Identifying At‐Risk Patients for Sustained Atrial High‐Rate Episodes Using the C ₂ HEST Score: The West Birmingham Atrial Fibrillation Project

Background Sustained atrial high-rate episodes (SAHREs) among individuals with a cardiac implantable electronic device are associated with an increased risk of adverse outcomes. Risk stratification for the development of SAHREs has never been investigated. We aimed to assess the performance of the C₂HEST (coronary artery disease or chronic obstructive pulmonary disease [1 point each], hypertension [1 point], elderly [age ≥75 years, 2 points], systolic heart failure [2 points], thyroid disease [1 point]) score in predicting SAHREs in patients with cardiac implantable electronic devices without atrial fibrillation. Methods and Results Five Hundred consecutive patients with cardiac implantable electronic devices in the West Birmingham Atrial Fibrillation Project in the United Kingdom were followed since the procedure to observe the development of SAHREs, defined by atrial high-rate episodes lasting >24 hours. Risk factors and incidence of SAHREs were analyzed. The predictive value of the C₂HEST score for SAHRE prediction was evaluated. Over a mean follow-up of 53.1 months, 44 (8.8%) patients developed SAHREs. SAHREs were associated with higher all-cause mortality (<i>P</i><0.001) and ischemic stroke (<i>P</i>=0.001). Age and heart failure were associated with SAHRE occurrence. The incidence of SAHREs increased by the C₂HEST score (39% higher risk per point increase). Among patients with a C₂HEST score ≥4, the incidence of SAHREs was 3.62% per year (95% CI, 2.14-5.16). The C₂HEST score had moderate predictive capability (area under the curve, 0.73; 95% CI, 0.64-0.81) and discriminative ability (log-rank <i>P</i>=0.003), which was better than other clinical scores (CHA₂DS₂-VASc, CHADS₂, HATCH). Conclusions The C₂HEST score predicted SAHRE incidence in patients without atrial fibrillation who had an cardiac implantable electronic device, with the highest risk seen in patients with a C₂HEST score ≥4 The benefit of using the C₂HEST score in clinical practice in this patient population needs further investigation.