Complications of coronary artery disease

Over time, CAD can cause part of the heart to lose strength (heart failure, also known as cardiac insufficiency). Depending on which part of the heart is affected, heart failure can cause different problems: If the right side of the heart is weak, blood builds up in the veins that carry blood from the tissue and organs to the heart. This can cause edema (swelling) in the legs and, if the heart failure is advanced, in the abdomen (belly) or liver too.

If the left side of the heart is weak, blood builds up in the vessels that carry blood away from the lungs. This may cause shortness of breath, especially during more strenuous activities. Sometimes, heart failure affects both the left and right sides of the heart.

The severity of heart failure can vary quite a lot. There may be no symptoms or only mild symptoms, or it could greatly reduce your physical fitness. The possible symptoms include exhaustion, shortness of breath, chest pain and heart palpitations. In severe heart failure, it is even difficult to do normal everyday activities like walking longer distances or climbing a short flight of stairs.

Our heartbeat is regulated by special muscle cells in certain areas of the heart. These cells send electrical signals that make the heart beat.

If the heart no longer gets enough oxygen because of CAD, the special muscle cells may become damaged. As a result, the heart rate may be irregular, or the heart may beat faster or slower. This can lead to a pounding or racing heart, tiredness or dizziness. An irregular heartbeat can be diagnosed with the help of an electrocardiogram (ECG). The most common type of irregular heartbeat is known as atrial fibrillation.

Heart rhythm problems can reduce the heart's pumping strength, which can cause heart failure or make existing heart failure worse. But arrhythmia might also be the result of CAD-related heart failure, or of a heart attack.

Some types of irregular heartbeat, like atrial fibrillation, can cause blood clots to form in the heart. If blood clots are carried around the body in the bloodstream, they can cause problems if they block a blood vessel somewhere (for instance, a stroke in the brain). If another type of arrhythmia called ventricular tachycardia occurs, it can turn into life-threatening ventricular fibrillation.

CAD increases the risk of a heart attack even if it hasn’t caused any other symptoms before. People who have already had a heart attack are more likely to have (further) heart attacks.

Heart attacks happen if a coronary artery becomes completely blocked or almost completely blocked. The blockage stops part of the heart muscle from getting enough oxygen. If this goes on for too long, that part of the heart muscle dies and the situation becomes life-threatening. It is then important to get medical help immediately.

But the odds of surviving a heart attack are good: Most people in Germany and many other countries survive heart attacks nowadays.

There are two main types of heart attack. Doctors call them

• ST segment elevation myocardial infarctions (STEMI) and
• non-ST segment elevation myocardial infarctions (NSTEMI).

A heartbeat is seen as a wave-like form on an electrocardiogram (ECG). In STEMI, a certain part of the wave is abnormal. In NSTEMI, this part of the wave is normal.

Most heart attacks are treated using a thin flexible tube called a cardiac (heart) catheter. This procedure is known as angioplasty. The blood clot that blocked the coronary artery can sometimes be broken up and removed by fast-acting medication given through a drip (thrombolysis).

Medication is also needed afterwards. This is firstly meant to prevent another heart attack and to lower the risk of other complications. Having a heart attack is itself associated with further complications: It can leave behind a scar in the heart tissue that causes arrhythmias that can lead to sudden cardiac death months or even years later, especially if the heart was permanently weakened by the heart attack.

That is why a defibrillator is recommended in addition to the medication. It can effectively prevent life-threatening complications. The tissue around the scar can also be removed (catheter ablation) to lower the risk of arrhythmias being triggered there.