Potential triggering of repetitive nonreentrant ventriculoatrial synchrony by loss of atrial capture.

BACKGROUND: Data on the factors that trigger repetitive nonreentrant ventriculoatrial synchrony (RNRVAS) are limited. We hypothesize that loss of atrial capture may trigger RNRVAS. We aimed to use an atrial threshold test to observe the development of RNRVAS upon loss of atrial capture in patients with implantable cardiac electronic devices (CIED). METHODS: Patients with DDD mode CIEDs [177 patients, 67.5 ± 14.8 (70) years; 70 women] were included. Atrial threshold test was done in DDD mode at a rate at least 10 beats above the basal heart rate, with an AV delay of 300 ms (range 250-350). A multivariable logistic regression model was used to assess the independent predictors of RNRVAS. RESULTS: RNRVAS was observed in 69 of the 177 patients (39.0%) during atrial threshold test. In patients with VA conduction, incidence of RNRVAS increased to 76.7%. In univariate analysis, younger age (p = .038) and the presence of VA conduction (p < .001) were associated with an increased risk of RNRVAS, whereas complete AV block or any AV node conduction defect (p < .001) and the ventricular pacing ratio (p = .001) were inversely related to the risk of RNRVAS occurrence after loss of atrial capture. In multivariate analysis complete AV block (p = .009) and ventricular pacing ratio (p = .029) appeared as independent factors inversely related to the risk of RNRVAS development. CONCLUSION: In this study, we demonstrated that loss of atrial capture results in RNRVAS in one-third of patients with a CIED in DDD mode, and in three-fourths of those with VA conduction under certain predisposing CIED settings.