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stress ECG

Atrial Fibrillation

What is Atrial Fibrillation (AF)?

 When your heart beats irregular, and out of rhythm, you have Atrial Fibrillation or AF. Imagine your clock or watch instead of moving forward regularly, second by second, moving forward erratically; one tick, for one second, the next tick, three seconds and the next 2 seconds, etc., without any order. In AF, one heartbeat might take 1 second, the next 0.5 seconds and the next 2 seconds. 

The average acceptable heart rate is usually between 60-100 beats per minute, but in AF, your heart rate can increase to more than 150 beats per minute, even at rest. So your heart can beat “fast” and “irregular”. However, it is possible to have irregular heartbeats at an acceptable rate and not fast. This scenario is called “rate-controlled Atrial Fibrillation“, which means you have AF, but your heart is not beating fast.

Wht are some of the common causes of Atrial Fibrillation?

At birth, our Heart, like any other organ, is in pristine condition, but this starts to change with aging. Cardiac chambers (esp. the top chambers, called atria) can enlarge (dilate), or many specialised tissues can lose their capabilities, a process called degeneration. A few examples are the conduction system, which is specialised in conducting electricity, and cardiac muscle fibres, which contract in response to electricity. 

These structural and degenerative changes distort the electrical pathways, raising the likelihood of cardiac arrhythmias, including Atrial Fibrillation. Many comorbidities are known to expedite this process, including uncontrolled hypertension, diabetes, sedentary lifestyle and obesity, obstructive sleep apnea (OSA), smoking, excessive alcohol intake and genetic background. Of these conditions, age is the most important one and in general, the older you are, the higher the likelihood of developing Atrial Fibrillation. 

Is Atrial Fibrillation permanent or can it be cured?

Initially, AF happens periodically, called “Paroxysmal AF“. However, the episodes become increasingly more, and at some point, atrial fibrillation will be the dominant rhythm, called “permanent AF“. Medications and some specific procedures can temporarily control AF; however, there is no permanent cure for this condition, and once you have AF, you will always have AF.

How will AF affect you and your life?

Atrial Fibrillation is a chronic condition and can affect us in many ways. AF symptoms vary widely from person to person. Palpitations and general fatigue are the two most commonly reported symptoms. As the heart rate could be high with AF, minimal exertion can cause significant tachycardia, leading to significant exertional dyspnea. Some people might not even know that their hearts are beating irregularly and continue their everyday lives as if nothing has changed, while some patients cannot even tolerate very short episodes of AF.

Is it just about "symptoms" or can it be life-threathening?

Irregular heartbeat, per se, is not lethal, but when the heart beats irregularly, the chance of blood clots forming in the heart is quite high. If a large enough clot forms in the heart, it can move with the blood flow out of the heart. Where it goes usually? BRAIN, and if the clot is large enough to block a major artery, STROKE happens. Depending on how big the clot has been, the stroke could be trivial and temporary (TIA or Transient Ischemic Attack or “Mini-stroke”) or large and devastating or even lethal. But, the good news is that these days we have excellent medications to reduce the risk of stroke significantly.

Is managing AF is all about preventing stroke?

Of course NOT, but that is the most crucial aspect of management. The other important issue is to stop your heart from beating fast when in atrial fibrillation. The usual heart rate is 60 to 70 beats per minute. In AF, this could go up to anywhere from 80 to 170 beats per minute. If this continues for a long time, “heart fatigue” could happen, which is actually heart giving up, and that’s when heart failure comes into the picture. Heart rate control can usually be achieved by medications. So the two parts of managing AF are 1) Preventing stroke and 2) Controlling your heart rate.

I was told that my heartbeat should be regular, as that's how it's meant to be, isn't that true?

Well, that’s sort of true. The normal/regular heartbeat or “Sinus rhythm” can be achieved in two ways. Either with medications or via electrical interventions. The problem is that neither way is perfect. Unless you complain of some symptoms linked to AF, there is no significant point in reverting you to sinus rhythm as long as 1. you are protected against stroke and 2. your heart rate is within normal range and not fast.

What initial tests are usually recommended after diagnosing Atrial Fibrillation?

That largely depends on your complaints and symptoms. The routine initial tests, of course, after a physical exam, are ECG (Electrocardiogram) and an Echocardiogram. ECG shows how fast your heart is beating and establishes the diagnosis of Atrial Fibrillation and Echocardiogram shows how the heart is functioning and whether there is any underlying valvular disease causing the fibrillation. Depending on the other risk factors, assessment of the coronary arteries may also be required with a functional test like a stress echocardiogram. You require excellent control of all the risk factors for heart disease like Hypertension, high cholesterol and diabetes.

Two electrocardiograms showing showing the difference between sinus rhythm and atrial fibrillation. 

Sinus rhythm on Atenolol
1. Sinus Rhythm - Click to enlarge
ECG on Sotalol
2. Atrial Fibrillation - Click to enlarge