What Are The Risk Factors for Atrial Fibrillation?

It is important to remember that atrial fibrillation is a problem with the electrical system, or the "wiring" of your heart. It is not the same as a heart attack, and it is not necessarily related to the "plumbing" of your heart, the coronary arteries. When we talk about "risk factors" for atrial fibrillation, we are not talking about the same risk factors that affect your chance of angina and myocardial infarction (heart attack) such as high cholesterol and smoking. While it is very important to have a healthy diet, not smoke, and exercise regularly, many patients with atrial fibrillation are frustrated because they have done what they can to reduce their risk for coronary disease, but they still have atrial fibrillation. Unfortunately, our knowledge of the specific risk factors (such as diet) for most cases of atrial fibrillation lags far behind that of coronary disease. Be assured, however, that we are working hard to answer one of the most common questions patients with atrial fibrillation ask: Why me?

While the specific cause in every case may not be known, studies have shown that atrial fibrillation may accompany a number of other medical conditions. For example, some of the known risk factors and associated factors for atrial fibrillation include:

• More common in men than in women
• High blood pressure
• Advancing age
• Coronary heart disease, with or without previous heart attack
• Abnormal heart muscle function, including heart failure and cardiomyopathy
• Mitral valve disease
• Overactive thyroid
• Low amounts of oxygen in the blood from chronic lung disease
• Inflammation of the lining surrounding the heart (pericarditis)
• Blood clots in the lung (pulmonary embolism)
• Excessive alcohol intake
• Stimulant drug use (decongestants, caffeine, cocaine)
• Recent heart or lung surgery
• Electrolyte imbalances in the blood, especially low potassium level
• Diabetes
• Tachycardia - bradycardia rhythm disturbance (sick sinus syndrome)
• "Vagal" atrial fibrillation, sometimes in conditioned athletes

While atrial fibrillation itself may not be immediately life-threatening, there are several reasons why it still should be treated:

• Decrease symptoms and increase activity tolerance
• Decrease the risk of stroke
• Prevent the progression to chronic atrial fibrillation
• Prevent the wearing out of the ventricular heart muscle

Even if your symptoms are barely noticeable, atrial fibrillation may have serious consequences when left untreated. People with atrial fibrillation have mortality rates twice as high as those with normal sinus rhythm, even with all other cardiac risk factors being the same. Studies have shown that prolonged episodes of atrial fibrillation lasting several months or longer can cause weakening and "stretching" of the heart muscle, reducing the ability of your atria to contract. Congestive heart failure occurs when there is extra volume of blood backing up in your system due to the heart's inability to contract effectively and create enough of a forward flow. The physiologic stretching of the heart chambers can also lead to decreased ability of your conduction system to maintain a normal sinus rhythm, known as the electrophysiologic "remodeling". This remodeling process is known to begin after just a few hours of being in atrial fibrillation.

Perhaps the most serious complication of any patient developing atrial fibrillation is stroke. As discussed earlier, during atrial fibrillation, the quivering atria are very inefficient at pumping blood to the ventricle. As a result, some blood remains in the atrium too long, and clots (thrombi) can begin to form in this stagnant blood.

If a clot (embolus) breaks loose and is carried into the blood stream, it can travel anywhere in your body, blocking blood flow to your arms, legs, internal organs, etc. The risk of such an embolic event is almost 18 times greater in people with atrial fibrillation than in the general public. The most devastating complication occurs when a clot is carried into the arteries serving your brain, causing an embolic stroke. The American Heart Association estimates that 80,000 strokes per year in the U.S. are related to atrial fibrillation. Patients who suffer from atrial fibrillation are five times more likely to experience a stroke than those with normal heart rhythms.

While atrial fibrillation itself is usually not an immediate life-threatening and debilitating disease, it deserves careful monitoring and treatment to eradicate symptoms and to prevent its potentially devastating complications.