What is the management of sick sinus syndrome?

Management of Sick Sinus Syndrome

Permanent pacemaker implantation is the definitive treatment for symptomatic sick sinus syndrome, with dual-chamber rate-adaptive pacing (DDDR) preferred over single-chamber pacing. 1

Diagnosis and Initial Assessment

• Diagnostic criteria:

  • Electrocardiographic evidence of sinus node dysfunction (bradycardia, sinus pauses, sinoatrial block)
  • Correlation between symptoms and bradyarrhythmias
  • Extended monitoring often required (24-hour Holter, event monitoring, implantable loop recorder) 1

• Common presentations:

  • Syncope or near-syncope (occurs in ~50% of patients)
  • Dizziness, fatigue, palpitations
  • Tachy-brady syndrome (alternating bradycardia and tachycardia) in at least 50% of patients 2

Acute Management of Symptomatic Bradycardia

1. For hemodynamically unstable patients:

   • Initiate temporary cardiac pacing promptly 1
   • Pharmacologic therapy as bridge to pacing:
     • Atropine 0.5-1.0 mg IV (first-line) 3, 1
     • Isoproterenol infusion if atropine is ineffective 3

   Caution: Atropine may cause paradoxical block or sinus arrest in heart transplant patients 3

2. For stable patients with symptoms:

   • Discontinue or adjust bradycardia-inducing medications
   • Consider permanent pacing evaluation

Definitive Management

Permanent Pacemaker Implantation

Class I indications for permanent pacing:

• Symptomatic bradycardia with documented correlation between symptoms and bradyarrhythmia 1
• Symptomatic chronotropic incompetence
• Symptomatic sinus bradycardia resulting from essential medications

Pacing mode selection:

• Preferred: Dual-chamber rate-adaptive pacing (DDDR) 1, 4

  • Associated with lower incidence of paroxysmal atrial fibrillation compared to single-lead atrial pacing 4
  • Reduces need for reoperation (11.9% vs 22.1% with AAIR) 4

• Avoid: Single-chamber ventricular pacing (VVI/VVIR) in SSS patients 1

  • Increases risk of pacemaker syndrome and atrial fibrillation

Medication Management

1. Review and adjust current medications:

   • Discontinue or reduce doses of bradycardia-inducing medications when possible:
     • Beta-blockers
     • Non-dihydropyridine calcium channel blockers
     • Antiarrhythmic drugs 1

2. Anticoagulation:

   • Consider in patients with SSS and atrial fibrillation due to increased thromboembolic risk (15.2% in unpaced SSS patients vs 1.3% in controls) 1
   • Follow standard atrial fibrillation anticoagulation guidelines

3. Theophylline:

   • May be considered in select patients who are not candidates for pacing
   • Can improve heart rate but less effective than pacemaker for preventing syncope 5
   • Limited evidence for long-term use

Special Considerations

1. Tachy-brady syndrome:

   • Requires management of both bradycardia and tachyarrhythmias
   • Pacemaker implantation may allow more aggressive antiarrhythmic therapy
   • Dual-chamber pacing helps preserve optimal atrioventricular coupling 6

2. Heart failure prevention:

   • Both pacemaker therapy and theophylline associated with lower incidence of heart failure compared to no treatment 5

3. Post-pacemaker follow-up:

   • Regular device checks to ensure proper function
   • Continued monitoring for development of atrial fibrillation
   • Adjustment of pacing parameters as needed

Prognosis

• Permanent pacing improves symptoms and quality of life 2
• Reduces incidence of syncope and heart failure 5
• Dual-chamber pacing associated with lower incidence of atrial fibrillation, thromboembolic events, and heart failure compared to ventricular pacing 7
• No significant difference in mortality between AAIR and DDDR pacing 4