Indoor smoking bans substantially cut heart attack rates in communities and may have an impact on sudden cardiac death as well, a population-based study showed.
Myocardial infarction (MI) incidence dropped 33% after implementation of ordinances banning smoking in restaurants and the workplace, Richard D. Hurt, MD, of the Nicotine Dependence Center at the Mayo Clinic in Rochester, Minn., and colleagues found.
Sudden cardiac death incidence declined by 17% in Olmsted County -- where Mayo Clinic is located -- with the laws, though not statistically significant at P=0.13 with the relatively low number of events, the group reported online in the Archives of Internal Medicine.
Other than the expected decline in smoking prevalence from making it less convenient, cardiovascular risk factors remained largely stable in the population there, supporting an effect of the bans themselves, they pointed out.
"Exposure to second-hand smoke should be considered a modifiable risk factor for MI," they wrote. "All people should avoid second-hand smoke exposure as much as possible, and those with coronary heart disease should have no exposure to second-hand smoke."
These additional data supporting smoke-free policies should encourage more locales to adopt them, Hurt and colleagues added.
"Second-hand smoke does matter, and the results of this study will help us to be able to move forward with policies and guidelines to be able to minimize second-hand smoke," Lauren Whitt, PhD, of the University of Alabama at Birmingham, agreed in an interview with MedPage Today.
Other studies of smoke-free workplace and public place laws have pointed to declines in acute MI rates and hospitalizations, fewer asthma admissions among children, and improved quality of life, Sara Kalkhoran, MD, and Pamela M. Ling, MD, MPH, both of the University of California San Francisco, pointed out in an invited commentary.
"Moving forward, we should prioritize the enforcement of smoke-free policies, eliminating loopholes in existing policies as well as encouraging expansion of smoke-free policies to include multi-unit housing, motor vehicles, casinos, and outdoor locations," they wrote.
"Clean air laws encompassing larger portions of the population will help to establish a cleaner bill of health for all."
Olmsted County enacted a smoke-free restaurant law in 2002 and extended the ban to include all workplaces, including bars, in 2007.
Hurt's group compared outcomes through records of the Mayo Clinic and the one other medical center serving the county in the Rochester Epidemiology Project.
The incidence of MI fell from 151 per 100,000 population in the 18-month period before either ordinance to 101 per 100,000 in the 18 months after both were into effect (P<0.001).
Incidence of sudden cardiac death went from 109 to 92 per 100,000 population over the same period (P=0.13).
The researchers cited CDC data for Minnesota from the Behavioral Risk Factor Surveillance System showing a decline in smoking prevalence among adults from 20% in 2000 to 15% in 2010.
However, no other risk factors moved in a direction expected to reduce MI rates. Diabetes and obesity rose, while hypertension and high cholesterol prevalence stayed relatively flat.
"As trends in other risk factors do not appear explanatory, smoke-free workplace laws seem to be ecologically related to these favorable trends," Hurt's group wrote.
They noted, though, that these trends occurred against a backdrop of declining incidence of sudden cardiac death over the past 30 years and other tobacco control efforts in the state.
Other limitations included lack of data on self-reported or biochemical markers of second-hand smoke exposure, and the primarily white population studied.
The study was supported in part by grants from ClearWay Minnesota; the National Heart, Lung, and Blood Institute; and the National Institute on Aging.
The researchers reported having no conflicts of interest to disclose.
Kalkhoran and Ling reported having no conflicts of interest to disclose.
From the American Heart Association: