Metoclopramide (Reglan is the most common brand) affects a lot of neurotransmitters and neurotransmitter receptors throughout the body (dopmaine, acetylcholine, serotonin). Its primary use is to increase gastric motility (improve stomach emptying), in which case it works like acetylcholine to stimulate gastric smooth muscle to contract. It's very effective for that. However, in long-term use, the other effects on neurotransmitters can cause a bunch of disturbing side effects. The most common are movement disorders that resemble parkinsonism, due to metoclopramide blocking dopamine receptors, and another incapacitating and possibly permanent movement disorder called tardive dyskinesia. So, metoclopramide should be restricted to use for as short as possible and only when needed. I absolutely benefited from receiving it after my OHS, as my stomach was basically paralyzed by anesthesia for weeks. I took metoclopramide for a month, but stopped it as soon as possible when normal function returned. Since this drug fiddles with such basic parts of the autonomic nervous system, I would not be terribly surprised to hear it might have precipitated a cardiac arrhythmia. It's not one of the commonly listed side effects, but if you look around enough, you will find reports. The problem with reports of rare side effects is that they can be purely coincidental as nobody takes the risk to rechallenge and see if it happens again. So, sure it could be true in your case. Hard to say. Flutter tends to self-propagate once it starts. So, you may need some other treatment. And it would be advisable to find an alternative to metoclopramide for a lot of reasons, such as the other side effects I mentioned.
