Senior analyst Didier Garriguet and colleagues at Statistics Canada measured the association between daily smoking and the risk of heart disease for more than 10,000 men and women using 16 years of data up to 2011.
"Among individuals who continue to smoke, cutting down the number of cigarettes smoked also reduced risk," Garriguet told the CBC.
Current daily smokers were 60 percent more likely to have been diagnosed with, or to have died from, heart disease than were people who had never smoked daily, Garriguet said.
The study, published in the agency's journal Health Reports, said the finding that after 20 years of continuous smoking cessation people returned to the same risk levels of those who never smoked was in line with the U.S. surgeon general's finding of 15 years -- although Canadians tended to smoke fewer cigarettes than in other studies.
A related study released by the Statistics Canada found the sooner people quit smoking, the better the chances of eventually gaining the same health quality of life as non-smokers.