What Are the Dangers of Rapid Heart Rate?

A rapid heartbeat is called tachycardia. A healthy heart beats 60 to 100 times per minute in a resting adult. In tachycardia, the heart beats over 100 times per minute. Tachycardia occurs when a heart malfunction quickens the electrical signals that make the heart beat. Although some people with tachycardia do not have complications or symptoms, tachycardia can lead to serious health problems and even death.

Blood Clots

A rapid heartbeat may cause blood clots, which form when the blood pools in the heart. This pooled blood hardens to form a blood clot. A thrombus is a blood clot that forms and remains in the heart. An embolism occurs when a blood clot leaves the heart and moves to another part of the body (such as a lung embolism). A stroke may result if the blood clot travels to the brain.


An individual with a rapid heartbeat may faint, or lose consciousness temporarily. A lack of blood flow to the brain causes fainting. Rapid heartbeats can make the heart less productive so less blood flows to the body, including the brain.

Heart Attack

A rapid heartbeat may cause a heart attack, or damage to the heart from a lack of blood supply. The heart works more and needs more oxygen when the heart beats quickly. However, less blood is pumped to the body, including the heart, because a fast heartbeat causes the heart to work less effectively. This decreased flow of blood and oxygen to the heart causes part of the heart to die, thus causing a heart attack.

Heart Failure

Heart failure is when the heart is unable to pump enough blood to the body. A rapid heartbeat causes the heart to work inefficiently, thus blood flows more slowly through the body. This decreased flow of blood means that the body does not get enough blood, oxygen and nutrients. As a result, someone with heart failure can experience fatigue and shortness of breath.

Sudden Cardiac Death (Cardiac Arrest)

Rapid beating of heart ventricles (ventricular tachycardia) may cause sudden cardiac death (cardiac arrest), or natural death resulting from the heart not functioning. The ventricles pump the blood to the body. A few rapid beats of the ventricles are usually not problematic, but death may result when the rapid beating lasts longer than a few seconds. The rapid beating causes the heart to stop beating entirely. Although death begins to occur within 4 to 6 minutes after cardiac arrest, a person can be resuscitated if an electric shock to the heart (defibrillation) is administered within a few minutes after the cardiac arrest begins. Survival is unlikely after 10 minutes of resuscitation.

About this Author

Dr. Mary Lehrman is a licensed psychologist with a Ph.D. in health psychology. She has been published in academic journals and has more than 10 years of experience helping people improve their health.