From the Guidelines
No, Sick Sinus Syndrome (SSS) is not considered an ischemic heart disease. SSS is a disorder of the heart's natural pacemaker (sinoatrial node) that causes abnormal heart rhythms, while ischemic heart disease results from reduced blood flow to the heart muscle due to coronary artery blockages.
Key Characteristics of SSS
- SSS is primarily an electrical conduction problem characterized by inappropriate sinus bradycardia, sinus pauses, sinus arrest, or alternating bradycardia and tachycardia (tachy-brady syndrome) 1.
- The condition is often age-related and can be caused by fibrosis and degeneration of the sinoatrial node, medications, or other cardiac conditions.
- Some key manifestations of sinus node dysfunction include sinus arrest, ectopic atrial or AV junctional escape rhythm, and lack of an adequate chronotropic response to exercise 1.
Treatment and Management
- Treatment typically involves addressing underlying causes, discontinuing contributing medications, and often pacemaker implantation for symptom management.
- While both conditions can coexist in elderly patients, they have different pathophysiological mechanisms - SSS involves dysfunction of the cardiac conduction system, whereas ischemic heart disease involves inadequate blood supply to cardiac muscle tissue.
Clinical Considerations
- It is essential to correlate symptoms with the specific arrhythmias, although this may be difficult due to the intermittent nature of the episodes 1.
- Sinus bradycardia is accepted as a physiologic finding in trained athletes, who not uncommonly have heart rates of 40-50 beats/min while at rest and awake and may have sleeping rates as slow as 30-43 beats/min 1.
From the Research
Definition and Characteristics of Sick Sinus Syndrome (SSS)
- SSS is a term used to describe dysfunction of the sinoatrial (SA) node that can lead to various cardiac arrhythmias, predominately manifesting in the elderly 2.
- Commonly implicated arrhythmias vary from inappropriate bradycardia, tachycardia, sinus pauses, and rarely sinus arrest 2, 3.
- SSS results from intrinsic causes, such as degenerative fibrosis, ion channel dysfunction, and remodeling of the sinoatrial node, or may be exacerbated or mimicked by extrinsic factors, including pharmacologic, metabolic, or autonomic factors 3.
Relationship between SSS and Ischemic Heart Disease
- There is no direct evidence to suggest that SSS is considered ischemic heart disease 2, 3, 4, 5, 6.
- However, SSS can coexist with other cardiovascular conditions, including coronary heart disease, heart failure, and atrial fibrillation, which may be related to ischemic heart disease 5.
- The presence of SSS has been associated with an increased risk of cardiovascular disease and mortality, including coronary heart disease, heart failure, and stroke, but the mechanisms underlying these associations are not fully understood 5.
Diagnosis and Treatment of SSS
- Diagnosis of SSS is made by electrocardiographic identification of the arrhythmia in conjunction with the presence of symptoms, and may involve inpatient telemetry monitoring, outpatient Holter monitoring, event monitoring, or loop monitoring 3.
- Treatment of SSS includes removing extrinsic factors, when possible, and pacemaker placement, which can decrease symptoms and improve quality of life, but does not reduce mortality 3, 4.