Two months into new pacemaker. All was well until first tune up one week ago. Heart now regularity missing beats. Seems to be worse when I exercise (hiking) --so much so that I need to slow way down and take it very easy. I m 68, told I have a strong heart, regular exerciser by hiking the mountain near our home. Booked in for full tests late next week. My question--should I be concerned enough to get looked at right away ? Thanks for this service.