Sudden increase of heart rate following fears and worries?

there are three things you should change. If you can,then worries and fear wear out. First, please stop smoking. I know it's not easy to do it if you are dependent to it but trying to quit helps. Second, do exercises. there are several ways to do it. play basketball, walk 30 minutes or more a day, do household chores, stretch your legs. these would give you good blood circulation and more benefits. third, eat proper diet on time. I am a heart patient and I have been living healthy life since I quit bad habits and exercise regularly. at first I kept on thinking about my condition that gave me more stress. when I decided to live my life with a healthy lifestyle, it changed everything. no more worries, no fear. above all, pray and pray.

It sounds like you might have an issue with your adrenal glands. Adrenaline makes your heart beat faster, and typically fear results in a rush of adrenaline. Maybe there's something triggering the fear response and that triggers the adrenaline rush. I'd see a doctor. The biggest concern is that the fears are general, like a kind of generalized anxiety.