Higher-tar cigarettes may carry greater heart attack risk

About the study

This study is based on information collected during a study of the risk of first nonfatal heart attack among smokers using nicotine patches. In this prior study, researchers at the University of Pennsylvania enrolled 653 smokers who were hospitalized for their first heart attack (cases) between September 1995 and December 31, 1997, and 2990 non-hospitalized smokers who had never had a heart attack (controls). All participants were aged 30 to 65 and lived in eight counties of eastern Pennsylvania. Cases were identified from acute care hospitals and controls were identified via telephone through a random digit dialing process.

For this recent study of tar yield and heart attack, the researchers studied 587 of the cases and 2685 controls that smoked cigarettes with known tar yields. People were excluded from the study if their heart attack was not their first or was a complication of hospitalization for another condition. Other reasons for exclusion included pregnancy, breast-feeding, not having a telephone, not speaking English, and smoking cigarettes of unknown tar yield.

Both cases and controls were interviewed via telephone. They answered questions about most recent brand of cigarette smoked, duration and frequency of smoking, prior attempts to quit smoking, and other risk factors for heart attack, such as age, sex, race, high blood pressure, diabetes, etc.

Cigarettes brands were classified according to the amount of tar per cigarette:

• Low-tar = 6 mg or less
• Medium-tar = 7 to 12 mg
• High-tar = more than 12 mg

The researchers compared the tar yield of cigarettes smoked by cases (heart attack patients) with the tar yield of cigarettes smoked by controls (smokers who did not have a heart attack).

The findings

Overall, higher-tar cigarettes were associated with a higher risk of heart attack than lower-tar cigarettes. Compared with low-tar cigarettes, medium-tar cigarettes increased the risk of heart attack by 86% and high-tar cigarettes increased the risk by 121%. These statistics were calculated after factoring in all other risk factors for heart attack.

There are limitations to this study, however. First, this study was limited to nonfatal heart attacks in people aged 30 to 65, so these findings may not apply to the risk of fatal heart attack or to people older than 65. Second, the calculations were based on the proposed tar yield of the cigarettes. However, variation in individual smoking behavior, such as how deeply a smoker inhales, can alter the actual dose of tar delivered to the smoker. Third, the calculations were based on the most recent brand of cigarettes smoked, so lifetime exposure to various tar levels from other brands is not known. Finally, people who smoke low-tar cigarettes may be more concerned about their health and therefore more likely to practice other heart healthy habits, such as exercising regularly and eating a healthful diet.

How does this affect you?

Will switching to low-tar cigarettes reduce your risk of a heart attack? Possibly, but you'll still be at higher risk of heart attack than if you didn't smoke at all. While this study suggests that low-tar cigarettes may carry a lower risk of heart attack than higher-tar cigarettes, low-tar cigarettes still increase your risk of heart attack. In addition, previous studies of tar yield and heart attack have produced conflicting results.

To reduce your risk of heart attack, you'll need to quit smoking entirely. Compared with nonsmokers, smokers are 2 to 4 times more likely to have a heart attack, not to mention that smoking increases your risk of stroke and cancers of the lung, larynx, oral cavity, pharynx, esophagus, bladder, pancreas, uterine cervix, kidney, stomach, and some leukemias.

For help quitting smoking, see the American Lung Association website .