One year after passing smoking bans, communities in North America and Europe had 17 percent fewer heart attacks compared to communities without smoking restrictions, and the number of myocardial infarctions (MI) kept decreasing with time, according to a report in Circulation: Journal of the American Heart Association.

The report is a meta-analysis of 13 studies in which researchers examined changes in MI rates after smoking bans were enacted in communities in the United States, Canada and Europe. The researchers found that MI rates started to drop immediately following implementation of the law, reaching 17 percent after one year, then continuing to decline over time, with about a 36 percent drop three years after enacting the restrictions.

"While we obviously won't bring heart attack rates to zero, these findings give us evidence that in the short- to medium-term, smoking bans will prevent a lot of heart attacks," said James M. Lightwood, Ph.D., co-author of the study and assistant adjunct professor in the department of clinical pharmacy at the University of California-San Francisco. "The studies on this issue now have long enough follow-up periods so that we can see exactly how big the effect is."

Lightwood also noted that the community effect is consistent with probable individual risk and exposure scenarios.

For example, according to the American Heart Association's Heart Disease and Stroke Statistics 2009 Update, non-smokers exposed to secondhand smoke at home or at work have a 25 percent to 30 percent increased risk of developing heart disease. This new research suggests that the individual increased risk may be higher, said Lightwood.

"This study adds to the already strong evidence that secondhand smoke causes heart attacks, and that passing 100 percent smoke-free laws in all workplaces and public places is something we can do to protect the public," Lightwood said. "Now we have a better understanding of how you can predict what will happen if you impose a smoking-free law."

David Goff, M.D., Ph.D., Chair of the Department of Epidemiology and Prevention and Professor of Public Health Sciences and Internal Medicine at Wake Forest University School of Medicine in Winston-Salem, NC, and an American Heart Association national spokesperson said the paper provides strong support for the contention that smoke free laws will improve public health. "This is good evidence that the benefits are realistic and consistent with reasonable estimates of the harm imposed by secondhand smoke," Goff said.

"It is important to move forward now with widespread implementation of smoke-free laws," he added. "At a time of great concern over the financial sustainability of our healthcare system, smoke free laws represent an inexpensive approach to reducing heart attacks, and, probably, other cardiovascular conditions."

Stanton Glantz, Ph.D., co-authored the study. The National Cancer Institute funded the study.