I am 15 wks post op and doing and feeling great. I have finishined 19 cardiac rehab sessions. On Monday after my 18th session, my rehab lady (title?) said that I was having extended periods of QRS--spikes on my EKG--(something to do with the heart's electrical current). She had noticed a small amount of this previously when I was on the elliptical but then it stopped when I went on to other equipment. However, on Monday it continued thru my workout. She said she would fax copies of the EKG to my cardiologist. Today at my 19th session I asked if she had heard anything back from my cardiologist--and she had not. I decided to skip the elliptical today and just do 30min of treadmill and 12 minutes of windjammer and then weights. I didn't have any of the QRS. I'm not sure if this is something I should worry about. Possibly I was doing too much too soon--I was up to 12min on the elliptical? Has anyone else experienced this?