Potential triggering of Repetitive Nonreentrant Ventriculoatrial Synchrony (RNRVAS) by loss of atrial capture.

Background Data on the factors that trigger repetitive non-reentrant 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 the 69 of 177 patients (39.0%). In patients with VA conduction, incidence of RNRVAS increased to 76.7%. The patients with RNRVAS were younger than those without RNRVAS ( P = .038). History of complete AV block, any AV node conduction defect ( P < .001) and ventricular pacing ratio ( P = .001) were significantly higher and VA conduction ( P < .001) significantly less in patients without RNRVAS than in patients with RNRVAS. History of complete AV block ( P = .009) and ventricular pacing ratio ( P = .029) appeared as independent factors indicating decreased 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.