AF Part 2

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Last week I discussed atrial fibrillation (AF), its causes, risk factors, and the use of blood thinners to prevent strokes, the most common problem caused by AF. Today I would like to review treatment of AF. The first way to prevent the development of AF and to make the return of a normal heart rhythm, or sinus rhythm, more likely is to lessen or improve the risk factors for AF. They are hypertension, diabetes, obesity, sleep apnea, alcohol abuse, and congestive heart failure. As mentioned last week, blood clots can form in the upper heart chambers, or atria, and are the cause of strokes associated with AF. Using blood thinners to prevent clots from forming decreases the risk of stroke. There are several types of blood thinners – Coumadin (warfarin), which interferes with Vitamin K in the series of steps known as the clotting cascade which causes blood to clot, agents that poison platelets and prevent them from sticking together and forming a clot like aspirin and Plavix, and agents that act on other proteins in the clotting cascade like Xarelto, Pradaxa, and Brilinta.

Treatment of AF focuses on two areas, namely rhythm and rate control. When initially diagnosed, a patient with AF is first placed on a medication to keep the heart rate controlled. The target heart rate is between 80 and 100. Medications like B-blockers (metoprolol), calcium channel blockers (diltiazem), and sometimes digitalis block the rapid electrical pulses from getting to the lower heart chambers, or ventricles. Once the heart rate is adequately controlled the next decision is whether or not to attempt to restore sinus rhythm. A number of factors are considered in deciding whether or not to attempt to restore normal heart rhythm and these include the patient’s age, other medical conditions, presence or absence of symptoms, and the patient’s preference. Converting AF back to sinus rhythm can be done in a number of ways. Methods include medications like sotalol and amiodarone, electrical cardioversion (using a defibrillator to administer an electrical shock to the heart while the patient is anesthetized), and catheter ablation where a catheter is threaded into the heart, which uses radiofrequency energy to burn the source of the abnormal electrical pulses.

Before attempting to convert the patient back to sinus rhythm, it is important to ensure that no clots have formed in the heart. This is done with both an echocardiogram and a trans-esophageal echocardiogram (TEE) where a scope is passed into the esophagus to look for clots. Converting a patient with a clot in the heart back to sinus rhythm will almost always result in a stroke. Newer procedures are coming forward like surgical removal or clipping of the atrial appendage (remember the pyramidal shape of the atrium), which will prevent clots from forming, thereby removing the need for blood thinners. New medications and procedures for treating AF are appearing frequently and although the number of people with AF is expected to at least triple the present number, hopefully treatment for these individuals will greatly improve.

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