The onset of occurrence of heart disease in women is usually significantly later than in men due to the vascular protective effect of estrogen which helps to delay the formation of atheroslerosis.
In fact, however, coronary artery disease has come to be recognized as an increasingly important killer of woman both peri and postmenopausally, but also premenopausally, although the data is more difficult to obtain due to the overall low incidence of disease in this population. The data on frequency of coronary disease in younger woman is in general extremely limited.
In the Framingham Heart Study. (Kannel WB, Abbot, RD, Incidence and prognosis of unrecognized myocardial infarction. An update on the Framingham Study. N Engl J Med 1984: 311:1144.) the incidence of myocardial infarction (MI) over a 10 year follow up in women 35 to 44 years old was 5.2/1000. It was 8-9 times greater in women in the 55 to 64 year old age group.
In a prospective study of >7000 women of mean age 27 years at baseline, followed for an average of 31 years, there were 47 deaths related to coronary artery disease. Coronary-related mortality rates for those women with no risk factors, a single risk factor, or two or more cardiac risk factors were 0.7, 2.4, and 5.4 per 1000 patient-years, respectively (Daviglus ML, Stamler J, Pirzada A, et al.
Favorable cardiovascular risk profile in young women and long term risk of cardiovascular and all-cause mortality. JAMA 2004: 292:1588.) Cigarette smoking was by far and away the most common risk factor in these young patients. Younger patients with coronary disease also more often have a family history of premature disease. Interestingly, type 2 diabetes mellitus and hypertension appear to be less common in young patients with premature disease than in older female patients, although they may exhibit subtle problems with impaired glucose metabolism.
An excellent study was published from Nantung University in China (Lu Yihua, MM, Jiang Yun, MD and Zhao Dongshen, MD. Coronary Artery Disease in Premenopausal and Postmenopausal Women. Int Heart J2017;58: 174-179.) A total of 57 premenopausal and 178 postmenopausal cases were enrolled according to their status at the time of diagnosis.
It is important to recognize that symptoms among younger women may be quite atypical and that patients with silent myocardial ischemia frequently have more extensive and severe disease. This data correlates with earlier studies that younger women with coronary artery disease may not necessarily manifest chest pain. This study demonstrated the fact that a large preponderance of young women (82.46%) presented with acute coronary syndrome (ACS), as opposed to a minority of postmenopausal women (48.88%).
Premenopausal women tended to present without pain but progress rapidly to myocardial infarction. Autopsy studies in young women have demonstrated that their coronary artery lesions contain relatively less calcium and dense fibrous tissue than those of older women and of men. Rather they are comprised mainly of fatty plaque deposits which may be easily ruptured and cause a biologically unstable situation. Coronary angiography of the young women in this study also demonstrated a common pattern of single vessel disease usually limited to the left anterior descending artery. This pattern has been seen repeatedly in other such studies of young people in general, both male and female.
Finally, cardiovascular risk factors were highly valuable predictors of the presence and severity of coronary disease. The prevalence of hypertension, type 2 diabetes and hyperlipidemia were significantly lower in the premenopausal group of women. Smoking was again reported as the most prevalent risk factor in younger women, causing endothelial dysfunction, spontaneous platelet aggregation, coronary spasm and adverse hemostatic effects.
There was again a strong suggestion that females with a positive family history of premature coronary artery disease should have heightened concern about the occurrence of such disease prior to menopause. In any event, bottom line is that the comparison results suggested that traditional risk factors in premenopausal women did not appear to be as strongly linked with the presence of coronary disease.
Spontaneous coronary artery dissection is a very rare cause of acute myocardial infarction that is far more common in younger patients below the age of 50 and in women. In woman in particular the risk of spontaneous dissection is increased during the peripartum period.
Lastly, a variety of other possible contributing factors have been identified in young patients with unstable coronary artery disease and myocardial infarction. These factors include oral contraception use in premenopausal women, especially when combined with significant use of tobacco.
Frequent use of cocaine has been identified as accounting for 25% of nonfatal infarctions (Qureshi Al,Suri MF, GutermanLR, Hopkins LN. Cocaine use and the likelihood of nonfatal myocardial infarction and stroke: data from the Third National Health and Nutrition Examination Survey. Circulation 2001:103:502.) Finally, in women, acute myocardial infarction may be more common during the follicular phase of the menstrual cycle, during a period of relative hypoestrogenemia.