After doing some brief research online it appears choline can have an effect on the electrical system of the heart, there are several medical papers online that discuss this topic, however I'm not medically savvy enough to decipher exactly what's going on there.
Some examples of what I came across:
Is there any reason why someone prone to tachycardia should avoid supplementing with a standard dose of Choline (300mg)? Alpha-GPC for example, or Choline Bitartrate. Would there be any risk of inducing tachycardia due to the Choline supplement?