What are the symptoms of bradycardia?

Symptoms of Bradycardia

The primary symptoms of bradycardia include fatigue, dizziness, lightheadedness, pre-syncope, syncope, and confusional states resulting from cerebral hypoperfusion due to slow heart rate. 1

Common Symptoms

Bradycardia symptoms vary widely in presentation and severity depending on the heart rate, duration of the bradycardia, and underlying cause. The most common symptoms include:

• Cerebral hypoperfusion symptoms:

  • Dizziness/lightheadedness
  • Pre-syncope (near-fainting)
  • Syncope (fainting)
  • Confusion or altered mental status

• Cardiovascular symptoms:

  • Fatigue
  • Exercise intolerance
  • Heart failure symptoms
  • Chest pain/angina pectoris 2

• Other symptoms:

  • Shortness of breath (dyspnea)
  • Irritability
  • Lassitude
  • Inability to concentrate
  • Apathy
  • Forgetfulness 1

Symptom Severity and Correlation

The severity of symptoms generally correlates with:

1. The absolute heart rate (lower rates typically cause more symptoms)
2. The duration of bradycardia episodes
3. The presence of underlying cardiovascular disease

It's important to note that many patients with bradycardia may be completely asymptomatic, particularly:

• Young, healthy individuals
• Athletes with physiologic bradycardia
• During sleep 1
• When bradycardia develops gradually, allowing for compensatory mechanisms

Types of Bradycardia and Associated Symptoms

Different types of bradycardia may present with varying symptom patterns:

Sinus Node Dysfunction (SND)

• May present with intermittent symptoms correlating with episodes of bradycardia
• Can manifest as sinus bradycardia, sinus pauses, or chronotropic incompetence (inability to increase heart rate with exertion) 1

Atrioventricular (AV) Block

• Symptoms depend on whether the block is fixed or intermittent
• Higher-degree blocks (Mobitz type II second-degree and third-degree/complete heart block) typically cause more severe symptoms 1
• Sudden onset complete heart block may cause Morgagni-Adams-Stokes attacks (sudden syncope) 3

Special Considerations

1. Vagally-mediated bradycardia:

   • May occur at night during sleep when parasympathetic tone increases
   • Often asymptomatic when occurring during sleep 1

2. Drug-induced bradycardia:

   • May cause gradual onset of symptoms
   • Common medications include beta-blockers, calcium channel blockers, digoxin, and certain antiarrhythmics 1

3. Bradycardia in cancer patients:

   • May be related to chemotherapy agents (cisplatin, paclitaxel, thalidomide, etc.)
   • Can be asymptomatic in many cases 1

When to Seek Medical Attention

Patients should seek immediate medical attention for:

• Syncope or near-syncope episodes
• Persistent dizziness with slow heart rate
• Chest pain with bradycardia
• Shortness of breath with bradycardia

Clinical Pitfalls

1. Symptom attribution challenges:

   • Direct attribution of symptoms solely to bradycardia can be difficult
   • In vasovagal syncope, bradycardia often occurs with vasodepressor effects 1
   • Nonspecific symptoms like fatigue may have multiple causes

2. Asymptomatic bradycardia:

   • Requires no treatment in most cases 4
   • Overtreatment carries risks of unnecessary pacemaker implantation

3. Overlooking reversible causes:

   • Always evaluate for medication effects, thyroid dysfunction, electrolyte abnormalities, and sleep apnea before considering permanent interventions 4

Remember that correlation between symptoms and documented bradyarrhythmia is essential when determining the need for treatment, as there is no defined heart rate threshold below which treatment is automatically indicated 1.