Practice Update: Cardiology

EDITOR’S PICKS 6

Significance of Subclinical Atrial Fibrillation in Older Patients Circulation Take-home message • This study followed 256 patients aged 74±6 years with implanted subcutaneous electrocardiographic monitors for 16.3±3.8 months to evaluate subclinical atrial fibrillation (SCAF). SCAF ≥5 minutes was detected in 90 patients. Older age, higher blood pressure, and larger left atrial dimension were baseline predictors of SCAF. There was no difference in SCAF occurrence between patients with or without a history of TIA, stroke, or systemic embolism. • These findings demonstrate the frequent detection of SCAF in older patients; however, the clinical significance is not clear at this time. Abstract BACKGROUND Long-term continuous electrocardiographic monitoring shows a substantial prevalence of asymptomatic, subclinical atrial fibril- lation (SCAF) in patients with pacemakers and patients with cryptogenic stroke. It is unknown if SCAF is also common in other patients without these conditions. METHODS We implanted sub-cutaneous electrocardiographic monitors (St. Jude CONFIRM-AF) in patients ≥ 65 years attending cardiovascular or neurology outpatient clinics if they had no history of atrial fibrillation (AF) but did have any of: CHA2DS2-VASc score of ≥ 2, sleep apnea, or body mass index > 30. Eligibility also required either left atrial enlargement (≥ 4.4 cm or volume ≥ 58 mL) or increased serum NT-ProBNP (≥290 pg/mL). Patients were monitored for SCAF lasting ≥ 5 minutes.

COMMENT By T. Jared Bunch MD A trial fibrillation (AF) continues to increase in incidence worldwide as populations age and people live longer with coexistent cardiovascular diseases. 1 Tominimize AF-related comorbidities, early recognition andmanagement of the arrhythmia is advocated. AF diagnosis has been in a constant state of evolu- tion as technologies have advanced to allow long-termmonitoring through multiple types of cardiac implantable electronic devices (CIED) andwearable devices. CIEDdetection of AF can significantly precede clinical symptoms and diagnosis of the arrhythmia. Such detection opportunities provide enthusiasm that very early treat- ment of the arrhythmia may alter risks of stroke, heart failure, and death, and perhaps alter that natural history of AF. AF management is based upon the identification of coexisting risk factors for adverse outcomes such as aging, diabetes, heart failure, stroke, vascular disease, etc. These same risk factors that predict AF outcomes also strongly predict its incidence. In a study of 100,000 patients without AF followed on average for 9 years, with each additional risk factor the odds of AF increased significantly from 3.05, 12.9, 22.8, 34.0, and 48.0, respectively. 2 In another study of patients with a cryptogenic stroke, AF was detected with a CIED in 12.4% at 1 year. 3 As AF risk factors are strongly associated with AF incidence, higher-risk patients may benefit from implantation of a implantable loop recorder (ILR) to prompt very early AF diagnosis. Healey and colleagues, on behalf of the ASSERT II trial inves- tigators, 4 in a study of 256 elderly patients (≥65 years) sought to determine the incidence of subclinical AF in higher-risk patients using ILRs. Higher risk was determined if the patient had a CHA2DS2-VASc score of ≥2 or left atrial enlargement with obstructive sleep apnea or a body mass index >30, or an elevated NT-ProBNP ≥290 pg/mL. In this study, 48% of the

RESULTS 256 patients were followed for 16.3±3.8 months. Baseline age was 74±6 years, mean CHA2DS2-VASc score was 4.1±1.4, left atrial diameter

averaged 4.7±0.8 cm, and 48% had a prior stroke, transient ischemic attack or systemic embolism. SCAF ≥ 5 minutes was detected in 90 patients (detection rate 34.4% per year; 95% confidence interval [CI], 27.7-42.3%). Baseline predictors of SCAF were increased age (HR per decade: 1.55; 1.11-2.15), left atrial dimension (HR per centimeter diameter: 1.43; 1.09-1.86), blood pressure (HR per 10 mmHg 0.87; 0.78-0.98), but not prior stroke. The rate of occurrence of SCAF in those with a history of prior stroke, systemic embolism or TIA was 39.4% per year versus 30.3% per year with- out (p=0.32). The cumulative SCAF detection rate was higher (51.9% per year) in those with left atrial volume above the median value of 73.5 mL. CONCLUSIONS SCAF is frequently detected by continuous electrocardiographic monitor- ing in older patients without prior history of AF who are attending outpatient cardiology and neurology clinics. Its clinical significance is unclear. Subclinical atrial fibrillation in older patients. Circulation 2017 Aug 04;[EPub Ahead of Print], JS Healey, M Alings, AC Ha, et al. www.practiceupdate.com/c/56679

PRACTICEUPDATE CARDIOLOGY