What causes a slow heartbeat?

There are many causes of slow heartbeat, and they range from mild to serious.

Cardiovascular causes of a slow heartbeat

A slow heartbeat may be caused by cardiovascular disorders or diseases such as:

  • Cardiac arrhythmias
  • Cardiomyopathy (weakened or abnormal heart muscle and function)
  • Cardiovascular disease (due to atherosclerosis, hardening of the arteries, or other causes)
  • Sinus node disease (abnormality of the heart’s internal pacemaker)

Other causes of slow heartbeat

Other causes of slow heartbeat include:

  • Anorexia nervosa
  • Collagen vascular diseases
  • Electrolyte disturbances
  • Deep sleep
  • Excellent physical fitness
  • Fever
  • Heat exhaustion
  • Hypothermia
  • Hypothyroidism (underactive thyroid)
  • Malnutrition
  • Medication side effects
  • Old age
  • Regular exercise, which conditions the heart muscle and eventually slows the heart rate
  • Trauma
  • Tumors (intracranial, cervical, mediastinal)

Serious or life-threatening causes of slow heartbeat

In some cases, slow heartbeat may be a symptom of a serious or life-threatening condition that should be immediately evaluated in an emergency setting. These conditions include:

  • Cardiogenic shock (shock caused by heart damage and ineffective heart function)
  • Congestive heart failure (deterioration of the heart’s ability to pump blood)
  • Dissecting aortic aneurysm (life-threatening bulging and weakening of the aortic artery wall that can burst and cause severe hemorrhage)
  • Myocardial infarction (heart attack)
  • Myocarditis (infection of the middle layer of the heart wall)
  • Overdose, including cumulative overdose, of certain cardiac medications
  • Pericarditis (infection of the lining that surrounds the heart)
  • Trauma   

Questions for diagnosing the cause of a slow heartbeat

To diagnose your condition, your doctor or licensed health care practitioner will ask you several questions related to your slow heartbeat including:

  • How long have you been experiencing a slow heartbeat?
  • Do you feel a regular or irregular pattern to your heartbeat?
  • Do you feel that your heartbeat is stopping or skipping?
  • When does the slow heartbeat occur? Does it coincide with any specific activities?
  • Do you have any other symptoms?
  • What medications are you taking?

What are the potential complications of slow heartbeat?

Because a slow heartbeat can be due to serious diseases, failure to seek treatment can result in serious complications and permanent damage. Once the underlying cause is diagnosed, it is important for you to follow the treatment plan that you and your health care professional design specifically for you to reduce the risk of potential complications including:

  • Brain damage
  • Cardiac arrest
  • Difficulty breathing
  • Hypoxia (low levels of oxygen in the blood)
  • Respiratory failure and respiratory arrest
  • Unconsciousness and coma


  1. Bradycardia. MedlinePlus, a service of the National Library of Medicine National Institutes of Health. http://www.nlm.nih.gov/medlineplus/ency/imagepages/18033.htm.
  2. Bradycardia/Slow heart rate. http://www.heart.org/HEARTORG/Conditions/Arrhythmia/AboutArrhythmia/Bradycardia-Slow-Heart-Rate_UCM_...
  3. Kahan S, Miller R, Smith EG (Eds.). In A Page Signs & Symptoms, 2d ed. Philadelphia: Lippincott, Williams & Williams, 2009.
  4. Bope ET, Kellerman RD (Eds.) Conn’s Current Therapy. Philadelphia: Saunders, 2013.

What is a slow heartbeat?

A slow heartbeat is a heart rate that is below normal. The medical term for a slow heartbeat is bradycardia. The normal heart rate is 60 to 100 beats per minute. A slow heart rate is less than 60 beats per minute.

A slow heart rate may begin suddenly (acute) or develop over time (chronic). In some situations, a slow heart rate can occur as a result of chronic medical conditions. Read more about slow heartbeatintroduction


What other symptoms might occur with a slow heartbeat?

A slow heartbeat may accompany other symptoms, which vary depending on the underlying disease, disorder or condition. Symptoms that frequently affect the heart may also involve other body systems.

Common symptoms that may occur along with a slow heartbeat

A slow heartbeat may accompany symptoms that are related to other body systems including:

Medical Reviewer: William C. Lloyd III, MD, FACS Last Annual Review Date: Sep 30, 2013 Copyright: © Copyright 2014 Health Grades, Inc. All rights reserved. May not be reproduced or reprinted without permission from Health Grades, Inc. Use of this information is governed by the HealthGrades User Agreement.

This Article is Filed Under: Heart, Blood and Circulation