DEAR DR. ROACH: I’m a generally healthy 60-year-old man. Last week, I had some abdominal cramping, and while I was on the toilet, I noted the abrupt onset of a strange feeling in my chest as well as abnormal, irregular and fast heartbeats. My watch has an electrocardiogram (EKG) function, and it immediately said I was in atrial fibrillation at a rate of 100-130 bpm.

I went to the emergency room where they confirmed AFib, did a bunch of blood tests, and gave me a dose of IV diltiazem to slow my heart rate down. After about 5 hours, my heart rhythm went back to normal, and they let me go home. I’m to see the cardiologist next week and have an EKG.

My question is whether the abdominal cramps could have caused me to go into AFib. — I.J.M.

ANSWER: AFib, an irregular and often fast heart rhythm, is common and has several well-known risk factors that precipitate an event. The ER will have considered several of these, including thyroid disease (especially too much thyroid hormone), pulmonary embolisms, and heart attacks. The EKG is to look for structural heart disease. Sleep apnea and excess alcohol use may also precipitate AFib. However, it is possible to develop AFib without any known risk factors.

One system that is not commonly considered as a precipitant of AFib is the gastrointestinal system, but there are many reports of gastrointestinal conditions being associated with a new onset of AFib. The heart is very well-supplied with nerves that are part of the autonomic nervous system, and there are many case reports of AFib starting at a time of high stimulation of the parasympathetic nervous system (the “rest and digest” mode of the autonomic nervous system), as is seen in people with abdominal cramping or reflux.

It may be hard to separate cause from effect as people with AFib are more likely to develop gastrointestinal issues, but your story of severe cramps just before the onset of AFib is suggestive that in your case, the abdominal cramping may have started your AFib. It’s known that receptors in the heart muscle respond to the parasympathetic neurotransmitters, making it more likely for AFib to develop.

In addition to trying to find any underlying cause, cardiologists consider whether to treat people who have AFib with medication to keep the heart rate in a normal range (like the diltiazem they gave you). They also consider whether to use treatment (medication or electricity) to get and keep people out of AFib and consider treatment to prevent a stroke. This is a big concern in people with AFib as they are much more likely to develop blood clots in the heart that can go to the brain.

If you stay out of AFib, this may not be necessary for you, but your cardiologist may order a device to watch your heart rate continuously to see if the AFib comes and goes. If you do have periods of AFib, your cardiologist will likely prescribe medication to reduce your stroke risk, as people who go in and out of AFib are also at risk for stroke, just like people who are in AFib all the time.

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.