I Had A Heart Attack A Week And A Half

I had a heart attack a week and a half ago. I am 67 years old and really physically fit so I am bouncing back faster than normal. The cardiologist put me on 30 mg of imdur and it is causing headaches. I don't want to stop the imdur if my heart needs it but would like to stop the headaches. I read that some people have cut their imdur tablets in half and take half in the morning and half in the evening and it reduces the headaches without stopping the value of the med. My cardiologist is out until Monday so I can't ask him if this is OK. Do you recommend cutting them in half?