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 symptomatic sick sinus syndrome when bradyarrhythmia has been demonstrated to account for symptoms. 1, 2

Diagnostic Confirmation

• Sick sinus syndrome (SSS) encompasses a group of disorders characterized by the heart's inability to perform its pacemaker function properly, often related to age-dependent, degenerative fibrosis of the sinus nodal tissue 3
• Diagnosis is made by electrocardiographic identification of the arrhythmia in conjunction with symptoms related to end-organ hypoperfusion 4
• Approximately 50% of patients develop alternating bradycardia and tachycardia (tachy-brady syndrome) 4

Treatment Algorithm

First-Line Treatment: Permanent Pacemaker Implantation

• Permanent pacemaker therapy is highly effective in patients with sinus node dysfunction when bradyarrhythmia causes symptoms 1
• Pacemaker selection considerations:
  • Physiological pacing (atrial or dual-chamber) is superior to VVI pacing 1, 2
  • Atrial-based rate-responsive pacing is preferred to minimize exertion-related symptoms 1
  • Dual-chamber rate-responsive pacemakers (DDDR) are recommended over single-lead atrial pacing (AAIR) 5
  • DDDR pacing is associated with lower incidence of paroxysmal atrial fibrillation and reduced risk of pacemaker reoperation compared to AAIR 5

Important Benefits of Permanent Pacing

• Effectively relieves symptoms and 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 2, 6

Medication Management

Elimination of Bradycardia-Promoting Medications

• Identify and discontinue medications that may exacerbate or unmask underlying susceptibility to bradycardia 1
• Common offending agents include:
  • Cardiac glycosides 1
  • Beta-adrenergic blockers 1
  • Calcium channel blockers 1
  • Membrane-active antiarrhythmic agents (especially sotalol and amiodarone) 1
  • Other bradycardia-promoting sympatholytic agents used for hypertension 1

Caution with Antiarrhythmic Medications

• Flecainide should be used only with extreme caution in patients with sick sinus syndrome as it may cause sinus bradycardia, sinus pause, or sinus arrest 7
• Propafenone experience in patients with sick sinus node syndrome is limited and these patients should not be treated with propafenone 8

Emerging Pharmacological Options

• Cilostazol may be considered in select cases to potentially avoid or delay permanent pacemaker implantation by increasing heart rate 9
• In a retrospective case-control study, cilostazol reduced the 6-month pacemaker implantation rate (20.4% vs. 55.8%) in patients with SSS 9

Clinical Considerations and Caveats

• Despite adequate pacing, syncope recurs in approximately 20% of sick sinus syndrome patients during long-term follow-up due to associated vasodepressor reflex mechanisms 1, 2
• The presence of structural heart disease or left ventricular dysfunction may impact treatment decisions 2
• Consider biventricular pacing in patients with depressed left ventricular ejection fraction, heart failure, and prolonged QRS duration 2
• For patients with tachy-brady syndrome, adequate pacing of the heart is effective for controlling tachyarrhythmia attacks 10
• Percutaneous cardiac ablative techniques may be considered for atrial tachyarrhythmia control in patients with tachy-brady syndrome 1, 2