Why atrial fibrillation occurs
Atrial fibrillation, or afib, is the most common heart arrhythmia in the world. It is an irregular and often rapid heartbeat that can lead to blood clots and stroke. Unfortunately, there are more people than ever before living with afib and it has been estimated that by 2030, 12.1 million in the United States alone will be living with atrial fibrillation. Research tells us that more than half of these cases could be prevented by optimizing several risk factors. Let’s cover today what exactly atrial fibrillation is - with a particular emphasis on why atrial fibrillation occurs and what we can do to prevent it
What is atrial fibrillation?
Atrial fibrillation is a specific type of irregular heartbeat, or arrhythmia, where the upper chambers of the heart (the atria) quiver in an irregular fashion instead of filling and squeezing in the normal coordinated fashion. Often the heart beats quite rapidly, but the heart could beat faster or slower than an individual’s baseline. Normally, the contraction of the atria and the lower chambers, the ventricles, are coordinated by the natural conduction system. However, in atrial fibrillation, instead of coming from the heart’s natural pacemaker (the sinoatrial node), the electrical impulses are coming from several different foci in the atria.
This irregular heartbeat means that the blood isn’t pumped out from the atria to the ventricles quite as smoothly and efficiently. With these irregular beats, there is increased risk of blood stagnating in the atria - this can lead to clots forming in the heart, which can travel to the brain and lead to stroke. Afib increases the risk of ischemic stroke by about 5 times. In addition, there is a correlation between atrial fibrillation and heart failure.
For some people, atrial fibrillation is episodic or paroxysmal, with long intervals between episodes, and for others, it is consistent and permanent - this usually occurs after it has been present for some time.
Symptoms of atrial fibrillation and diagnosis
Not everyone with atrial fibrillation experiences symptoms, but symptoms can include palpitations, chest pain, lightheadedness, fatigue, passing out (syncope), and shortness of breath.
The diagnosis of atrial fibrillation is made when your doctor sees evidence of atrial fibrillation on an electrocardiogram, with it’s characteristic irregular appearance. Often blood tests will be done to rule out thyroid disease, electrolyte abnormalities and other potential underlying causes. An echocardiogram will also often be performed to check on the pump function of your heart and rule out valvular heart disease.
Risk factors for atrial fibrillation
Risk factors for afib include many that are nonmodifiable - meaning you can’t do anything about them - and others that are modifiable.
The biggest risk factor that we can’t change is our age, as well as several chronic conditions like lung disease, valvular heart disease, heart failure, or ischemic heart disease. Family history of atrial fibrillation is also a risk factor for developing atrial fibrillation that is obviously not modifiable. Other risk factors can potentially be changed including hypertension, obesity, diabetes, smoking, sleep apnea, hyperthyroidism, stress, and alcohol use.
Common triggers for an atrial fibrillation episode include infection/fever, excessive caffeine, stress, alcohol, and very strenuous exercise.
Skip down to the next section if you want to learn more about these factors and how to prevent atrial fibrillation!
Treating atrial fibrillation
Managing atrial fibrillation has a two pronged approach.
The first priority is discussing stroke risk and stroke management. If you have atrial fibrillation and you want to know your estimated risk of stroke, you can calculate it here. The CHADS-Vasc score will give you an estimated risk of stroke, and then show you how it decreases on treatment - namely blood thinners. For young people with no risk factors, typically no blood thinners are recommended. For those with several risk factors, treatment often involves the use of coumadin, or more likely, one of the novel anticoagulants. For those who have a very high risk of bleeding, newer devices such as the Watchman are available that can help minimize the risk of stroke.
The other equally important consideration is that of symptom control. While traditionally, many would be placed on medicines that control heart rate (such as beta blockers or calcium channel blockers) or medicines that control heart rhythm (such as amiodarone), increasingly atrial fibrillation ablation is being recommended. This procedure electrically cauterizes the foci that are emitting the abnormal heart rhythm, and in good candidates, can have a very high success rate
Lastly, an important and often neglected tool in afib management is lifestyle adjustments aimed at those modifiable risk factors if they are present. This means diagnosing and treating hypertension, sleep apnea, and diabetes, smoking cessation, minimizing alcohol, and weight loss if above the ideal body weight. The 2019 updated guidelines emphasize the importance of addressing these risk factors - the so-called fourth pillar— and recommend leveraging medications and lifestyle modifications (e.g., diet, exercise, stress management) as necessary. Of note, these guidelines specifically addressed weight loss, highlighting research that has found that weight loss if indicated can result in better symptomatic control.
How to prevent atrial fibrillation
Research has shown that more than half of all cases of atrial fibrillation are potentially avoidable with the optimization of several risk factors. While nothing can guarantee you won’t get atrial fibrillation - and there is certainly a genetic component - there are steps you can take to minimize chances of developing atrial fibrillation in the first place. And if you already have atrial fibrillation, working on treating some of the underlying causes may help reduce your burden of symptoms
Hypertension - high blood pressure contributes to more cases of afib than any other risk factor. It has been estimated that hypertension is the main contributor of about 1 in 5 new cases of Afib. If you have high blood pressure, work with your doctor to get it under control with lifestyle changes (I write about this here) and medications if needed
Sleep apnea - both obstructive and central sleep apnea is associated with the development of afib. Those with sleep apnea have a 2 to 4-fold higher likelihood than those without it of developing afib, and some afib treatments have been shown to be more effective in patients whose sleep apnea is being treated. If you have symptoms of sleep apnea (such as snoring, gasping or choking in your sleep, excessive daytime sleepiness), consider asking your doctor for a sleep study - they can now be done from the comfort of your own home!
Stress - while exact mechanistic links between stress and cardiovascular disease remain ill-defined, emerging evidence suggest that stress is associated with the initiation and potentiation of atrial fibrillation. Chronic stress is linked with a heightened sympathetic tone, inflammation, vasoconstriction, and oxidative stress - all of which are drivers of atrial fibrillation. While there is no evidence to date that treating chronic stress reduces risk of atrial fibrillation, studies have shown mindfulness based stress reduction, yoga, and meditation can reduce intermediaries like hypertension
Alcohol - alcohol use can increase your risk of atrial fibrillation. While we have long known that excessive, or binge drinking, can result in atrial fibrillation - known as holiday heart syndrome - some research has shown that even one glass of alcohol is associated with twofold greater risk of atrial fibrillation over the next several hours. Minimizing alcohol ingestion, especially large quantities, should be considered - particularly for those who are at risk for atrial fibrillation or already have it
Weight management and metabolic health - for those who are above ideal body weight, treatment is a critical part of managing atrial fibrillation and likely preventing it as well. Obesity is associated with cardiac remodeling (changes in the structure of the heart) that predispose to developing atrial fibrillation. Studies have shown that structured lifestyle programs to treat the excess adiposity results in a reduction in episodes of atrial fibrillation. Structured weight loss programs, with or without the use of novel weight loss medications, should be considered if indicated.
The skinny on atrial fibrillation
Atrial fibrillation is an abnormal heart rhythm that can cause uncomfortable symptoms such as palpitations, lightheadedness, or shortness of breath, and can increase the risk of stroke. While the cornerstone of treatment remains symptom control, either with medications or procedures, and mitigation of stroke risk - the conversation must also include that of prevention. This can mean primary prevention, ie treating risk factors before atrial fibrillation develops, or secondary prevention, ie working on risk factors to reduce symptomatic episodes. If you already have atrial fibrillation, working with your doctor to reduce your burden of symptoms by treating the underlying causes with lifestyle management should be part of a comprehensive strategy in atrial fibrillation treatment. With few exceptions, it is often not able to be “cured,” but with the right care, people with atrial fibrillation can lead long, healthy, and active lives.
Interested in working with a preventive cardiologist to manage your atrial fibrillation?
