Thanks for your question on Healthcare Magic.
I can understand your concern.
Since you are active smoker, we should definitely rule out heart diseases (
arrhythmia - rhythm disturbances in heart) for your symptoms.
So get done ecg, 2d echo,
stress test and Holter monitoring (24 hours continuous recording of Ecg).
If all these are normal then no need to worry for heart diseases.
Sometimes undiagnosed stress and
anxiety can also cause similar symptoms.
So avoid stress and tension, be relax and calm.
Quit
smoking as soon as possible because it is not good habit.
Hope I have solved your query. I will be happy to help you further. Wish you good health. Thanks.