I Am A 68 Year Old Male With A History

I am a 68 year old male with a history of heart blockage and have had two bypass surgeries. I recently was in the hospital which they ran dye thru and discovered that one of my bypasses is now blocked but other valves are compensating for the flow and have been diagnosed with (I believe atrial tachycardia) irregular heart beat and was subscribed flecainide tab 100 mg 3 times a day. after speaking to pharmacists I am very concerned about taking this drug. I live alone and am some distance from medical emergency help. Should this drug have been administered while I was in the hospital and is rythmol a good alternative drug? What are the success rates with these drugs?