From the Guidelines
Tachy-Brady syndrome is a cardiac condition characterized by alternating episodes of abnormally fast and slow heart rhythms, typically affecting older adults and requiring implantation of a permanent pacemaker to regulate the heart rate. This disorder, also known as sick sinus syndrome, occurs when the sinus node develops scarring or fibrosis, often due to aging, heart disease, or other conditions that damage the heart's electrical system 1. The condition can cause symptoms like fatigue, dizziness, fainting, shortness of breath, and chest pain. Diagnosis usually involves ECG monitoring, Holter monitors, or event recorders to capture the rhythm changes.
Key Characteristics of Tachy-Brady Syndrome
- Alternating episodes of tachycardia and bradycardia
- Typically affects older adults
- Caused by scarring or fibrosis of the sinus node
- Symptoms include fatigue, dizziness, fainting, shortness of breath, and chest pain
- Diagnosis involves ECG monitoring, Holter monitors, or event recorders
Treatment and Management
Treatment typically requires implantation of a permanent pacemaker to regulate the heart rate, as medications alone are generally insufficient 1. Some patients may also need additional medications to control the tachycardia component, such as beta-blockers or calcium channel blockers. Without treatment, tachy-brady syndrome can lead to serious complications including stroke, heart failure, or sudden cardiac arrest, making proper diagnosis and management essential.
Important Considerations
- Evaluation of reversible causes for SND should be undertaken, and treatment may not be necessary in some cases, such as stopping a beta blocker in an asymptomatic patient with sinus bradycardia after ST-elevation MI 1
- Some patients with tachy-brady syndrome may have improvement of sinoatrial node function after treatment aimed at maintaining sinus rhythm 1
From the Research
Definition of Tachy-Brady Syndrome
- Tachy-brady syndrome (TBS) is a complication of sick sinus syndrome (SSS) characterized by alternating tachycardia and bradycardia 2, 3, 4.
- It is also known as tachycardia-bradycardia syndrome, and is marked by sudden alterations in heart rate, resulting in diverse symptoms such as palpitations, fatigue, lightheadedness, presyncope, and syncope 3.
Causes and Mechanisms
- TBS is etiologically variable, but the manifestations remain consistent throughout 3.
- Dysfunction of ion channels responsible for initiation or conduction of cardiac action potentials may underlie both bradycardia and tachycardia 2.
- Bradycardia can also increase the risk of tachycardia, and vice versa 2.
- Age-related interstitial fibrosis is considered to be the common pathophysiological mechanism between SSS and atrial fibrillation (AF), which can lead to TBS 5.
Diagnosis and Treatment
- Diagnosis of TBS may be challenging, and is ultimately made by electrocardiographic identification of the arrhythmia in conjunction with the presence of symptoms 4.
- Treatment of TBS includes removing extrinsic factors, when possible, and pacemaker placement 4, 6.
- Pacemakers do not reduce mortality, but they can decrease symptoms and improve quality of life 4.
- Alternatives to electronic pacemakers, such as gene-based bio-artificial sinoatrial node and cell-based bio-artificial pacemakers, are promising techniques whose long-term safety and efficacy need to be established 2.