From the Guidelines
Tachy brady syndrome, also known as sick sinus syndrome, is a cardiac condition that requires prompt treatment with permanent pacemaker implantation and antiarrhythmic medications to manage the bradycardia and tachycardia components, respectively, as evidenced by the European Heart Journal guidelines 1. The condition is characterized by alternating episodes of bradycardia (abnormally slow heart rate) and tachycardia (abnormally fast heart rate) due to dysfunction of the sinoatrial node, the heart's natural pacemaker. Patients typically experience symptoms such as:
- Dizziness
- Fatigue
- Shortness of breath
- Chest pain
- Palpitations
- Syncope (fainting) in severe cases The condition is more common in older adults and can be caused by age-related fibrosis of the cardiac conduction system, coronary artery disease, or other cardiac disorders. Diagnosis involves:
- ECG monitoring
- Holter monitoring
- Event recorders to capture the alternating rhythm disturbances Treatment usually requires:
- Permanent pacemaker implantation to manage the bradycardia component
- Antiarrhythmic medications like beta-blockers (metoprolol 25-100 mg twice daily), calcium channel blockers (diltiazem 120-360 mg daily), or amiodarone (200 mg daily after loading) to control tachyarrhythmias, as recommended by the American College of Cardiology/American Heart Association task force 1 In some cases, anticoagulation with warfarin (target INR 2-3) or direct oral anticoagulants may be necessary if atrial fibrillation is present to prevent stroke, as suggested by the European Heart Journal guidelines on management of syncope 1 The use of physiological pacing (atrial or dual-chamber) is superior to VVI pacing, as it lowers the risk of developing atrial fibrillation and improves quality of life 1.
From the Research
Definition and Characteristics of Tachy-Brady Syndrome
- Tachy-brady syndrome (TBS) is a complication of sick sinus syndrome (SSS) characterized by alternating tachycardia and bradycardia 2.
- SSS encompasses a group of disorders whereby the heart is unable to perform its pacemaker function, due to genetic and acquired causes 2.
- At least 50 percent of patients with SSS develop alternating bradycardia and tachycardia, also known as tachy-brady syndrome 3.
Electrophysiological Mechanisms
- 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.
- The transition from bradycardia to tachycardia is generally referred to as "tachy-brady syndrome" (TBS) 4.
Diagnosis and Treatment
- Diagnosis may be challenging, and is ultimately made by electrocardiographic identification of the arrhythmia in conjunction with the presence of symptoms 3.
- Treatment of SSS includes removing extrinsic factors, when possible, and pacemaker placement 3.
- Pacemakers do not reduce mortality, but they can decrease symptoms and improve quality of life 3.
- Many TBS patients are implanted a permanent pacemaker (PPM) to allow continuation of anti-arrhythmic drug (AAD) therapy to maintain sinus rhythm 5.
Management and Prognosis
- The mainstay treatment option for SSS is pacemaker implantation, an effective approach, but has disadvantages such as infection, limited battery life, dislodgement of leads and catheters to be permanently implanted in situ 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 2.
- Most TBS patients succeed to maintain sinus rhythm using an AAD with a significant pacing use, suggesting preventive PPM implantation might be advantageous in these cases 5.
- Only a minority of TBS patients progressed to permanent atrial fibrillation during the study follow-up period 5.