Irregular heartbeat and stroke: Understanding link between atrial fibrillation and blood clots

New Delhi: An irregular heartbeat can cause stroke or paralysis, and it is probably more common than you can imagine. One of the most common causes of an irregular heartbeat is a rhythm called atrial fibrillation, or AF.

To understand atrial fibrillation, we first need to understand a little bit about how the heart works. The heart has four chambers and is divided into two sides—the right and the left. Each side has a receiving chamber, called the atrium, and a pumping chamber, called the ventricle.

In atrial fibrillation, the atria, or the receiving chambers of the heart, stop contracting normally. Instead of contracting properly, they start quivering in a very irregular manner.

How atrial fibrillation leads to blood clots

When the atria are not contracting properly, blood can become relatively stagnant in certain areas. There is a small recess or pouch in the atrium called the atrial appendage, and this can become an area where blood stagnates, and a clot can form.

This is particularly important on the left side of the heart. A clot formed in the left atrium can get dislodged, enter the left ventricle — the main pumping chamber — and from there it can be pumped into the circulation.

If this clot travels to the brain and blocks one of the arteries supplying it, it can result in a stroke. The stroke can be small or large depending upon the size of the clot and the territory of the brain involved. In some patients, it can result in significant weakness or paralysis.

Causes and risk factors of atrial fibrillation

Atrial fibrillation can happen because of various heart diseases, but sometimes it can also develop simply with increasing age. In fact, atrial fibrillation is the most common sustained abnormal heart rhythm, and its incidence increases significantly as we grow older.

There are certain conditions which make it more likely. High blood pressure, valvular heart disease, coronary artery disease, heart failure and any condition which leads to enlargement of the atria can predispose a person to atrial fibrillation.

It is actually quite easy to understand why.

The normal heartbeat depends upon electrical impulses travelling through the heart in an organised manner. When the atria enlarge, the heart muscle gets stretched, and the normal electrical pathways can get disturbed. The electrical impulses then start travelling through multiple abnormal pathways, and instead of an organised contraction, the atria start beating in a completely irregular manner.

The importance of atrial fibrillation is not only because of the risk of stroke. If it continues for a long time and remains untreated, particularly when the heart rate remains high, it can also eventually lead to weakening of the heart and reduction in heart function.

Symptoms, diagnosis and treatment of atrial fibrillation

Whenever you feel palpitations, a racing heartbeat or an irregular heartbeat—sometimes even while you are simply sitting at rest — do not ignore it.

These episodes can come and go. You may have an episode for some time, and then the heartbeat becomes normal on its own. Because it gets better, people tend to ignore it. But if you have repeated episodes like this, even if they settle on their own, you should get yourself checked.

Sometimes a simple ECG will pick it up. If the episodes are intermittent, longer monitoring of the heart rhythm may be required.

There are now many ways of treating atrial fibrillation. Depending upon the age of the patient, the underlying cause and the type of atrial fibrillation, treatment can range from simple medications to catheter-based procedures such as ablation.

And importantly, in patients who are at significant risk of stroke, blood-thinning medicines may be required to prevent clot formation.

Palpitations or an irregular heartbeat are not something that should be ignored.

They may turn out to be harmless, but they may also be the first sign of atrial fibrillation. And something which starts simply as an irregular heartbeat, if left undetected or untreated in a person at risk, can sometimes result in a major and even life-threatening stroke.

(By Dr Vaibhav Mishra, Principal Director, CTVS, Cardiac Sciences, Max Hospital, New Delhi)

Disclaimer: This article is based on the research and inputs shared by the doctor mentioned above and is intended for informational purposes only. The findings should not be considered medical advice or used for self-diagnosis or treatment. Consult a qualified healthcare professional for personalised guidance.