From the Guidelines
Bradycardia is a condition characterized by an abnormally slow heart rate, typically defined as less than 60 beats per minute in adults, although some studies suggest a lower cutoff of 50 bpm may be more appropriate in certain populations 1.
Definition and Diagnosis
The definition of bradycardia can vary, but it is generally considered as a heart rate less than 60 bpm in adults, with the exception of well-trained athletes who may have a naturally lower heart rate without symptoms. According to the 2018 ACC/AHA/HRS guideline, a sinus rate <50 bpm and/or a sinus pause >3 seconds can be considered potential components of the definitions of sinus node dysfunction (SND) 1. However, the presence of sinus bradycardia or a pause >3 seconds alone should not be used for the diagnosis of SND; multiple factors should be recognized and taken into consideration for the individual patient.
Symptoms and Treatment
Bradycardia can cause insufficient blood flow to the body, leading to symptoms such as fatigue, dizziness, lightheadedness, fainting or near-fainting, shortness of breath, chest pain, confusion, or trouble concentrating. Treatment depends on the underlying cause and severity of symptoms. For severe or symptomatic bradycardia, a pacemaker may be recommended to maintain an appropriate heart rate 1. In emergency situations, medications like atropine (0.5-1mg IV) might be administered to temporarily increase heart rate.
Clinical Manifestations and Natural History
The clinical manifestations of bradycardia can vary widely, from insidious symptoms to episodes of frank syncope. The natural history of untreated bradycardia may be highly variable, with the majority of patients who have experienced syncope due to a sinus pause or marked sinus bradycardia likely to have recurrent syncope 1. The decision to implant a pacemaker for bradycardia is often accompanied by uncertainty that arises from incomplete linkage between sporadic symptoms and ECG evidence of coexisting bradycardia.
Key Considerations
- The heart normally beats 60-100 times per minute to efficiently circulate blood throughout the body; when the rate falls below this range, the body's organs may not receive enough oxygen and nutrients to function properly.
- The diagnosis of bradycardia requires careful individualized clinical assessment, and the presence of symptoms is a crucial factor in determining the need for treatment.
- Permanent cardiac pacing is the only effective treatment for symptomatic bradycardia, and the decision to implant a pacemaker should be based on a thorough evaluation of the patient's symptoms and ECG findings.
From the FDA Drug Label
Bradycardia, including sinus pause, heart block, and cardiac arrest have occurred with the use of metoprolol. Patients with first-degree atrioventricular block, sinus node dysfunction, or conduction disorders may be at increased risk. Monitor heart rate and rhythm in patients receiving metoprolol. If severe bradycardia develops, reduce or stop metoprolol Bradycardia (heart rate < 40 beats/min) 15.9%
Bradycardia is a condition where the heart beats too slowly, typically defined as a heart rate of less than 60 beats per minute.
- It can be caused by various factors, including the use of certain medications such as metoprolol.
- Symptoms of bradycardia may include fatigue, dizziness, and shortness of breath.
- In the context of metoprolol, bradycardia has been reported in approximately 3 of 100 patients and can be severe enough to require reduction or discontinuation of the medication 2.
- Monitoring of heart rate and rhythm is recommended in patients receiving metoprolol to promptly identify and manage any potential bradycardia 2.
From the Research
Definition of Bradycardia
- Bradycardia is defined as a heart rate of less than 50-60 bpm 3
- It can be observed as a normal phenomenon in young athletic individuals, and in patients as part of normal aging or disease 3
Causes of Bradycardia
- Pathology that produces bradycardia may occur within the sinus node, atrioventricular (AV) nodal tissue, and the specialized His-Purkinje conduction system 3
- Sinoatrial node dysfunction or AV block can be possible causes of bradycardia 4
Management of Bradycardia
- Management of bradycardia is based on the severity of symptoms, the underlying causes, presence of potentially reversible causes, presence of adverse signs, and risk of progression to asystole 4
- Pharmacologic therapy and/or pacing are used to manage unstable or symptomatic bradyarrhythmias 4
- Treatment should rarely be prescribed solely on the basis of a heart rate lower than an arbitrary cutoff or a pause above certain duration 3