Having suffered a heart attack (or a myocardial infarction as it is also called) and getting treated for it, is not the end of the story. There may be side effects or complications of the heart attack, some of which can be life-threatening.

About 12 percent of people who have a heart attack will succumb to it. There are causes and risk factors associated with a heart attack. While coronary artery disease (CAD) is the main and most dangerous cause of heart attack, hypertension and smoking are the most common risk factors that can lead to a heart attack and cause complications.

You may suffer a mild heart attack with no complications or you may suffer a massive heart attack, which can cause a number of complications and needs extensive treatment. Some occur short-term while some are long-term

These possible complications that ensue after a heart attack will depend on two things:

  1. The portion of the heart where the heart attack or the myocardial infarct has occurred
  2. The extent of damage to the heart muscle

According to SCAI, for a better prognosis, you have approximately 90 minutes between the onset of heart attack and its symptoms and getting medical treatment to prevent damage to heart tissue and minimize the risk of complications. It is, therefore, important that a person having a heart attack get first aid immediately.

Heart attack complications

Some heart attack complications arise early immediately after the heart attack during the acute phase while some complications come a little late.

We shall discuss below and see what those potential problems of heart attack are. You should know the risk of these complications is very high if the heart attack is left untreated. The longer a heart attack is left untreated, the more the damage to the heart, which leads to a worse outcome.

We have also explained how these complications present with symptoms and the treatment of these complications.

1. Arrhythmias

An arrhythmia is an abnormal beating of the heart. It can include a rapid heartbeat (tachycardia), a slow heartbeat (bradycardia), or an irregular beating of the heart (fibrillation).

The normal beating of the heart follows a particular pattern.

  • The upper chambers, called the atria, contract to push the blood into the lower chambers, called the ventricles, which relax to admit the blood.
  • The lower chambers then contract to pump out the blood to the lungs and various parts of the body through the arteries.
  • At the same time, the upper chambers have relaxed to admit the blood returning from the lungs and the rest of the body.

What makes this happens? 

This is brought about by an electrical impulse that follows a particular pathway within the walls of the heart and makes the heart contract in a normal fashion.

In a patient with a heart attack, since there is damage to the part of the heart wall, the path of the electrical impulse is disturbed and the normal beating of the heart may be altered. The heart beats in an abnormal way and this abnormal beating of the heart is called arrhythmia.

Either the upper chambers of the heart may beat abnormally in which case it is called atrial fibrillation. The abnormal beating of the lower heart chambers is called ventricular fibrillation. 

Atrial fibrillation is mild and is treated with medicines while ventricular fibrillation is life-threatening and is a major cause of post-heart attack deaths.

Arrhythmias are a major cause of death after a heart attack during the first 24 hours.

Tachycardia can cause symptoms such as

  • Palpitation
  • Chest pain
  • Giddiness
  • Breathlessness
  • Fatigue

Arrhythmias can be treated by

  • Medicines
  • Electric shocks to the chest to stimulate the impulse
  • Inserting a pacemaker in the heart

Nowadays, survival rates have improved significantly due to the portable defibrillator. This is an instrument, which delivers a shock to the heart to reset its normal rhythm. This has allowed many people to live a long quality life after a heart attack.

2. Heart failure

Heart failure or cardiac failure as it is also called is a long-term complication of a heart attack.  It occurs in patients whose left ventricular heart wall is damaged by more than 30%. The heart is unable to pump blood effectively and the patient suffers from congestive cardiac failure (CCF).

CCF can present with the following signs and symptoms:

  • Fatigue
  • Shortness of breath
  • Swelling of the arms and the legs

There are a number of medicines to treat heart failure and the doctor chooses the option most suitable to the particular case. Surgery may also be required in some cases.

3. Rupture of the heart wall

Because of the weakened heart wall, a tear or rupture may occur in the wall of the heart due to which, the blood may spill into the sac covering the heart (pericardium).

A rupture may also occur in the septal wall in which case the blood between the right and left chambers of the heart may intermingle. However, these complications are rare.

Symptoms include

  • Pale and cold skin
  • Mental confusion
  • Fast heartbeat
  • Increased rate of breathing
  • Decreased or no urinary output

The prognosis is not good and about half of the patients with this complication die within five days of the rupture.

4. Pericarditis

This is an inflammation of the pericardial sac, which covers the heart. This may occur shortly after an attack and the pericardial sac gets filled with fluid. This can be treated with medicines.

Symptoms include chest pain of the stabbing type, which increases with a deep breath, coughing, swallowing, or also on lying flat. The pain is relieved by sitting and bending forward.

5. Clot formation

The formation of a clot may occur especially when the wall of the left ventricle has suffered an infarct and is damaged. The blood flow is slower than normal and this may contribute to clot formation.

Secondly, prolonged bed rest and inactivity (such as prolonged hospitalization or a long flight) may give rise to clot formation in the deep veins of the legs. This is called deep vein thrombosis.

These clots then migrate to the lungs through the heart and may result in pulmonary embolism, which is life-threatening.

6. Heart valve damage

There are one-way valves between the upper chambers and lower chambers of the heart that direct the blood flow within the heart.

After a heart attack, these heart valves can get damaged and it can lead to their incontinence. This causes the valves to dysfunction and leak blood in the opposite direction.

7. Repeat heart attack

About 20% of heart attack patients may suffer another attack within six weeks of the previous one. The attack may occur in the same area or another one. Aggressive management is urgently required.

Prompt treatment is the key to preventing these complications and improving the prognosis. Due to advances in treatment methods, the chances of dying of a heart attack are now at a historic low of 12 percent.

According to the National Health Service (NHS), many people with untreated heart attacks develop complications of arrhythmias, cardiac shock, and cardiac failure. They die suddenly from such complications — some before they reach the hospital and others within the first month of having a heart attack.