Myocardial Infarction and Oral Contraceptives
The association between myocardial infarction and the use of oral contraceptives appears to be a real one, even increasing in second-generation drugs, said authors from the Netherlands in an article in the December 20, 2001, issue of The New England Journal of Medicine (N Engl J Med. 2001;345:1787–1793). The risk appears to decrease, however, in third-generation birth control pills, according to Bea C. Tanis, MD, and co-authors from the Leiden University Medical Center in Leiden and the University Medical Center in Utrecht.
In their population-based, case-control study, the authors enrolled 248 women ages 18 through 49 years of age who had had a first myocardial infarction between the years 1990 and 1995, as well as 925 control women. Subjects were matched for age, calendar year of the index event, and area of residence. The women supplied information about their use of oral contraceptives and major cardiovascular risk factors. The authors also analyzed the women’s DNA for the presence of factor V Leiden and the G20210A mutation in the prothrombin gene.
They found that that odds ratio of myocardial infarction among the women who used any type of combined oral contraceptive when compared with those who did not use oral contraceptives was 2.0. The adjusted odds ratio was 2.5 among women who used second-generation oral contraceptives, but only 1.3 among those who used third-generation pills. The odds ratio was 2.1 for those who lacked a prothrombotic mutation and 1.9 for those with a mutation.
The authors concluded that the risk of myocardial infarction increased with the use of oral contraceptives, particularly second-generation pills. They wrote, however, that the results with regard to third-generation oral contraceptives were inconclusive, but that they suggested a lower risk when compared with second-generation drugs. Prothrombotic mutations did not appear to affect the risk of myocardial infarction significantly in women who used the contraceptive pills.
“The use of third-generation oral contraceptives did not increase the risk significantly (odds ratio, 1.3). The direct comparison of second- and third-generation oral contraceptives suggested that the use of third-generation agents was associated with a lower risk of myocardial infarction, but the confidence interval was wide and therefore a definite conclusion could not be reached,” the authors wrote. “Although the risk of myocardial infarction in users of oral contraceptives is small in absolute terms, it has an important effect on women’s health, since 35 to 45 percent of women of reproductive age use oral contraceptives. Because all combined oral contraceptives are equally effective means of birth control, the issue of safety is paramount. Since the absolute risk of myocardial infarction is highly age-dependent, the risk associated with the use of oral contraceptives will have the greatest effect in older women. A large number of women who were 35 years of age or older still used oral contraceptives (26 percent). This finding, however, may be specific to the Netherlands (the rate is 24 percent in national statistics). Before prescribing oral contraceptives, clinicians should screen women for conventional risk factors for cardiovascular events, and they should remember that the most important advice they can give these women remains to quit smoking.”
Stress Tests May Predict Restenosis in Stent Patients
Administering a nuclear cardiac stress test shortly after a coronary angioplasty with stent implantation may predict restenosis (recurrent narrowing of the arteries), wrote Spanish authors in the December issue of The Journal of Nuclear Medicine (J Nucl Med. 2001;42:1768–1772). The authors, led by Josep Rodes-Caubau, MD, of the Hospital General Universitari Vall d’Hebron in Barcelona, Spain, identified 30 patients who had undergone stent implantation and received a cardiac stress test within a week of the procedure. The authors found that 17% of the patients (5 of 30) who had the stent implantation still had myocardial ischemia (lack of blood and oxygen to the heart) early after the procedure, as assessed by cardiac stress testing.
A total of 23 patients underwent follow-up angiography to determine if there was restenosis, and of those patients, 26% had restenosis. Of those who had early, identified problems, 75% experienced restenosis of the stented area versus only 16% of those whose studies had not shown any defects. Four patients (13%) underwent target lesion revascularization to clear up recurrent blockages. Half of these restenotic events took place in patients with residual ischemia after stent implantation.