Epidemiology of Subclinical Atrial Fibrillation in Patients with Cardiac Implantable Electronic Devices: A Systematic Review and Meta-Regression.

Background: In recent years, attention to subclinical atrial fibrillation (SCAF), defined as the presence of atrial high-rate episodes (AHREs), in patients with cardiac implantable electronic devices (CIEDs), has gained much interest as a determinant of clinical AF and stroke risk. We aim to perform a systematic review and meta-regression of the available scientific evidence regarding the epidemiology of SCAF in patients receiving CIEDs. Methods: PubMed and EMBASE were searched for all studies documenting the prevalence of AHREs in patients (n=100 or more, <50% with history of AF) with CIEDs from inception to 20th August 2021, screened by two independent blind reviewers. This study was registered in PROSPERO: CRD42019106994. Results: Among the 2614 results initially retrieved, 54 studies were included, with a total of 72,784 patients. Meta-analysis of included studies showed a pooled prevalence of SCAF of 28.1% (95%CI: 24.3-32.1%), with high heterogeneity between studies (I-2=98%). A multivariable meta-regression was able to explain significant proportion of heterogeneity (R-2=61.9%, p<0.001), with age and follow-up time non-linearly, directly and independently associated with occurrence of SCAF. Older age, higher CHA(2)DS(2)-VASc score, history of AF, hypertension, CHF, and stroke/TIA were all associated with SCAF occurrence. Conclusions: In this systematic review and meta-regression analysis, SCAF was frequent among CIED recipients and was non-linearly associated with age and follow-up time. Older age, higher thromboembolic risk, and several cardiovascular comorbidities were associated with presence of SCAF.