I was told that because of the vagus nerve that gerd can cause a fast heart rate. is that true?

GERD: A rapid heart rate is not in general a part of gastroesophageal reflux disease syndrome. The vagus nerve does have a proximity to the area but is not usually affected by what is going on with esophageal reflux.

Endothelial Problem: Heavy meals can cause the cells covering the interior wall of arteries to become sluggishly and sticky, a condition called endothelial dysfunction. This leads to decreases blood supply to the organs. In your case, the heart. The heart rate increase due to the increased demand without the appropriate supply of blood.