What is the recommended treatment for a patient with sick sinus syndrome, including management of underlying conditions such as high blood pressure and coronary artery disease?

Management of Sick Sinus Syndrome

Permanent pacemaker implantation is the definitive treatment for sick sinus syndrome when bradyarrhythmia has been documented to correlate with symptoms, and dual-chamber rate-responsive (DDDR) pacing is superior to single-lead atrial pacing. 1, 2, 3

Initial Assessment and Reversible Causes

Before proceeding with permanent pacing, eliminate medications that exacerbate bradycardia 2, 4:

• Discontinue beta-blockers (contraindicated in sick sinus syndrome) 2
• Avoid non-dihydropyridine calcium channel blockers (verapamil, diltiazem) 2
• Stop or reduce cardiac glycosides, membrane-active antiarrhythmics, and Class IC agents if possible 4, 5
• Correct electrolyte abnormalities before attributing symptoms to intrinsic disease 1

Pacemaker Selection and Programming

Dual-chamber rate-responsive (DDDR) pacing is the preferred mode for the following reasons 2, 3:

• Reduces atrial fibrillation risk compared to ventricular (VVI) pacing 1, 2
• Lowers stroke risk (HR 0.81) compared to VVI pacing 1
• Superior to single-lead atrial (AAIR) pacing, which carries a 27% higher risk of paroxysmal atrial fibrillation and doubles the reoperation rate 3
• Improves quality of life by maintaining AV synchrony and rate responsiveness during exercise 1, 2

Newly developed atrial-based minimal ventricular pacing modes are recommended as alternatives to conventional DDDR pacing 2.

Management of Coexisting Conditions

High Blood Pressure

• Use dihydropyridine calcium channel blockers (amlodipine, nifedipine) rather than non-dihydropyridines 2
• ACE inhibitors or ARBs are safe alternatives that do not affect sinus node function
• Avoid beta-blockers unless the pacemaker provides adequate backup pacing 4

Coronary Artery Disease

• Optimize medical therapy with aspirin, statins, and ACE inhibitors 6, 7
• Prognosis is primarily determined by the presence of coronary disease and heart failure, not the arrhythmia itself 6, 7, 8
• Consider revascularization if indicated by ischemic burden
• Pacemaker therapy reduces heart failure incidence in SSS patients 9

Tachy-Brady Syndrome (Atrial Fibrillation Component)

When paroxysmal atrial fibrillation coexists with bradycardia 2, 4, 5:

• Catheter ablation is first-line treatment for paroxysmal AV nodal reciprocating tachycardia, AV reciprocating tachycardia, or typical atrial flutter 2
• For atrial fibrillation, consider catheter ablation if rate control is inadequate despite pacemaker 4
• Rate control agents can be used cautiously after pacemaker implantation, but avoid beta-blockers and non-dihydropyridine calcium blockers unless adequate backup pacing is confirmed 4

Monitoring Strategy

Pre-Pacemaker Monitoring

• Continuous ECG monitoring is required for symptomatic patients awaiting pacemaker implantation 2
• Asymptomatic sinus bradycardia does not require in-hospital monitoring, as untreated sinus node dysfunction does not influence survival 2

Post-Pacemaker Follow-Up

• Expect syncope recurrence in approximately 20% of patients despite adequate pacing due to vasodepressor reflex mechanisms 2, 4
• Evaluate for orthostatic hypotension by measuring blood pressure supine and after 3 minutes standing 4
• Consider tilt-table testing if vasovagal symptoms persist 4

Critical Pitfalls to Avoid

• Do not use Class IC antiarrhythmics (flecainide, propafenone) out-of-hospital in symptomatic SSS due to risk of worsening sinus node dysfunction and AV block 2
• Do not combine ivabradine with non-dihydropyridine calcium channel blockers 2
• Do not delay pacemaker implantation in patients with documented symptomatic bradycardia, as this is the only therapy proven to relieve symptoms 1, 2
• Do not use VVI pacing as it increases stroke and atrial fibrillation risk compared to physiologic pacing 1

Expected Outcomes

• Symptomatic improvement occurs in >95% of patients after pacemaker implantation 6
• Survival is not improved by pacing alone; prognosis depends on underlying cardiac disease (coronary disease, heart failure) 6, 7, 8
• Systemic embolization risk is higher in tachy-brady syndrome (27%) compared to bradycardia alone (6%) 6
• Chronic atrial fibrillation develops in some patients during follow-up, which may terminate the clinical syndrome 7