Heart attack : Complications

Potential complications from a heart attack can vary widely, from mild to life threatening.

Some people experience a "minor" heart attack (although it can still be very serious) with no associated complications. This is also known as an uncomplicated heart attack.

Other people experience a major heart attack, which has a wide range of potential complications and may require extensive treatment.

Some common complications of a heart attack are discussed in more detail below.


An arrhythmia is an abnormal heartbeat – this includes:

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, such as tachycardia, are mild and cause symptoms such as:

Other arrhythmias can be life threatening, such as:

  • complete heart block, where electrical signals are unable to travel from one side of your heart to the other, so your heart cannot pump blood properly
  • ventricular arrhythmia, where the heart begins beating faster before going into a spasm and stops pumping altogether; this is known as sudden cardiac arrest – see symptoms of a heart attack for more information

These life-threatening arrhythmias can be a major cause of death during the 24-48 hours after a heart attack.

However, survival rates have improved significantly since the invention of the portable defibrillator – an external device that delivers an electric shock to the heart and "resets" it to the right rhythm.

Mild arrhythmias can usually be controlled with medication such as beta-blockers.

More troublesome bradycardias that cause repeated and prolonged symptoms may need to be treated with a pacemaker. This is an electric device surgically implanted in the chest, which is used to help regulate the heartbeat.

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Heart failure

Heart failure happens when your heart is unable to effectively pump blood around your body. It can develop after a heart attack if your heart muscle is extensively damaged. This usually occurs in the left side of the heart (the left ventricle).

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 medications and, in some cases, surgery.

Read more about treating heart failure.

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Cardiogenic shock

Cardiogenic shock is similar to heart failure, but more serious. It develops when the heart muscle has been damaged so extensively it can no longer pump enough blood to maintain many of the body's functions.

Symptoms include:

  • mental confusion
  • cold hands and feet
  • decreased or no urine output
  • rapid heartbeat and breathing
  • pale skin
  • difficulty breathing

A type of medication called vasopressors (or inotropes) may be used. Vasopressors help constrict (squeeze) the blood vessels, which increases the blood pressure and improves blood circulation.

Once the initial symptoms of cardiogenic shock have been stabilised, surgery may be required to improve the functioning of the heart. This may still include PCI, alongside the insertion of a small pump, known as an intra-aortic balloon pump. This can help improve the flow of blood away from the heart.

Another option is a coronary artery bypass graft (where a blood vessel from another part of your body is used to bypass any blockage).

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Heart rupture

A heart rupture is an extremely serious but relatively uncommon complication of heart attacks where the heart's muscles, walls or valves rupture (split apart).

It can occur if the heart is significantly damaged during a heart attack and usually happens 1 to 5 days afterwards.

Symptoms are the same as those of cardiogenic shock. Open heart surgery is usually required to repair the damage.

The outlook for people who have a heart rupture isn't good, and it's estimated that half of all people die within five days of the rupture occurring.

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