Well beta blockers are generally the first line treatment for PVCs, that's why he tried to give them to you. I'm not sure why he would give you Xanax unless he thinks it's anxiety related. Bottom line PVCs are generally considered to be benign in people with structurally normal hearts, so until you get an Echo cardiogram it's really hard to say if it is serious or not. I would assume the ER doctor did some basic tests and an ECG.