Features October 2017 Issue

Afib Causes Include Controllable Risk Factors and Structural Heart Problems

The more you can avoid high blood pressure, obesity, smoking, and binge drinking, the more you can lower your risk of the common heart rhythm problem atrial fibrillation.

Atrial fibrillation (afib) affects an estimated 2.7 million Americans, and is a leading risk factor for stroke and other cardiovascular problems. When a heart is in afib, the upper chambers (atria) beat chaotically and out of synch with the lower chambers (ventricles). This can cause blood to pool in the heart and form a blood clot. It can also put extra strain on the heart, putting you at a higher risk of heart failure.

Afib’s Risk Factors

But what are the causes of afib? Can you lower your risk of this dangerous heart rhythm abnormality (arrhythmia)? In many cases, lifestyle behaviors, such as smoking and binge drinking, may play a role in developing afib. For some people, poorly controlled high blood pressure is to blame. Obstructive sleep apnea, a disorder in which you stop breathing for a few seconds multiple times throughout the night, can also lead to afib if it’s not effectively treated.

But there are also problems with the heart’s structure that make afib a likely outcome. Some are unavoidable conditions from birth (congenital heart defects). Others stem from damage caused by a heart attack or other injury to the heart.

“Atrial fibrillation has many causes,” says Bruce Wilkoff, MD, director of Cardiac Pacing and Tachyarrhythmia Devices at Cleveland Clinic. He adds valve disease, stemming either from a congenital condition or from a degenerative problem, is an especially common cause of afib. Dr. Wilkoff also notes that high blood pressure and kidney disease can contribute to poor pulmonary vein health, including the formation of blood clots in your pulmonary veins. The pulmonary veins carry blood from the lungs to the heart to be pumped out to the rest of the body. It’s not uncommon for the pulmonary vein to carry extra electrical currents that trigger afib.

Afib Diagnosis

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“It appears that much of atrial fibrillation comes from impulses that originate in the pulmonary veins, and provoke the atrium into atrial fibrillation,” Dr. Wilkoff says. “Over time, this repeated stimulation makes the heart more and more vulnerable. By the time people get into their 90s at least one-third of them have some atrial fibrillation. Alcohol, particularly when abused, cocaine use, smoking, and less-severe structural problems—often after heart or chest surgery—causes atrial fibrillation to be more common.”

Pinpointing Causes of Afib

The cause of your afib isn’t always obvious. Chances are you may have more than one risk factor, such as advanced age, heart attack, valve disease, a history of smoking, obesity, high blood pressure, and a family history of afib or other arrhythmias. However, if there is an underlying cause, such as a leaking valve or hypertension, treating those problems will be essential to helping control your afib.

Interestingly, there is a form of afib called “lone atrial fibrillation.” People with lone afib have no heart defects or structural damage. Lone afib isn’t usually a chronic condition. It may be a one-time event or may appear intermittently. Some possible triggers for lone afib include overactive thyroid, binge drinking, caffeine, allergies or medications designed to prevent unhealthy rhythms, known as antiarrhythmic agents.

“Lone atrial fibrillation is common,” Dr. Wilkoff says. “It most commonly is related to impulses in the pulmonary veins in hearts that, for some reason, are more vulnerable to the initiation of the atrial fibrillation. It is less serious because, by definition, it is occurring in the setting of no other comorbidities (co-existing chronic diseases that can complicate one another). It is the comorbid conditions that increase the risk of a blood clot and stroke, and it is the comorbidities that make the choices for therapy more difficult.”

AAfib

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Atrial fibrillation occurs when the electrical currents in the heart cause the upper chambers to beat chaotically, instead of in their normal, synchronized pattern.

Treating Afib and its Causes

Treatment for afib includes medications, non-surgical procedures and surgery. Depending on the severity of your condition, medicines to slow your heart rate or put it back in a healthy rhythm may be your doctor’s first recommendation.

If medical therapy isn’t effective, the next step may be electrical cardioversion or a different procedure called catheter ablation. Electrical cardioversion uses electrical energy applied through paddles or patches from outside the chest. The hope is that a small electrical charge will reset your heart into a normal rhythm.

Ablation is done with a catheter inserted into a blood vessel and guided to the heart. The tip of the catheter can deliver radiofrequency energy to burn or destroy a tiny piece of heart tissue causing the afib. Ablation can also involve cryotherapy, which freezes the tissue. Catheter ablation is sometimes effective on the first try, though for many people, more than one procedure is needed. The two most common sites for ablation are the AV node, a cluster of cells that transmit electrical energy from the atria down to the ventricles, or the spot where the pulmonary vein enters the heart. This is called pulmonary vein isolation ablation.

Surgical solutions include an open-heart Maze procedure. During this surgery, a doctor makes a pattern of small incisions in your heart that resembles a maze. The scars that form should help interfere with the chaotic electrical patterns causing your afib. Another surgical option is the implantation of a pacemaker, a small electrical device to help keep your heart in a steady rhythm.

It’s also critical to treat any underlying causes of your condition.

“Going into atrial fibrillation is like being in a contest for normal rhythm, and at certain times the heart gets to a tipping point,” Dr. Wilkoff says. “If your oxygen level is chronically low due to sleep apnea, your valve leaks a bit, you binge drink alcohol, have uncontrolled hypertension, and if you are the person with many impulses coming from your pulmonary veins, then it isn’t certain when, but you will at some point go into atrial fibrillation. Depending on how significant these and many factors are, it may be earlier or later. Smoking, drinking, drugs, using continuous positive airway pressure (CPAP for sleep apnea), controlling blood pressure, stress etc. are all at least partially modifiable.”

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