And many of these smokers do not see it coming. Smokers who die of heart attacks and strokes are much more likely than nonsmokers to be unaware that they have cardiovascular disease, particularly when they’re young. Among young adults in their twenties and thirties, smokers are at least twice as likely as nonsmokers to die of a heart attack or stroke without a prior cardiovascular disease diagnosis, the study found. Middle-aged adults in their forties and fifties have a roughly 80 percent higher risk of these sudden deaths, and the risk remains at least 30 percent higher for older adults. “The risk for heart disease is sometimes thought of as something that doesn’t affect younger adults and is a long time away,” says the lead study author, Sadiya Khan, MD, an assistant professor and a cardiologist at the Northwestern University Feinberg School of Medicine in Chicago. “These results emphasize that even short-term exposure to smoking can have negative consequences,” Dr. Khan says. The overall risk that death will be the first sign of cardiovascular disease is relatively low. In women, this happens to 1.6 percent of young adult smokers, 4.5 percent of smokers in their forties and fifties, and 4.9 percent of older adults who smoke. Among men, this occurs with 1.7 percent of young adults who smoke, as well as 4.8 percent of middle-aged smokers and 6.7 percent of elderly smokers. But more than 34 million U.S. adults smoke cigarettes, and each year more than 480,000 of them die as a result, according to the American Heart Association. For the new study, researchers examined data on more than 106,000 U.S. adults who were part of nine previously published studies examining how smoking and other lifestyle factors impact cardiovascular health. None of these adults had cardiovascular disease at the start of the studies, which followed participants for 10 to 25 years to see how many of them developed heart disease or experienced events like heart attacks or strokes. One limitation of the new study is that smoking was only assessed at a single point in time in the nine studies that were included in the analysis, and it’s possible some people quit or took up smoking later in life. Another drawback is that researchers lacked data on how many years people smoked or the number of cigarettes they smoked each day, both of which can influence the risk of events like heart attacks and strokes. RELATED: Frequent Marijuana Use Increases Risk of Stroke and Heart Arrhythmias in Young Adults Much of the earlier research on smoking and the risk of cardiovascular disease has focused on older adults. One study published 15 years ago in Circulation, for example, followed 50-year-olds without cardiovascular disease to see what factors might increase their risk of developing or dying of heart attacks and strokes. Smokers had almost twice the risk of heart events, as well as a shorter life span. Another older study, published in the New England Journal of Medicine, focused on the lifetime risk of cardiovascular disease events in adults 45 years and older based on smoking status and other major risk factors such as diabetes, high blood pressure, and elevated cholesterol levels. With just one of these risk factors, the lifetime chance of a heart attack was 37.5 percent for men and 18.3 percent for women. And the lifetime odds of a stroke were 8.3 percent for men and 10.7 percent for women. All these odds were far higher for smokers than for people who were nonsmokers and had none of the other major risk factors for cardiovascular disease. Smokers may not understand their elevated risk of cardiovascular disease partly because there are so many other factors — including diabetes, obesity, high blood pressure, and high cholesterol — that can also contribute to the risk of heart attacks and strokes, says Judith Prochaska, PhD, MPH, a professor of medicine and a tobacco researcher at Stanford University in California.
Not a ‘Smoking Disease’
Smokers can more easily grasp the risk of lung cancer because the connection is so much more clear-cut than it is for heart disease, Dr. Prochaska says. “Smoking is by far the leading cause of lung cancer — if not for cigarette smoking, lung cancer would be a rare disease. Whereas, with heart disease, there are many causes, and only about one in five cases of heart disease is attributed to cigarette smoking.” This means that even though heart disease is the leading cause of death among smokers, it doesn’t get recognized as a “smoking disease” the way lung cancer does, Prochaska says. The effects of smoking can also take time to accumulate, says James Davis, MD, an associate professor at Duke University School of Medicine in Durham, North Carolina, and the director of the Duke Smoking Cessation Program.
Risk of ‘Plaque Instability’
Smoking does two things that lead to cardiovascular disease, Dr. Davis says. First, smoking increases the development of plaque — deposits of fatty substances and other debris inside arteries. Second, smoking makes plaque more likely to form clots that can block arteries and cause heart attacks or strokes, a process known as plaque instability. “A key finding in this study is that at a population level, we see that smoking is associated with an increase in heart attack as the initial symptom of coronary disease,” Davis says. “This is consistent with smoking leading to plaque instability.” The study results also suggest that it may not take decades of smoking for plaque instability to develop, Davis says. Instead, this can happen in younger adults, contributing to the increased risk that a heart attack or stroke might be their first indication that they have cardiovascular disease. The good news, however, is that plaque accumulation and instability can be reversed when people quit smoking, Davis says. “After 10 to 15 years of not smoking, a person’s heart disease risk returns to looking like that of a nonsmoker.”
