I have been on propranalol for many years. It reduced missing heartbeats,my life has been normal. Recently, having a lot of missing beat in the evening. A stress test showed no problems. we have added motoprolol... No more missing beats. However, The issue of out of breath with minor excertion has never been addressed. I noted that my pulse disappears when first exert myself, but returns to normal in about 30 seconds. Then I can continue to excert without breathlessness. Should I worry about this.? Walter Fraedrick