A fib, according to the dictionary, is a lie.
But to physicians and millions of patients, A Fib is also shorthand for Atrial Fibrillation, one of the commonest and most important abnormalities of the rhythm of the heartbeat. And new data show us that one of the most clinically significant things we have been saying about A fib may be a lie.
A Fib is characterized as an irregularly irregular rhythm. In other words, it’s sort of chaotic, with no recognized pattern to the disturbance in the normally rhythmic beating of the heart. In A Fib, the specialized cells in the right upper heart chamber (right atrium) lose their ability to generate a regular electric signal that should travel down to the pumping chambers of the heart (ventricles) and cause the heart muscles to contract producing a heartbeat and a pulse. Instead, the upper heart chambers (atria) are subjected to perhaps hundreds of random electric signals, only a variable fraction of which get transmitted through special electric channels to the ventricles, because these special transmitting channels are unable to process and deliver all of the signals coming to them.
As a result of the constant barrage of electrical activity in the atria, the atrial muscles cannot contract and pump blood to the ventricles. Instead, the atria merely quiver, and while some blood flows into the ventricles anyway, a lot tends to stagnate and pool within the upper heart chambers. And when blood pools, it tends to clot, and therein lies the most serious issue with A Fib.
If clots that formed in the stagnant pool of blood in the atria stayed there, it would not be too much of a problem. But if a clot travels to the ventricles, it can then be pumped out of the heart. The right ventricle pumps blood to the lungs, but the left ventricle pumps blood around the body to all the organs and tissues. The consequences will vary, depending on where a clot travels and lands in its journey from the heart. While clots can land in almost any organ, the most serious outcomes arise when a clot travels to the brain.
In this circumstance, if a clot blocks a blood vessel in the brain and prevents blood flow from reaching the vulnerable brain tissue, the result is a stroke, one of the most feared of human ailments. Brain tissue, like other body tissues, requires the delivery of fresh blood with oxygen to maintain its function. Deprived of this blood, brain tissue will be seriously injured, and brain cells will die. Depending on where in the brain the blockage of blood flow occurs, and whether there are auxiliary blood vessels to help bring blood to the affected area, the results may be weakness or total paralysis of parts of the body, and loss of the ability to speak. If the brain injury is extensive enough, the patient may even die.
In the feared world of stroke, A Fib is one of the most common causes of brain injury due to blocked blood vessels. Preventing stroke should be the first order of business, the top priority, in dealing with a patient with A Fib. And considering that millions of people worldwide have A Fib, including millions in the United States, there are a lot of strokes to be prevented. And here is where things get somewhat complicated, because stroke prevention in A Fib is not a “one size fits all” proposition. There are a few ways to approach the problem, and there is no universal agreement on which way is best.
The first question to be answered is whether every patient with A Fib is, in fact, at risk for a stroke. This is important because every preventive strategy has its risks and downsides, so if a patient in A Fib were not at risk one could avoid trying to prevent a stroke. To answer the question, physicians have developed so-called risk scores in an attempt to decide who is at risk. The risk factors included in the scoring systems include age, gender, the presence of diabetes, heart failure, hypertension (high blood pressure), and vascular (blood vessel) disease. Each risk factor gets a numerical value and the total added-up score determines actual risk, The higher the score, the greater the risk; of course, the score is hardly precise for any single individual, but it at least provides a guideline for patients and physicians to consider when discussing stroke prevention efforts.
Once “risk” is calculated, and the level is high enough to warrant preventive action, there are several options. The most widely used strategy is to prevent clots from forming in the heart by administering drugs that do just that. They prevent clot formation and are known commonly as “blood thinners,” although the blood is not actually thinned. There are a variety of such drugs available, and each has its benefits and drawbacks. They all, of course, share the risk of causing what might be thought of as the opposite of clotting, that is, bleeding. And there are risk scores for bleeding, too, that physicians and patients need to be aware of as they balance risks and benefits.
Another strategy for stroke prevention is restoration of the normal heart rhythm, that is, eliminating A Fib altogether. This sounds exactly right: Get rid of the problem itself. The difficulty with this is that it is not easy to permanently restore the normal heart rhythm. The two main methods of trying to reestablish normal heart rhythm are medications and an invasive technique called ablation. The drugs are only partially effective and carry risks of provoking abnormal rhythms while trying to abolish them. Ablation, which has become an exceedingly popular means of addressing A Fib requires placement of special catheters inside the heart and ablating or destroying the abnormal electrical circuits that maintain the A Fib. There are several ablation techniques, and different cardiac electrophysiologists (cardiologists who deal with electrical disturbances within the heart) have different preferences.
The rise in popularity of ablation was originally largely due to the belief that it was a permanent cure for A Fib. And that meant no need for “blood thinners” and the risk of bleeding from the drugs. That turns out to have been wrong. While the likelihood of A Fib recurrence is reduced, it is not eliminated, and the frequency of recurrent A Fib is often enough to require “blood thinners” anyway.
The problems with “blood thinners” are worrisome enough that another technique for dealing with the stroke risk in A Fib was developed. This involves an invasive procedure whereby a device is placed within the left upper heart chamber that basically surrounds and closes off the area within that heart chamber where clots mostly form and prevents them from moving into the left ventricle to be pumped out around the body. This technique is especially useful in patients who, for one reason or another, cannot or will not take “blood thinners” to prevent clots. But it is far less frequently done than ablation which has become almost the standard of care.
Once the need for continued use of anti-clotting drugs even after ablation was understood, some of the luster around the procedure was tarnished. Since A Fib could recur, and “blood thinners” were often still needed, proponents of ablation touted an improvement in Quality of Life (QoL) as the main justification for the procedure. In fact, guidelines recommend catheter ablation for symptom relief in patients with atrial fibrillation, and no one has challenged that assumption until very recently.
QoL, one realizes, is a largely subjective term, based on a person’s symptoms, sense of well-being, and overall satisfaction with life. But like many things in medicine, it was too vague to stand alone, so other kinds of scores were developed to try to measure this somewhat nebulous concept. One such scoring instrument is known as the Atrial Fibrillation Effect on the Quality-of-life Questionnaire (AFEQT). And in a paper just published in the reputable journal Lancet, ablation failed to show an improvement in QoL according to the AFEQT summary score.
If the need for “blood thinners” persists even after ablation because of recurrent A Fib, and If Quality of Life is no longer a provable benefit of ablation — if that is a lie about A Fib — is there still a strong argument for ablation as the preferred method of treating A Fib?
I don’t know the answer, but it’s worth a discussion with your physician if you are facing that situation.
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