Treatment for Sick Sinus Syndrome
Permanent pacemaker implantation is the definitive treatment for sick sinus syndrome when symptomatic bradycardia has been documented, with dual-chamber rate-responsive (DDDR) pacing being the preferred mode. 1, 2
Initial Management: Eliminate Reversible Causes
Before proceeding to permanent pacing, you must identify and eliminate medications that exacerbate bradycardia 1, 2:
- Discontinue beta-blockers (contraindicated in sick sinus syndrome) 2
- Discontinue non-dihydropyridine calcium channel blockers (verapamil, diltiazem) 2
- Review and stop cardiac glycosides, membrane-active antiarrhythmics, and Class IC agents if possible 2, 3
- Exclude sleep apnea-hypopnea syndrome in patients with obesity and daytime tiredness, as nCPAP may resolve bradyarrhythmias and eliminate the need for pacing 4
Definitive Treatment: Permanent Pacemaker
Indications for Pacing
Pacemaker implantation is indicated when 1:
- Documented correlation between symptoms (syncope, presyncope, dizziness) and bradycardia on ECG monitoring 1
- Sinus pauses >3 seconds with symptoms 1
- Age-inappropriate bradycardia causing symptoms (definition varies by age) 1
- Symptomatic chronotropic incompetence 1
Optimal Pacing Mode
Dual-chamber rate-responsive pacing (DDDR) is the preferred mode for the following reasons 1, 2:
- Reduces risk of atrial fibrillation compared to ventricular pacing 1
- Reduces risk of stroke 1
- Improves quality of life and prevents pacemaker syndrome 1, 2
- Minimizes exertion-related symptoms through rate-responsive function 2
Programming considerations 1:
- Activate mode-switch algorithm to handle paroxysmal atrial arrhythmias
- Program rate-response function appropriately, especially in young and physically active patients
- Minimize percentage of ventricular pacing at each follow-up
Alternative Pacing Options
- Atrial-based minimal ventricular pacing modes are recommended as alternatives to conventional DDDR 2
- Single-chamber atrial pacing (AAI) may be considered in select patients without AV conduction disease 1
- Biventricular pacing should be considered if the patient has depressed left ventricular ejection fraction, heart failure symptoms, and prolonged QRS duration 1, 2
Management of Tachy-Brady Syndrome
For patients with the bradycardia-tachycardia variant of sick sinus syndrome 1, 2, 5:
- Permanent pacemaker first to protect against bradycardia 2, 5
- Then address tachyarrhythmias:
- Catheter ablation is first-line for paroxysmal AV nodal reciprocating tachycardia, AV reciprocating tachycardia, or typical atrial flutter 1, 2
- Individualize treatment for atrial fibrillation or atypical left atrial flutter 1, 2
- Antiarrhythmic drugs may be used after pacemaker placement to control tachyarrhythmias without risk of symptomatic bradycardia 1
Temporary/Emergency Management
While awaiting permanent pacemaker implantation 2:
- Continuous ECG monitoring for symptomatic patients 2
- Atropine for temporary emergency management of symptomatic bradycardia 2
- Isoproterenol infusion for refractory symptomatic bradycardia 2
Expected Outcomes and Limitations
Symptomatic improvement occurs in approximately 95% of patients after pacemaker implantation 6, 7:
- Syncope is eliminated or reduced in most patients 6, 7
- Quality of life improves significantly 1, 2
- Mortality is not reduced by pacing; survival depends primarily on underlying cardiac disease 2, 6
- Syncope recurs in ~20% of patients during long-term follow-up due to coexisting vasodepressor reflex mechanisms 2, 5
Critical Pitfalls to Avoid
- Do not implant a VVI pacemaker in patients with sinus node disease, as this increases risk of atrial fibrillation, stroke, and pacemaker syndrome 1
- Do not use beta-blockers or non-dihydropyridine calcium channel blockers without a functioning pacemaker 2, 3
- Do not attribute all syncope to bradycardia after pacemaker placement; evaluate for orthostatic hypotension and vasovagal mechanisms 5
- Screen for sleep apnea before pacing in obese patients with daytime somnolence 4