Right Atrial Strain as a Predictor of Atrial High-Rate Episodes in Pacemaker Patients: A Case-Control Pilot Study.

BACKGROUND: Atrial high-rate episodes (AHRE) detected by cardiac implantable electronic devices (CIEDs) represent subclinical atrial tachyarrhythmias that are strongly associated with an increased risk of progression to clinical atrial fibrillation (AF) and thromboembolic events. The underlying bi-atrial electrical and mechanical remodeling that precedes AHRE remains incompletely understood, particularly the role of right atrial (RA) function. OBJECTIVES: This study aimed to identify combined electrocardiographic (ECG) and echocardiographic predictors of device-detected AHRE in patients with dual-chamber pacemakers, with a specific focus on the incremental predictive value of RA strain assessed by two-dimensional speckle-tracking echocardiography (2D-STE). METHODS: A single-center, case-control study was conducted on a cohort of prospectively followed patients involving 60 adult patients with dual-chamber (DDD) pacemakers, divided into two groups: 30 patients with device-detected AHRE (AHRE⁺) and 30 age- and sex-matched controls without AHRE (AHRE⁻). All participants underwent detailed clinical evaluation, 12-lead ECG analysis (including P-wave duration and dispersion), and comprehensive transthoracic echocardiography, including 2D-STE for assessment of RA reservoir strain (RASr) and contractile strain (RASct). AHRE was defined as an atrial tachyarrhythmia ≥180 bpm lasting ≥6 min, verified by intracardiac electrograms. RESULTS: AHRE⁺ patients exhibited significantly prolonged P-wave duration (118 ± 14 ms vs 108 ± 12 ms; p = 0.04) and greater P-wave dispersion (42 ± 8 ms vs 36 ± 7 ms; p = 0.03). They also Echocardiographically, they demonstrated significantly higher left atrial volume index (LAVI) (34.2 ± 6.8 vs 28.5 ± 5.2 mL/m²; p = 0.012) and right atrial volume index (RAVI) (26.4 ± 5.1 vs 22.7 ± 4.3 mL/m²; p = 0.028), RA function was markedly impaired in the AHRE⁺ group, with reduced right atrial reservoir and contractile strain (RASr 15.8 % vs 25.9 %, p = 0.041; RASct -2.0 % vs -11.6 %, p = 0.012). Multivariate analysis identified four independent predictors of AHRE: RASr < 20 % (OR 3.8; 95 % CI 1.7-8.4; p < 0.001), LAVI ≥ 34 mL/m² (OR 3.1; 95 % CI 1.5-6.2; p = 0.003), P-wave dispersion ≥ 40 ms (OR 2.6; 95 % CI 1.2-5.8; p = 0.008), Ventricular pacing > 90 % (OR 2.1; 95 % CI 1.0-4.4; p = 0.032). The model achieved strong discrimination (AUC = 0.84; 95 % CI 0.76-0.92) and good calibration (Hosmer-Lemeshow p = 0.47). CONCLUSIONS: The occurrence of AHRE in DDD pacemaker patients is independently associated with a combination of electrical and mechanical bi-atrial remodeling. Impaired right atrial strain (RASr < 20%) provides significant incremental predictive value beyond conventional metrics like P-wave dispersion and left atrial enlargement. Integrating RA strain into routine echocardiographic assessment may serve as a powerful, early marker for risk stratification of atrial arrhythmogenic remodeling in this high-risk population.