According to a study in the September issue of the journal Epidemiology, some people could get a heart attack within one hour of having a cup of coffee. There was a risk of almost 60% amongst moderate coffee drinkers, but the risk just quadrupled for those who drank less than a cup per day. Nothing much happened to heavy coffee drinkers.
The patients with other risk factors like, diabetes, obesity, heart disease, and hypertension were twice prone to heart attacks with coffee drinking. This has led researchers to summarize that those who consumed coffee occasionally are not used to the effects of caffeine. Therefore it is better that people with coronary heart disease who drank coffee rarely, avoided coffee completely.