According to the British Heart Foundation, amongst others, smoking causes heart disease. I don't think even the most rabid smokers would disagree with this statement, but my short search of the internet failed to reveal any actual figures, although no doubt they exist. This does tend to suggest to me that they are actually quite low, so it is perhaps better not to actually mention them!
But this figure in today's Daily Mail is worth noting
Chantix, the No.1 anti-smoking drug in America, 'increases risk of heart disease by 72 per cent'
The drug is also associated with other reported side effect such as people trying to kill themselves, depression and unprovoked attacks on others.
So if you can't give up smoking without any chemical aids, it would seem that your best bet is simply to continue smoking, as I'm quite sure that smoking does not increase the risk of heart disease by anything like 72%.
I don't smoke, but I do object to the constant harassment of individuals whether they are smokers or drinkers by people who want to "improve their life". Sorry, my life would not be improved without my glass of beer or drop of Scotch, and I assume that smokers feel exactly the same about their cigarettes. We are aware of the risks, and it is our lives which are at risk; just leave us alone.