... MICKXXXY. Self diagnosed refered to Papworth by my Dr who put me on rivaroxaban 20mg when I feel a flutter it only lasts for a split second I am a very fit 72 year old (treadmill every day) plus I have a very slow pulse rate (35/40 at rest)which I thought was because of being fit.my doc says the benefits far out way the side effects I sincerely hope so because the list of side effects are really frightening I would like to know when if at all the side effects will start MICKXXXY