Heart attacks among cigarette smokers may have less to do with tobacco and more to do with genetics, suggests a new study in the Annals of Noninvasive Electrocardiology. The researchers say that a common defect in a gene controlling cholesterol metabolism boosts smokers' risk of an early heart attack and conversely, that smokers without the defect normally have heart attacks no sooner than their non-smoking peers.
While the link between smoking and heart disease was established decades ago, the reasons for that link were unclear. More recent studies suggest smoking interferes with cholesterol metabolism, lowering smokers' levels of "good cholesterol", which protects against heart-attack risk. An estimated 60 percent of smokers face the added risk of a defective gene that also lowers levels of the protective high-density lipoprotein. Therefore, the combination of smoking plus a defective gene substantially accentuates the risk of heart attacks in these patients.
The researchers found that smokers with the genetic defect had their first heart attack eight to nine years earlier than non-smokers. Smokers with a healthy version of the gene had their first heart attack only three years earlier than non-smokers, a difference the researchers considered non-significant.
"Since the frequency of this 'bad' gene in the general population is about 60 percent, many people who smoke have a high risk of experiencing a heart attack at a young age," said researcher Ilan Goldenberg. "This finding should increase awareness for smoking cessation."
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Source: Annals of Noninvasive Electrocardiology
