From the Guidelines
In patients with complete heart block and a fixed split S1, permanent pacemaker implantation is recommended to alleviate symptoms and prevent adverse outcomes, as supported by the 2018 ACC/AHA/HRS guideline on the evaluation and management of patients with bradycardia and cardiac conduction delay 1.
Key Considerations
- The presence of a fixed split S1 in complete heart block indicates asynchronous contraction of the right and left ventricles due to AV dissociation.
- Management priorities include alleviating symptoms such as syncope, pre-syncope, or heart failure, and ensuring a reliable ventricular escape rhythm.
- The decision to implant a permanent pacemaker is guided by the presence of symptoms, the reliability of the ventricular escape rhythm, and the patient's overall clinical condition, as outlined in the guideline 1.
Clinical Evidence
- The 2018 ACC/AHA/HRS guideline highlights the importance of permanent pacing in patients with bradycardia and cardiac conduction delay, including those with complete heart block 1.
- The guideline also notes that certain clinical features, such as a deterioration or unreliability of the escape rate and an increased propensity to develop bradycardia-related ventricular arrhythmias, are high-risk markers for adverse outcomes in patients with congenital complete heart block 1.
Treatment Approach
- Permanent pacemaker implantation is the recommended treatment for symptomatic patients with complete heart block and a fixed split S1, as it can alleviate symptoms and prevent adverse outcomes 1.
- The choice of pacing mode and lead placement should be individualized based on the patient's underlying anatomy, surgical history, and clinical condition, with consideration given to the potential benefits of single-lead atrial-based pacing and epicardial lead placement in certain patient groups 1.
From the Research
Fixed Split S1 in Complete Heart Block
- In complete heart block, the choice of pacemaker type is crucial for patient outcomes.
- A study published in 2024 2 found that dual-chamber pacemakers are associated with a lower risk of mortality, heart failure, atrial fibrillation, and stroke compared to single-chamber pacemakers.
- Another study from 2005 3 found no significant difference in mortality rates between single-chamber and dual-chamber pacing in elderly patients with high-grade atrioventricular block.
- A case report from 2025 4 described the successful implantation of a dual-chamber leadless pacemaker via the right internal jugular vein in a 13-year-old patient with congenital complete heart block.
- Studies have also compared different pacing modes, such as DDD versus VVIR pacing 5 and DDIR versus DDDR pacing 6, with varying results.
Pacemaker Type and Patient Outcomes
- Dual-chamber pacemakers may offer benefits over single-chamber pacemakers in terms of reducing the risk of cardiovascular events 2.
- However, the choice of pacemaker type may not significantly impact mortality rates in elderly patients 3.
- The preservation of AV synchrony is an important consideration in pacemaker selection, with DDDR pacing showing better preservation of AV synchrony compared to DDIR pacing 6.
Pacing Modes and Patient Preferences
- Patients may have preferences for certain pacing modes, with some studies showing a preference for DDD pacing over VVIR pacing 5 and DDDR pacing over DDIR pacing 6.
- Quality of life scores may not differ significantly between different pacing modes, but patients may experience fewer somatic complaints with certain modes 6.