Smoking affects your cardiac health both before and after a major event like a heart attack. But how much? And does cutting back instead of quitting have a positive effect as well?
There are definitive answers in a new study from Tel Aviv University, the largest and most comprehensive of its kind.
The research found that quitting smoking after a heart attack has about the same positive effect as other major interventions such as lipid-lowering agents like statins or more invasive procedures. Study results were reported in the Journal of the American College of Cardiology.
"It's really the most broad and eye-opening study of its kind," says Dr. Yariv Gerber of TAU's Sackler School of Medicine. "Smoking really decreases your life expectancy after a heart attack. Those who have never smoked have a 43% lower risk of succumbing after a heart attack, compared to the persistent smoker."
But even those with a history of smoking can see their risk sharply decline once they give up the habit. "We found that people who quit smoking after their first heart attack had a 37% lower risk of dying from another, compared to those who continued to smoke," Dr. Gerber says.
Largest study of its kind
In the study, the researchers looked at data collected by TAU senior cardiologist Prof. Yaacov Drory. The data covered more than 1,500 patients, 65 years old or less, who were discharged from hospitals in 1992 and 1993 in central Israel, all after their first acute myocardial infarction. At the time of their first heart attack, 27% of the men in the study had never smoked, some 20% reported being former smokers, while more than half admitted to being current smokers.
After leaving the hospital, the smokers attempted to quit. Among this group, 35% were able to abstain over the next decade or so. Analyzing data spanning more than 13 years, the researchers concluded that the greatest risk of death occurred in those people who continued to smoke, even when socioeconomic measures (education, employment and income), cardiovascular risk factors (hypertension, obesity and exercise) and medical treatment were taken into consideration.
Those who quit smoking before the first heart attack had a 50% lower mortality rate, while those who quit after their heart attack lowered that rate by a whopping 37% compared with those who continued to smoke.
"Information to live with ― literally"
In their study, researchers also quantified the effects of a reduction, as opposed to complete cessation, in smoking. By cutting their habit by only five cigarettes a day, a smoker might see the likelihood of dying within the next 13 years decrease by 18%. The researchers caution, however, that continuing to smoke still carries the risks of cancer and lung disease, and doctors should urge that their patients quit entirely.
"The burden of heart disease on our healthcare system is enormous. The overall impact of smoking on heart attacks and cardiac mortality is therefore much more significant than its impact on lung cancer," says Dr. Gerber. "The effect of smoking on heart health is actually a much bigger public health threat, and most people are not aware of this.
"The novel aspect in our study is that it is the first to show the benefit of a reduction in smoking," adds Dr. Gerber. "This is information that some smokers could live with ― literally. We would like people to consider cutting down as an initial step before complete cessation, especially those who find it impossible to quit right away."