-Defibrillator

Background Among patients with an implantable cardioverter-defibrillator, a high prevalence of atrial fibrillation (AF) is present. Identification of AF predictors in this patient group is of clinical importance to initiate appropriate preventive therapeutic measures to reduce the risk of AF-related complications. This study assesses whether cardiac magnetic resonance imaging-derived atrial characteristics are associated with AF development in patients with a dual-chamber implantable cardioverter-defibrillator or cardiac resynchronization therapy defibrillator, as detected by the cardiac implantable electronic device. Methods and Results This single-center retrospective study included 233 patients without documented AF history at the moment of device implantation (dual-chamber implantable cardioverter-defibrillator [63.5%] or cardiac resynchronization therapy defibrillator [36.5%]). All patients underwent cardiac magnetic resonance imaging before device implantation. Cardiac magnetic resonance-derived features of left atrial (LA) remodeling were evaluated in all patients. Detection of AF episodes was based on cardiac implantable electronic device interrogation. During a median follow-up of 6.1 years, a newly diagnosed AF episode was detected in 88 of the 233 (37.8%) patients with an ICD. In these patients, increased LA volumes and impaired LA function (LA emptying fraction and LA strain) were found as compared with patients without AF during follow-up. However, a significant association was only found in patients with dilated cardiomyopathy and not in patients with ischemic cardiomyopathy. Conclusions LA remodeling characteristics were associated with development of AF in patients with dilated cardiomyopathy but not patients with ischemic cardiomyopathy, suggesting different mechanisms of AF development in ischemic cardiomyopathy and dilated cardiomyopathy. Assessment of LA remodeling before device implantation might identify high-risk patients for AF.

Impact of Atrial Fibrillation on Hospitalization Outcomes of Heart Failure in Patients ≥ 60 Years with Implantable Cardioverter Defibrillator

The impact of atrial fibrillation (AF) on the hospitalization outcomes in patients ≥ 60 years of age with implantable cardioverter defibrillators (ICD) is not well studied. We queried the National Inpatient Sample database for all patients aged ≥ 60 who had a history of ICD placement, and were admitted with a primary diagnosis of heart failure (HF) during the years 2016-2017. Patients were stratified into 2 groups based on their history of AF. The primary outcome of the study was all-cause in-hospital mortality. Secondary outcomes included cardiogenic shock, myocardial infarction (MI), ventricular fibrillation (VF), stroke and acute kidney injury (AKI). The association between different age strata and outcomes was investigated. The hospitalization outcomes were modeled using logistic regression. A total of 178,045 patients were included, of whom 56.2% had AF. AF correlated with increased mortality (A-OR 1.22 (95% CI: 1.06-1.4), p=0.005), cardiogenic shock (A-OR 1.21 (95%CI: 1.08-1.36), p<0.001), AKI (A-OR 1.12 (95%CI: 1.06-1.17), p<0.001 and lower risk for MI (A-OR 0.79 (95% CI: 0.68-0.9), p<0.001. There was no correlation between AF and risk for VF or stroke. A significant correlation between AF and higher risk for mortality, cardiogenic shock and AKI was demonstrated in ages ≤ 75, ≤ 75, and ≤ 80 years, respectively. In contrast, a significant correlation between AF and lower risk for MI is only demonstrated at age > 70 years. We conclude that AF is an independent predictor for increased all-cause in-hospital mortality and cardiogenic shock. Such risk is influenced by age.