Atrial high rate episodes in patients with cardiac implantable electronic devices: implications for clinical outcomes

Background: Atrial high rate episodes (AHREs) detected by cardiac implantable electronic devices (CIEDs) are associated with an increased risk of stroke. However, the impact of AHRE on improving stroke risk stratification scheme remains uncertain. Objective: The purpose of this study was to assess the impact of AHRE on prognosis in relation with cardiovascular events and risk stratification. Methods: A total of 856 consecutive patients who had dual-chamber CIEDs implanted were retrospectively analyzed. To detect AHREs, they were monitored for 6 months after CIEDs’ implantation and were followed for a mean of 4.0 years for clinical outcomes such as thromboembolism or death. Results: Overall, 125 (14.6%) of patients developed AHREs within the first 6 months (median age 72.0 years, 39.3% female). Patients with AHREs had a high rate of thromboembolism (2.6%/year) and mortality (3.0%/year). On multivariate analysis, AHRE was significantly associated with increased risk of thromboembolism [hazard ratio (HR) 3.40; 95% confidence interval (CI) 1.38–8.37, P = 0.01] and death (HR 3.47; 95% CI 1.51–7.95; P < 0.01). The predictive abilities of the CHADS2 and CHA2DS2-VASc scores were modest, with no significant improvements by adding AHRE to those scores. However, the integrated discrimination improvement and net reclassification improvement showed that the addition of AHRE to the CHADS2 and CHA2DS2-VASc scores statistically improved their predictive ability for the composite outcome. Conclusions: AHRE was an independent factor associated with increased risk of clinical outcomes. The addition of AHRE to the clinical risk scores significantly improved discrimination for thromboembolism or death.