I've taken Ranitidine sporadically for years, and have never associated it with arrhythmia. However, the perhaps reason you're taking Ranitidine, namely GERD has been associated with arrhythmia. Interestingly, the day I cut as many carbohydrates from my diet as I could was the last day I needed to take Ranitidine.
Have a sensitive stomach and get burning pains especially if food has chilly or is strong in acid. Ranitidine has helped but from time to time suffer missing hearbeats. Having given up the drug for a while things improved but stomach started to suffer again and thus the reason to re-start the drug.
to tom h
thanks for the comment