DEAR DR. ROACH: I’m writing about atrial fibrillation. In April I had a one-time 17-hour stint of it. I was not aware of anything happening at the time. When I had a device check (heart pacemaker), I was told of this occurrence, and it was recommended that I see my heart specialist. As a result, I was given the choice of taking Eliquis. It was highly recommended. I purchased some, but did not take any of these pills because of the warnings on TV that this medication “can cause a stroke, bleeding risks,” etc. I also have had an aortic valve replacement (I had a bioprosthetic valve), and they recommend I do not take this pill. — P.A.

ANSWER: Atrial fibrillation is a common condition, especially in older people, where the rhythm of the heart is disrupted. This can cause symptoms due to an irregular heart rate (palpitations), exercise intolerance or shortness of breath (especially if the heart rate is too fast), but it doesn’t always cause symptoms.

Even without symptoms, atrial fibrillation is concerning because it increases the risk of blood clots. Without coordinated rhythm, the blood in the atria (the top chambers of the heart) can form clots, which then can get carried in the bloodstream up to the brain. There they cause a stroke. The risk of stroke in a person with atrial fibrillation depends on age, sex and other factors, but it is something like 3 to 5 percent per year. With medication, such as apixaban (Eliquis) or warfarin (Coumadin), that risk is much reduced, by about two-thirds.

These medicines work by making it a little harder for the body to form clots. A side effect is that it makes the body a little bit more likely to bleed. Bleeding inside the brain also may cause a stroke, hence the warnings you read and hear for medicines like Eliquis. Still, with medication there is a large net reduction in stroke risk, and if your cardiologist has recommended it, it’s because the cardiologist has reason to think that in taking it, there is more benefit than harm for you.

People with mechanical heart valves are at risk for developing clots and then strokes. Eliquis and other new treatments are not effective for people with mechanical heart valves, and Coumadin remains the best choice for nearly everybody with these kinds of valves. Since you don’t have a mechanical valve (yours is made from pig tissues), you don’t have an increased risk of stroke due to the valve. The valve doesn’t change the fact that you would benefit from treatment of the atrial fibrillation.

DEAR DR. ROACH: My 74-year-old husband was recently diagnosed with Stage 3B kidney failure. We want to do whatever we can to preserve his kidneys. We are confused though. The information we find on the internet recommends a strict diet, but his nephrologist said recent information indicates that diet doesn’t matter. Please enlighten us. — S.S.

ANSWER: Kidney function reliably decreases with age, and many older adults are confused after getting a new diagnosis of “kidney failure.” But the term applies to many people whose kidney function is as expected for their age. In other words, many healthy older adults whose kidney function is as expected for their age are now being classified as having kidney failure. I suspect that’s why your husband’s kidney doctor isn’t restricting his diet. I hope, though, that the doctors have looked carefully at his medication doses; they sometimes need to be adjusted.

There is good evidence that eating less meat and more plants can slow the progression of kidney failure.

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Dr. Roach regrets that he is unable to answer individual letters, but will incorporate them in the column whenever possible. Readers may email questions to ToYourGoodHealth@med.cornell.edu or send mail to 628 Virginia Dr., Orlando, FL 32803.

Dr. Roach