From the Guidelines
Sick sinus syndrome is a disorder where the heart's natural pacemaker (sinus node) doesn't function properly, causing abnormally slow heart rates, pauses in the heart rhythm, or alternating fast and slow rhythms, and treatment typically involves implanting a permanent pacemaker to regulate the heart rate, especially for symptomatic patients experiencing dizziness, fatigue, shortness of breath, or fainting, as recommended by the most recent guidelines 1.
Diagnosis and Treatment
The diagnosis of sick sinus syndrome is based on the presence of symptoms such as syncope, dizziness, fatigue, and shortness of breath, as well as electrocardiographic evidence of sinus node dysfunction, including persistent sinus bradycardia, sinus arrest, or chronotropic incompetence.
- The treatment of sick sinus syndrome involves implanting a permanent pacemaker to regulate the heart rate, with atrial-based pacing (AAI or DDD) being preferred over VVI pacing due to its ability to reduce the risk of stroke and atrial fibrillation 1.
- Medications that slow heart rate, such as beta-blockers, calcium channel blockers, and certain antiarrhythmics, should be avoided or used cautiously, as they can exacerbate underlying susceptibility to bradycardia and create pauses of sufficient duration to result in syncope 1.
- For patients with both slow rhythms and episodes of atrial fibrillation, anticoagulation therapy may be needed to prevent blood clots and stroke, as the incidence of systemic embolism is higher in untreated patients with sick sinus syndrome 1.
Ongoing Monitoring and Management
- Patients with sick sinus syndrome should be monitored regularly for new or worsening symptoms, and adjustments to pacemaker settings or medications may be necessary to optimize treatment.
- The condition often progresses over time, and ongoing monitoring is essential to prevent complications such as atrial fibrillation, stroke, and sudden cardiac death.
- The natural history of untreated sick sinus syndrome may be highly variable, with some patients experiencing recurrent syncope and others remaining asymptomatic, highlighting the importance of individualized treatment and monitoring 1.
From the Research
Diagnosis of Sick Sinus Syndrome (SSS)
- SSS is diagnosed by electrocardiographic identification of the arrhythmia in conjunction with the presence of symptoms 2
- If electrocardiography does not yield a diagnosis, inpatient telemetry monitoring, outpatient Holter monitoring, event monitoring, or loop monitoring may be used 2
- Electrophysiologic studies also may be used but are not routinely needed 2
Treatment of Sick Sinus Syndrome (SSS)
- The mainstay treatment option for SSS is pacemaker implantation, which is an effective approach 3, 4, 2
- Pacemakers do not reduce mortality, but they can decrease symptoms and improve quality of life 2
- Alternatives to electronic pacemakers are gene-based bio-artificial sinoatrial node and cell-based bio-artificial pacemakers, which are promising techniques whose long-term safety and efficacy need to be established 4
- Cilostazol may be effective for symptomatic SSS to avoid PM implantation by increasing heart rate 5
- Theophylline may be beneficial for the treatment of patients with SSS, decreasing the frequency and duration of sinus pauses and alleviating subjective symptoms 6
Symptoms and Prognosis
- Symptoms of SSS are often subtle early on and become more obvious as the disease progresses, commonly related to end-organ hypoperfusion 2
- Cerebral hypoperfusion is most common, with syncope or near-fainting occurring in about one-half of patients 2
- The prognosis is mainly determined by the presence or absence of coronary heart disease and/or heart failure 3