Shelter Island Reporter medical column: What is A Fib?

We’ve all seen those TV ads during “Jeopardy!” for blood thinners with weird names for people with “A Fib.”

So, what is A Fib?

A Fib is short for Atrial Fibrillation, a condition in which the heart beats quickly and irregularly, often causing symptoms of palpitations, shortness of breath and fatigue.

The heart is basically a 4-chamber pump with its own electrical system that controls the heart rate (pulse) and coordinates the function of the two upper chambers (the atria) with the two lower chambers (the ventricles).

The electrical activity starts in the right atrium and is then conducted to the ventricles usually at a rate of 60-100 beats per minute (a normal resting pulse). In some people, the electrical impulses in the atria can become disorganized, causing them to beat irregularly (fibrillate), and resulting in irregular, fast pumping in the ventricles, with heart rates as high as 160 beats per minute.

These fast, irregular heart rates can lead to inefficient pumping of blood by the heart and to the symptoms described above. Some patients, however, may not have any symptoms.

The other potentially harmful result of A Fib is the formation of blood clots in the left atrium due to stagnant blood flow. These blood clots can then travel to the brain, causing a stroke.

What causes A Fib?

A Fib usually arises from abnormal electrical activity in the back of the left atrium. This occurs more frequently as people age and is more common in people with high blood pressure, dysfunctional heart valves, diabetes, congestive heart failure, coronary artery disease, thyroid disorders, chronic kidney disease, smoking, obesity and moderate-heavy alcohol consumption. It can also occur in younger adults with none of these conditions (“lone A Fib”).

A Fib is diagnosed with an EKG. Once A Fib is found, your doctor should refer you to a cardiologist. The initial evaluation will look for potentially treatable underlying causes such as overactive thyroid, which is detected with a blood test, and heart valve dysfunction or heart muscle dysfunction which are detected with an echocardiogram (heart ultrasound).

How is A Fib treated?

The two most important goals of treatment are slowing the heart rate and preventing blood clots in the left atrium, both of which are achieved with medication. Once the heart rate is slowed down and clot inhibiting drugs (anticoagulants) are given, most patients will feel much better and the risk of stroke minimized.

There are three kinds of anticoagulants. Coumadin, which has been around for 70 years, works by interfering with the production of clotting factors by the liver. Because its effect on clotting can be affected by other drugs, certain foods and alcohol, frequent blood tests are necessary to adjust the dose. Drugs like Xarelto and Eliquis work by directly inhibiting blood clotting factors; monitoring with blood tests is not necessary.

These drugs are generally safer, more effective and easier to take than Coumadin, but can be costly depending on your prescription plan. Drugs like aspirin and Plavix, which inhibit blood platelets, not clotting factors, are less effective than the others.

All of these drugs can slightly increase the risk of minor bleeding from cuts and bruises and more serious bleeding from the intestines, urinary tract and brain in patients with pre-existing conditions or head trauma. In most patients however, the benefit of stroke avoidance outweighs the risk of bleeding.

Do all patients with A Fib need to be on anticoagulants? The risk of stroke in patients with A Fib increases with age and other conditions like high blood pressure and diabetes. Younger patients (under 65) without other conditions have a low stroke risk and generally do not need to take these drugs.

Some patients do not tolerate anticoagulants because of recurrent episodes of serious bleeding or the risk of head trauma in elderly patients through recurrent falls. In those cases, your doctor may discuss implantation of a “Watchman” device.

This device is a small basket inserted in the heart  through a vein in the leg. It is designed to trap clots in the corner of the left atrium where they form and prevent them from traveling to the brain. As an invasive procedure it carries a risk of potential complications.

Although the device was approved by the FDA in 2015 and is often used, many cardiologists (myself included) feel the approval was rushed without adequate experimental evidence of its efficacy.

In some patients, the symptoms of A Fib cannot be adequately controlled with drugs. For those patients, there are several options. In a procedure called cardioversion, the heart is shocked back to a regular rhythm with external paddles under light anesthesia.

This procedure is usually effective, but the recurrence rates are quite high. Recurrence can be reduced somewhat by adding certain anti-arrhythmic drugs. A more durable but invasive option is a procedure called catheter ablation.  During ablation, small catheters are inserted into veins in the leg and threaded up to the heart, where they burn or freeze the electrical tissue in the left atrium that causes the A Fib. This procedure is successful in restoring and maintaining regular rhythm in 80-90% of patients. Of course, all invasive procedures carry risks of complications, which should be thoroughly  discussed with your doctor.

A Fib is a manageable disease. If detected and appropriately treated, most patients can continue to lead normal, active lives with minimal or no symptoms.

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