Predictors of syncope recurrence in reflex syncope patients with dual-chamber pacemakers with anti-reflex functionality

Abstract Background Dual-chamber pacemakers with anti-reflex syncope functionality have demonstrated efficacy in managing reflex syncope; however, a subset of patients still experiences recurrent episodes post-implantation. Furthermore, indications for pacemaker implantation in patients younger than 40 years and those with mixed-type responses to tilt-table testing remain uncertain due to limited evidence. This study aimed to evaluate the efficacy of dual-chamber pacemakers with anti-reflex syncope functionality and identify predictors of recurrent syncope in this specific patient population. Methods This study included patients with reflex syncope who had positive tilt-table test results and a clinical indication for dual-chamber pacemaker with anti-reflex syncope functionality. Patients were followed for 6 months post-implantation, with data collected on vital signs during tilt-table testing, pacemaker efficacy in preventing syncope recurrence, and an analysis of risk factor analysis for recurrent syncope. Results Among the cohort of 117 patients, 65% were female, with a mean age of 47.9 ± 15.1 years. Type 1 (mixed type) accounted for 25.6% of cases (30 patients), while type 2B was the most common, comprising 66.7% of the population. After 6 months, the recurrence rate was 12.8% (15/117). Cox multivariate regression analysis identified independent predictors of recurrence, including an asystole duration ≥ 13.5 seconds on tilt-table testing (hazard ratio [HR]: 20.2, 95% confidence interval [CI]: 2.009–202.307, p = 0.011), a pre-implantation syncope frequency ≥ 2.5 episodes (HR: 4.9, 95% CI: 1.089–22.536, p = 0.038), and a systolic blood pressure differential ≥ 102.5 mmHg between the end of the passive phase and syncope onset (HR: 5.1, 95% CI: 1.368–19.349, p = 0.015). In subgroup analysis, patients with mixed-type responses showed a significantly higher systolic blood pressure between the end of the passive phase and syncope onset differential in those with recurrence compared to non-recurrence (98.6 ± 15.6 mmHg vs. 80.2 ± 12.1 mmHg; p = 0.002). Conclusions Dual-chamber pacemakers with anti-reflex functionality effectively reduce recurrence rates in patients with reflex syncope, achieving a recurrence rate of 12.8% at 6 months. Independent predictors of recurrent syncope include an asystole duration ≥ 13.5 seconds, a pre-implantation episode frequency ≥ 2.5, and a systolic blood pressure differential ≥ 102.5 mmHg between the end of the passive phase and syncope onset, especially significant in patients with mixed-type responses. These findings support the use of pacemaker therapy in high-risk reflex syncope patients.Syncope Recurrence Characteristics  Kaplan-Meier Asystole time