What is the management of sick sinus syndrome?

Management of Sick Sinus Syndrome

Definitive Treatment

Permanent pacemaker implantation is the definitive treatment for sick sinus syndrome when bradyarrhythmia has been documented to correlate with symptoms such as syncope or severe dizziness. 1

Initial Assessment and Medication Review

Before proceeding to pacemaker implantation, eliminate all medications that exacerbate bradycardia: 1, 2

• Beta-blockers are absolutely contraindicated in sick sinus syndrome unless a functioning pacemaker is already in place 1
• Non-dihydropyridine calcium channel blockers (verapamil, diltiazem) must be avoided 1
• Class IC antiarrhythmics (flecainide, propafenone) can unmask or worsen sinus node dysfunction 1
• Cardiac glycosides (digoxin), membrane-active antiarrhythmics (sotalol, amiodarone), and sympatholytic antihypertensives should be discontinued 2, 3

This medication elimination is critical because extrinsic factors may be mimicking or exacerbating intrinsic disease, and removing offending agents can prevent syncope recurrence. 2

Pacemaker Selection and Programming

Optimal Pacing Mode

Physiological pacing (atrial-based or dual-chamber) is superior to VVI pacing for sick sinus syndrome: 1, 2

• Atrial-based rate-responsive pacing is preferred to minimize exertion-related symptoms 1
• Dual-chamber rate-responsive pacemakers (DDDR) are most commonly used 1
• Newly developed atrial-based minimal ventricular pacing modes serve as alternatives to conventional DDDR pacing 1
• Consider biventricular pacing in patients with depressed left ventricular ejection fraction, heart failure, and prolonged QRS duration 1

Expected Outcomes

Pacemaker implantation provides: 1, 4

• Excellent symptomatic relief in the vast majority of patients (>95% experience improvement) 4
• Reduced risk of developing atrial fibrillation 1
• Lower incidence of syncope compared to no treatment 5
• Improved quality of life 1
• However, survival depends primarily on underlying cardiac disease, not the pacemaker itself 1, 4

Management of Tachyarrhythmias in Tachy-Brady Syndrome

For patients with the tachy-brady variant (approximately 50% of sick sinus syndrome cases): 2, 6

• Catheter ablation is first-line treatment for paroxysmal AV nodal reciprocating tachycardia, AV reciprocating tachycardia, or typical atrial flutter 1
• For atrial fibrillation or atypical left atrial flutter, treatment must be individualized based on symptoms and rate control 1
• Percutaneous cardiac ablative techniques may be considered for atrial tachyarrhythmia control 1

Monitoring Strategy

Pre-Pacemaker Monitoring

• Patients with symptomatic sinus bradycardia awaiting pacemaker implantation require continuous ECG monitoring until definitive pacing therapy is established 1
• Asymptomatic sinus bradycardia does not require in-hospital monitoring, as untreated sinus node dysfunction does not influence survival 1

Post-Pacemaker Considerations

Monitor for development of AV conduction disturbances, as the degenerative process affecting the sinus node often progresses to involve the AV node (occurs in approximately 36% of patients). 1, 4

Emergency Temporizing Measures

For symptomatic bradycardia requiring immediate management before pacemaker placement: 1

• Atropine may be used temporarily for emergency management 1
• Isoproterenol infusion can be used for refractory symptomatic bradycardia 1

Critical Pitfalls and Long-Term Considerations

Recurrent Syncope Despite Adequate Pacing

Approximately 20% of patients experience recurrent syncope during long-term follow-up despite adequate pacing due to associated vasodepressor reflex mechanisms. 1, 2 This occurs because:

• The degenerative process in sick sinus syndrome overlaps with autonomic dysfunction 2
• Vasovagal mechanisms persist independently of the bradycardia 2

For these patients, evaluate for: 2

• Orthostatic hypotension (measure blood pressure supine and after 3 minutes standing)
• Rapid ventricular response during atrial fibrillation episodes
• Consider tilt-table testing if prodromal symptoms suggest vasovagal mechanisms

Thromboembolic Risk

Systemic embolization occurs more frequently in patients with tachy-brady syndrome (27% in tachy-brady vs 6% in pure bradycardia), independent of pacemaker therapy. 4 Consider anticoagulation based on CHA₂DS₂-VASc score if atrial fibrillation develops.

Special Population: Sleep Apnea

Before implanting a pacemaker in patients with obesity, daytime tiredness, and symptomatic bradycardia, screen for sleep apnea-hypopnea syndrome, as treatment with nCPAP may resolve the bradyarrhythmia without need for permanent pacing. 7