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It is highly desirable to get coronary artery disease (CAD) patients off of cigarettes, and nicotine patches have been effective for smoking cessation. Thus, the safety of nicotine patches in patients with myocardial ischemia due to CAD is of interest. Mahmarian et al studied 36 patients who smoked one pack of cigarettes per day, had known CAD, and had reversible ischemia on exercise SPECT thallium. The patients were started on the 14 mg nicotine patch, and, after three days, SPECT was repeated. Then, they were advanced to the 21 mg patch and SPECT repeated. The nicotine patch resulted in a significant reduction in total perfusion defect size from 18% smoking to 13% on 14 mg and 12% on 21 mg (P < 0.001). This reduction was accompanied by an increase in exercise duration from 452 sec to 472 sec and 493 sec on the 14 and 21 mg doses (P < 0.001), respectively. Interestingly, reduced defect size correlated with reduced carbon monoxide levels (R = 0.87) that decreased from 23 ppm to 13 ppm (P < 0.001) due to a 74% reduction in smoking. Mahmarian et al conclude that nicotine patches used to reduce cigarette smoking decrease exercise-induced myocardial ischemia.
Since nicotine activates the sympathetic nervous system, there has been concern that ischemic events may be precipitated by the patches, especially if the patients continue to smoke. This study seems to put these concerns to rest and suggests that carbon monoxide and possibly other components of smoke are more likely to cause ischemia than nicotine. In fact, Mahmarian et al point out that the magnitude of the reduction in perfusion defect area on the patch with reduced smoking is similar to the magnitude of reduction they have observed with anti-ischemic drug therapy. Another piece of evidence that smoking cessation is the safest and least costly approach to the treatment of chronic ischemic heart disease.
One caveat is that this is a small study and did not have the power to assess cardiac events such as death and myocardial infarction. It is well known that neither the presence nor the severity of ischemia is highly predictive of subsequent coronary events, even though there is a general relation. Thus, it is possible that despite reduced ischemia, the higher nicotine levels on the patch might contribute to an event, especially if the patient keeps smoking. However, if this short-term risk exposure results in smoking cessation, the long-term benefits should dominate. (Dr. Crawford is Chief, Division of Cardiology, University of New Mexico, Albuquerque.)