Can you feel your tie putting some light pressure on your neck when you put it on? If not, it's not tight enough. And if yes, it's adding some constriction to your blood vessels, forcing your heart to work a little harder. Makes perfect sense for a guy with heart issues to not wear a tie in the situations where he would experience the most stress (like being down by 20 points at home to Oklahoma after losing two straight).
I'm hoping that you aren't being serious in any fashion.