Introduction The incidence of new-onset atrial high-rate episode (AHRE) is higher among patients with cardiac implantable electronic devices (CIEDs) than in the general population. We sought to elucidate the clinical factors including P-wave dispersion (PWD) in sinus rhythm associated with AHRE in CIED patients. Methods and results One hundred one patients with newly implanted CIEDs from 2010 to 2014 at our institute were included. PWD was measured at the time of device implantation via a body-surface electrocardiogram. AHRE was defined as any episode of sustained atrial tachyarrhythmia (>170 bpm) recorded in the device’s memory. Patients were divided into an AHRE group (n=34) and non-AHRE group (n=67) in accordance with the presence or absence of AHRE within one year of device implantation and compared. The mean age was 75 ± 11 years old. A greater incidence of sick sinus syndrome (p=0.05) and longer PWD (62.6 ± 13.1 vs. 38.2 ± 13.9 ms; p<0.0001) were apparent in the AHRE group. Multivariate analysis revealed that PWD was an independent predicting factor for new-onset AHRE (odds ratio: 1.11; 95% confidence interval: 1.06–1.17; p<0.0001). In the logistic regression analysis, the receiver-operating characteristic curve (area under the curve: 0.90; p<0.001) suggested the best cutoff value for PWD was 48 mm, achieving a sensitivity of 73.8% and specificity of 77.9%. Conclusion PWD is a simple but feasible predictor for new-onset AHRE in patients with cardiac implantable electronic devices.

Background: Local impedance (LI) can indirectly measure catheter contact and tissue temperature during radiofrequency catheter ablation (RFCA). However, data on the effects of catheter contact angle on LI parameters are scarce. This study aimed to evaluate the influence of catheter contact angle on LI changes and lesion size with 2 different LI-sensing catheters in a porcine experimental study. Methods: Lesions were created by the INTELLANAV MiFi™ OI (MiFi) and the INTELLANAV STABLEPOINT™ (STABLEPOINT). RFCA was performed with 30 watts and a duration of 30 seconds. The CF (0, 5, 10, 20, and 30 g) and catheter contact angle (30°, 45°, and 90°) were changed in each set (n=8 each). The LI rise, LI drop, and lesion size were evaluated. Results: The LI rise increased as CF increased. There was no angular dependence with the LI rise under all CFs in the MiFi. On the other hand, the LI rise at 90° was lower than at 30° under 5 and 10 g of CF in STABLEPOINT. The LI drop increased as CF increased. Regarding the difference in catheter contact angles, the LI drop at 90° was lower than that at 30° for both catheters. The maximum lesion widths and surface widths were smaller at 90° than at 30°, whereas there were no differences in lesion depths. Conclusion: The LI drop and lesion widths at 90° were significantly smaller than those at 30°, although the lesion depths were not different among the 3 angles for the MiFi and STABLEPOINT.