Death from a heart attack or stroke may be the first cardiovascular disease (CVD) event in some people who smoke cigarettes and CVD is the leading adverse health effect among smokers, according to new research published today in the Journal of the American Heart Association, an open access journal of the American Heart Association.

Decades of research links cigarette smoking to premature death caused by cardiovascular disease and other diseases such as lung cancer.

“There is often more awareness and concern about cancer as a result of smoking than heart disease, so we wanted to better define the risks of smoking related to different types of cardiovascular disease and, most importantly, to cardiovascular death,” said lead study author Sadiya S. Kahn, MD, MSc, an assistant professor of medicine in the division of cardiology at Northwestern University’s Feinberg School of Medicine in Chicago.

“In our analysis, even after adjusting for deaths not related to the heart, such as those due to lung cancer, we found that fatal or non-fatal events related to cardiovascular disease are more likely to occur among people who smoke.”

The researchers pooled data from nine long-term cohort studies in the US to evaluate multiple lifestyle factors as well as cardiovascular and other health outcomes. The analysis included data from 106 165 adults (50.4% women; 16.2% Black adults; 50.1% cigarette smokers) between the ages of 20 and 79, who were free of cardiovascular disease at the start of the studies. The new analysis categorised participants by smoking status (either yes or no, self-reported at study enrollment); age (young: 20 to 39 years of age; middle-aged: 40 to 59; and older: 60 to 79); and sex.

Using the combined data, researchers estimated the number of years lived with and without cardiovascular disease according to smoking status and then examined the association between smoking and cardiovascular events after accounting for death from other diseases such as lung cancer. Adjustments were made for age, race, body mass index (BMI), blood pressure and cholesterol levels. The follow-up time for study participants ranged from 10 to 25 years.

The biggest differences in risks and in deaths between the participants who smoked and those who didn’t smoke occurred during middle age. The analysis found:

Middle-aged women who smoked were nearly twice as likely as non-smoking women to have a fatal CVD event as their first sign of CVD.

Middle-aged men who smoked had a 79% chance of having a fatal CVD event as their first sign of cardiovascular disease – about 1.5 times more likely compared to middle-aged men who did not smoke.

For middle-aged women, the long-term rates of CVD risk were nearly 10% higher in those who smoked compared to those who didn’t (34.7% for smokers; 24.8% for non-smokers).

Middle-aged men who smoked had a more than 10% higher long-term risk for cardiovascular disease then men who didn’t smoke (46% for smokers; 35.8% for men non-smokers).

Smoking was associated with the development of cardiovascular disease at an earlier age, by five years in middle-aged men and nearly four years in middle-aged women. Similar results were seen in younger and older adults, so that a greater number of years lived without CVD was seen across all non-smoking participants in all age and sex groups.

“Our findings note that preventing a heart attack, stroke or heart failure is vital, yet preventing unexpected sudden death as the first manifestation of cardiovascular disease is clearly a priority. People who smoke may not realise the harm cigarettes are causing their body until it’s too late,” Khan said. “Another notable finding among people who smoked was the early onset of CVD, and among those who developed CVD, how much younger they were. There’s not a lot of research on young adults who smoke, particularly among young men. Our study adds important perspective.”

Among young adults, 20 to 39 years of age, the analysis found:

The risk for CVD started to increase significantly in young men who smoked near the 10-year follow-up mark, while in young women the increased risk for CVD in those who smoked became more evident near the 20-year follow-up mark.

With respect to CVD subtypes, young men who smoked had the highest long-term risk for heart attacks (24%), while young women had the highest long-term risk (11.3%) for other CVD causes of death, such as stroke or heart failure.

Among all age groups, a majority of the first CVD events were fatal or nonfatal heart attack. Fatal and nonfatal strokes were the next leading causes of first CVD event among those in the young age group. Heart failure was the second leading cause among the middle-aged and older age groups.

Khan said these results emphasise the contribution of smoking to the earlier onset of CVD overall, and also affected excess CVD risk well into the eighth decade of life in both men and women, even after adjusting for the competing risk of non-CVD death.

Based on these results, the researchers suggest that all people who smoke should talk with their physicians or other healthcare professionals about taking steps toward quitting and improving their cardiovascular health.

“Smoking cessation is very challenging and reaching out to your doctor or other health care professionals for support and resources is important – the sooner the better,” Khan said. “This earlier onset of heart disease and stroke is very crucial to think about with aging and the already known complications of aging.”

There were a few limitations to the study. Smoking status was based on the participants’ report at the beginning of the study, so some could have stopped or started smoking during the follow-up, which would not have been included. Khan also noted that they were not able to account for more specifics about the people who smoked, such as the number of years participants smoked, the number of cigarettes smoked per day or whether people who had previously smoked were included in the studies.