P-wave and interatrial block: New predictor for atrial high rate episodes in patients with cardiac implantable electronic devices.

Background: The presence of interatrial block (IAB) is associated with the development of atrial fibrillation (AF). The aim of this study was to determine whether P-wave duration and presence of IAB before the implantation of a cardiac implantable electronic device (CIED) are associated with the presence of atrial high rate episodes (AHRE), during long-term follow-up.

Methods: 380 patients (57% men; 75 ± 10 years) were included. IAB was defined according to the International Consensus Criteria. AHRE was defined as an episode of atrial rate ≥225 beats/min with a minimum duration of 5 minutes.

Results: Documented paroxysmal AF before the implantation was present in 24% of the patients; 80% had hypertension and 32% structural heart disease. Mean P-wave duration was 123 ± 23 ms, and 39% of the patients had IAB (32% partial, 7% advanced). After a mean follow-up of 18 ± 12 months, 33% of the patients presented AHRE. Patients with AHRE had a P-wave duration significantly longer (130 ± 24 ms vs 119 ± 21 ms; P < 0.001) and a greater prevalence of IAB (53% vs 32%; P < 0.001). In a multivariate analysis, predictors of AHRE were: IAB (odds ratio [OR] 2.1; 95% confidence interval [CI] [1.3-3.4], P < 0.001) and previous paroxysmal AF (OR 2.6; 95% CI [1.5-4.3], P < 0.001). In patients without previous AF, the presence of IAB was also a significant predictor of AHRE (OR 3.1; 95% CI [1.8-5.5], P < 0.001).

Conclusions: IAB is a strong predictor of AHRE in patients with CIED. This finding is independent of the presence of prior paroxysmal AF.