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Heart attack

Heart attack
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Complications of a heart attack

2-minute read

Potential complications arising from a heart attack can vary widely, from none to mild to life threatening.


An arrhythmia is an abnormal heartbeat, such as beating too quickly (‘tachycardia’), too slowly (‘bradycardia’) or irregularly.

Arrhythmias can develop after a heart attack as a result of damage to the muscles. Damaged muscles disrupt electrical signals used by the body to control the heart. Some arrhythmias are mild and can cause symptoms such as:

Mild arrhythmias can usually be controlled with medicine, such as beta blockers. More troublesome arrhythmias that cause repeated and prolonged symptoms may need to be treated with a pacemaker. A pacemaker is an electric device surgically implanted in the chest which is used to help regulate the heartbeat.

Other arrhythmias can be life threatening and can pose a risk of death during the first 24 hours after a heart attack:

  • ‘bradycardia’, a slow heart rate caused by complete heart block (where the electrical signal doesn’t travel from the top of the heart to the bottom of the heart)
  • ‘ventricular arrhythmia’, leading to sudden cardiac arrest (where the heart stops altogether)

However, survival rates have improved significantly since the invention of the defibrillator, an external device that delivers an electric shock to the heart and ‘resets’ it to the right rhythm. Learn more about defibrillators and how to perform CPR.

Heart failure

Heart failure is when your heart is unable to effectively pump blood around your body. It can develop after a heart attack if muscles in your heart are extensively damaged.

Symptoms of heart failure include:

  • shortness of breath
  • fatigue
  • swelling in your arms and legs due to a build-up of fluid

Heart failure can be treated with a combination of medicines and, in some cases, surgery. Learn more about heart failure.

Heart rupture

Heart rupture is a serious complication of a heart attack that occurs in about 10% of cases. The heart’s muscles, walls or valves split apart, usually one to five days after the heart attack. Open heart surgery is required to repair the damage. However, about half of all people die within 5 days of the rupture occurring.

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Last reviewed: July 2018

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