If you drink caffeinated black coffee, a recent study says you could be helping your heart.

A new study from the American Heart Association, which was published Tuesday in the American Heart Association journal Circulation: Heart Failure, found that the more cups of coffee drank, the risk of heart failure fell by 5%-12% per cup of coffee a day.

"The association between caffeine and heart failure risk reduction was surprising," senior author Dr. David Kao said in a news release. "Coffee and caffeine are often considered by the general population to be 'bad' for the heart because people associate them with palpitations, high blood pressure, etc. The consistent relationship between increasing caffeine consumption and decreasing heart failure risk turns that assumption on its head."

Researchers analyzed data of more than 21,000 Americans from three studies: Framingham Heart Study, the Atherosclerosis Risk in Communities Study, and the Cardiovascular Health Study.

According to the studies, although caffeine is consistently associated with reducing heart failure risk, caffeine in large amounts can be dangerous.

Researchers found that decaffeinated coffee significantly increased the risk of heart failure.