What are the symptoms of bradycardia (abnormally slow heart rate)?

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From the Guidelines

Bradycardia symptoms include fatigue, dizziness, lightheadedness, fainting or near-fainting spells, shortness of breath, chest pain, confusion, difficulty exercising, and weakness, as defined by the 2018 ACC/AHA/HRS guideline on the evaluation and management of patients with bradycardia and cardiac conduction delay 1.

Symptoms of Bradycardia

The symptoms of bradycardia can vary widely from insidious symptoms to episodes of frank syncope, and can be broadly classified into two general categories: sinoatrial node dysfunction (SND) and atrioventricular block 1.

  • Fatigue
  • Dizziness
  • Lightheadedness
  • Fainting or near-fainting spells
  • Shortness of breath
  • Chest pain
  • Confusion
  • Difficulty exercising
  • Weakness These symptoms typically occur when the heart rate drops below 50 beats per minute, resulting in inadequate oxygen delivery to tissues and organs 1.

Clinical Manifestations

The clinical manifestations of bradycardia can be explained by the disparate electrophysiologic manifestations, ventricular rates, transience of these abnormalities, overall medical conditions, and medications 1.

  • The electrocardiographic findings in patients with SND are varied and the diagnosis may be considered in patients with sinus bradycardia or atrial depolarization from a subsidiary pacemaker other than the sinus node.
  • The clinical manifestations of atrioventricular block will also depend on whether the atrioventricular block is fixed or intermittent and the ventricular rate or duration of ventricular asystole associated with atrioventricular block. Regardless of whether the bradycardia is caused by SND or atrioventricular block, the term “symptomatic bradycardia” is used throughout the guideline and has been defined as a “documented bradyarrhythmia that is directly responsible for development of the clinical manifestations of syncope or presyncope, transient dizziness or lightheadedness, heart failure symptoms, or confusional states resulting from cerebral hypoperfusion attributable to slow heart rate” 1.

Importance of Medical Attention

If you experience these symptoms, especially fainting or severe shortness of breath, seek medical attention promptly as treatment may be needed, ranging from medication adjustments to pacemaker implantation in severe cases 1.

From the Research

Symptoms of Bradycardia

The symptoms of bradycardia, which is a heart rate lower than 60 beats/min, can include:

  • Syncope
  • Dizziness
  • Chest pain
  • Dyspnea
  • Fatigue 2 These symptoms can occur due to various types of bradycardia, such as sinus, atrial, or junctional bradycardia, or problems with the conduction system, like an atrioventricular block 2.

Clinical Presentation

Bradycardia can be asymptomatic, especially in trained athletes or during sleep 2. However, symptomatic patients may present with decreased end-organ perfusion, requiring prompt recognition and treatment 3. In some cases, bradycardia can lead to more severe complications, such as ventricular standstill, loss of consciousness, and decorticate posturing 4.

Treatment-Related Symptoms

In some instances, treatment of bradycardia with atropine can paradoxically worsen the condition, particularly in patients with atrioventricular blocks at the level of the His-Purkinje fibers 4. Additionally, transcutaneous cardiac pacing (TCP) can be a painful intervention, although it is generally well-tolerated by conscious patients 5.

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Research

The efficacy of transcutaneous cardiac pacing in ED.

The American journal of emergency medicine, 2016

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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