Chest pain, palps, cough, rapid heart beat. all negative mri/a, ct, echo, ecg, xray, bloods. but symptoms improve with diltiazem tildiem. what is it?

Arrhythmia: Arrhythmia or an abnormal heart rhythm will improve with Diltiazem. You may need a Holter monitor trying to understand if that' s the case.

Likely benign: I'd likely use up to 25 mg 3X/day of Lopressor (metoprolol tartrate) on an as necessary basis t control symptoms. 1st do 14 day event recorder to identify the arrhythmia (irregular heartbeat). See www.thepmc.org website. HRS, MD, FACCO