RESUMEN
BACKGROUND: Atrial pacing (AP) can unmask or aggravate a preexisting interatrial block (IAB). The aim of our study was to determine whether AP is associated with the development of atrial high-rate episodes (AHRE) during follow-up. METHODS: Patients with dual-chamber cardiac implantable electronic devices (CIEDs), no previous documented atrial fibrillation, and with a 6-month minimum follow-up were included. In all patients, sinus and paced P-wave duration were measured. AHRE was defined as an episode of atrial rate ≥225 bpm with a minimum duration of 5 min, excluding those documented during the first 3 months after implantation. RESULTS: A total of 220 patients were included (75 ± 10 years, 61% male). After a mean follow-up of 59 ± 25 months, 46% of patients presented AHRE. Mean paced P-wave duration was significantly longer than the sinus P-wave duration (154 ± 27 vs. 115 ± 18 ms; p < .001). Sinus and paced P-waves were significantly longer in those who developed AHRE (sinus: 119 ± 20 vs. 112 ± 16; p = .006; paced: 161 ± 29 vs. 148 ± 23; p < .001). A paced P-wave ≥160 ms was the best predictor of AHRE, especially those lasting >24 h (odds ratio [OR] 4.2 [95% confidence interval (CI)] [1.6-11.4]; p = .004). CONCLUSIONS: AP significantly prolongs P-wave duration and is associated with further development of AHRE. A paced P-wave ≥160 ms is a strong predictor of AHRE and should be taken into consideration as a new definition of IAB in the presence of AP.