A few weeks ago my friend had a physical and the doctor said he had a atrial fibertion (an irregular heartbeat) and sent him to a cardiologist. The cardiologist put him on a Halter monitor for 24 hours and said to do what he normally did. The next day called for hills so he did them. My friend has been doing hills, tempo and long runs ever since including 24 miles a couple weeks ago and reach the beach last Sunday. (and he is still alive)
Today, the cardiologist tells my friend to not run because of a Y complex tachycardia until after he has a Cardio CT scheduled for Tuesday. The problem for my friend is he is running Boston in a couple weeks and this weekend is the last chance for a long run. He thinks he can do a long run on Sunday since he has been running this long without a problem.