I am 70 yrs old had a heart attack a year ago. Have a slow heart rate of 48 to 52 most of the time. I exercise and after reading all the reviews I am scared to take this. It was given to me for a bladder infection. My father died of cardiac arrest. The warnings that came with this tells me not to take it. My urine showed no bacteria. Sure feels like one though. What should I do call my heart dr? My family dr ordered it. 500 mg for 7 days.