Introduction
Atrial fibrillation (AF), the most frequently encountered clinical cardiac arrhythmia, is associated with increased mortality and morbidity rates, largely due to thromboembolic complications and heart failure. Clinically detecting AF in the early phase is significantly important for avoiding such events but it is not always easy to do so, particularly in cases of asymptomatic AF. Although repeated electrocardiogram (ECG) recording or 24-hour ambulatory ECG monitoring are considered useful in detecting AF in the early phase, their sensitivities as such detection tools are totally limited.1 Recently, continuous rhythm monitoring with cardiac implantable electronic devices (CIEDs) has been used to diagnose brief episodes of arrhythmia including paroxysmal AF, which are recorded as atrial high-rate episodes (AHREs), particularly in the absence of clinical evidence of AF.1 By using this approach, new-onset atrial tachyarrhythmia/AF can be diagnosed earlier in patients with CIEDs in comparison with in those without CIEDs.
Previous reports have demonstrated that a prior history of heart failure, the presence of sick sinus syndrome (SSS), and the existence of a large left-atrial volume index (LAVI) were independent predictors for new-onset AHRE in patients with CIEDs.2 Furthermore, new-onset AHRE in patients with CIED has been linked to increased risks of stroke, systemic embolism, and worsening heart failure.3–5 As such, predicting new-onset AHRE following CIED implantation in patients without a history of AF is key to obtaining good patient outcomes.
P-wave dispersion (PWD), a well-known ECG parameter and predictor of AF, is defined as the difference between the maximum and the minimum P-wave durations detected on the body-surface 12-lead ECG.6,7Previous studies have suggested that longer PWD may be associated with AF occurrence following cardiac surgery, AF recurrence after conversion, and the appearance of the first AF episode or/and paroxysmal AF.7–10 Furthermore, it was reported that PWD could be a sensitive and specific ECG marker for the risk of AF occurrence with a cutoff value of 40 ms for the identification of patients with a history of paroxysmal AF.6 However, the connection between PWD and new-onset AHRE in patients with CIED remains largely unexamined. In the present study, we therefore sought to elucidate clinical factors including PWD that are associated with silent AHRE in CIED patient population.