What is the initial treatment for sick sinus syndrome?

Initial Treatment for Sick Sinus Syndrome

Permanent cardiac pacemaker implantation is the definitive initial treatment for sick sinus syndrome when bradyarrhythmia has been demonstrated to account for symptoms. 1, 2

Diagnostic Considerations

• Sick sinus syndrome (SSS) encompasses a group of disorders characterized by the heart's inability to perform its pacemaker function properly 3
• Often related to age-dependent, progressive, degenerative fibrosis of the sinus nodal tissue and surrounding atrial myocardium 3
• Predominantly affects older adults, typically in their 70s or 80s 3
• May present as:
  • Sinus bradycardia 4
  • Sinoatrial block/sinus arrest 4
  • Tachy-brady syndrome (alternating bradycardia and tachycardia) - occurs in at least 50% of patients 3, 4

Treatment Algorithm

Step 1: Eliminate Exacerbating Medications

• Identify and discontinue medications that may exacerbate or unmask underlying bradycardia 1, 2:
  • Cardiac glycosides
  • Beta-adrenergic blockers
  • Calcium channel blockers
  • Membrane-active antiarrhythmic agents (especially sotalol and amiodarone)
  • Other bradycardia-promoting sympatholytic agents

Step 2: Permanent Pacemaker Implantation

• Indicated when bradyarrhythmia has been demonstrated to account for syncope 1, 2
• Highly effective in relieving symptoms but may not affect survival 1
• Pacemaker selection:
  • Physiological pacing (atrial or dual-chamber) is superior to VVI pacing 1, 2
  • Dual-chamber rate-responsive pacemakers (DDDR) are preferred over single-lead atrial pacing (AAIR) 2, 5
  • DDDR pacing is associated with:
    • Lower incidence of paroxysmal atrial fibrillation compared to AAIR pacing 5
    • Significantly lower risk of pacemaker reoperation (11.9% vs 22.1% with AAIR) 5
  • Rate-adaptive pacing is recommended to minimize exertion-related lightheadedness or syncope 1

Benefits of Permanent Pacing

• Excellent symptomatic improvement in patients with SSS 6
• Prevents recurrence of syncope 1, 6
• Lowers the risk of developing atrial fibrillation 1
• Improves quality of life by reducing symptoms of congestive heart failure, low cardiac output, and angina pectoris 1
• May improve survival compared to no treatment, though survival primarily depends on underlying cardiac disease 1, 6

Important Clinical Considerations

• Despite adequate pacing, syncope recurs in approximately 20% of patients during long-term follow-up due to associated vasodepressor reflex mechanisms 1, 3
• For the tachycardia component in tachy-brady syndrome:
  • Percutaneous cardiac ablative techniques may be considered for atrial tachyarrhythmia control 1, 3
  • Catheter ablation is the first-choice treatment for paroxysmal AV nodal reciprocating tachycardia, AV reciprocating tachycardia, or typical atrial flutter 2

Emerging Pharmacological Approaches

• While permanent pacing remains the standard of care, a recent retrospective study suggests cilostazol may be effective in some patients with SSS to potentially avoid or delay pacemaker implantation by increasing heart rate 7
• However, this approach requires further validation in prospective clinical trials before being recommended as an alternative to pacemaker implantation 7

Prognosis

• Prognosis is mainly determined by the presence or absence of coronary heart disease and/or heart failure 6
• Systemic embolization occurs more frequently in patients with tachy-brady syndrome than in those with pure bradyarrhythmias 6