Heart disease trends: Prevalence in women nearly equal to men

February 1, 2010

Middle-aged women are gaining ground on their male counterparts in their prevalence of myocardial infarction and their cardiovascular risk factor scores, according to a review of the National Health and Nutrition Examination Surveys over time.

Middle-aged women are gaining ground on their male counterparts in their prevalence of myocardial infarction (MI) and their cardiovascular risk factor scores, according to a review of the National Health and Nutrition Examination Surveys (NHANES) over time.1

The data point to a cardiovascular risk burden that is worsening among women in relation to men, said the study's principal investigator, Amytis Towfighi, MD.

Heart disease patterns in women resemble those of men in other ways. Another study shows that the gap between younger men and younger women in hospital mortality after acute MI is shrinking,2 and a Canadian researcher recently presented data to show that women with MI experience the same symptoms (ie, chest pain and discomfort) as do men.3

More MI; risk factors not improving

Towfighi and colleagues used the 2 phases of NHANES to examine changes in the sex-specific prevalence of MI (determined by a self-reported physician diagnosis of heart attack) and the Framingham coronary risk score (FCRS) among US adults 35 to 54 years old.1 The first phase of NHANES was conducted from 1988 to 1994, and the second phase, from 1999 to 2004.

The prevalence of MI decreased among men, from 2.5% during the first phase of NHANES to 2.2% during the second phase, but increased from 0.7% to 1.0% among women.

Among those without a history of MI, the mean FCRS declined in men between the first and second surveys (8.6% vs 8.1%; P=.07) but remained stable in women (3.0% vs 3.3%; P=.02).

"In the past we thought that this age group of women was protected against heart disease," said Towfighi. "Although their rates are still lower than men's, they are going up, so they're not absolutely protected."

In looking at the individual components that make up the FRCS, fewer improvements were observed in women than in men.

Only levels of high-density lipoprotein (HDL) cholesterol improved in women. Total cholesterol levels, systolic blood pressure (SBP), and the prevalence of smoking remained stable, but the presence of diabetes mellitus and obesity got worse, Towfighi said. In contrast, men showed improvements in HDL cholesterol, SBP, and history of smoking. As in women, the men showed higher rates of diabetes and obesity from the first survey to the second.

"We've known that women's risk factors were not as well-controlled as men's," Towfighi noted. "The take home is that we have to be more aggressive in identifying and treating cardiovascular risk factors in women."

Obesity as a driver

One reason that lipid levels are staying stable despite the increased prevalence in obesity is that medication use, particularly statins, is increasing, Towfighi believes. "However, markers of diabetes went up in this study, suggesting that the metabolic syndrome is probably taking effect here but is being masked by medications," she said.

When it comes to the health of middle-aged women, Towfighi believes that health systems may overlook cardiovascular risk factors in favor of risk factors for other diseases that strike women disproportionately.

An opposite trend in hospital mortality for MI

In seemingly better news for women, the difference in hospital mortality after acute MI between younger men and younger women is narrowing.2 Temporal changes in risk profiles appear to explain much of this shrinking of the mortality difference, found Viola Vaccarino, MD, PhD.

Vaccarino and colleagues examined case-fatality rates of MI over 4 periods (1994-1997, 1998-1999, 2000-2003, and 2004-2006) using the National Registry of Myocardial Infarction, a prospectively collected nationwide database of patients admitted with acute MI at approximately 1,600 hospitals.

In-hospital mortality rates declined over time in both genders in all age groups. The decline was largest in the women younger than 55 years (a decline of 52.9%) and smallest in men younger than 55 years (a decline of 33.3%). The absolute decrease in hospital mortality was 3 times greater in the women in the youngest age group relative to their male counterparts (absolute reductions of 2.7% and 0.9%, respectively).

Women were less likely than men to undergo coronary catheterization and revascularization procedures at all time points in the study, so in-hospital treatment could not account for the narrowing in mortality between younger women and younger men, said Vaccarino.

Vaccarino cautioned that although the gap in hospital mortality between the 2 sexes is narrowing in patients younger than 55 years, "there is still a difference between women and men and it's still significant, so more needs to be done to address this gap," she said.

Early recognition of risk factors

"We need to make sure that people at high risk are recognized early enough so that intervention can be started," said Vaccarino. "We need to focus on many behavioral risk factors that are among the strongest risk factors for heart disease: a healthy diet, physical activity, medication adherence, and avoiding smoking."

Consistent with this message is the discovery that the transition to menopause is accompanied by unfavorable changes in lipid profiles, according to recent findings from the Study of Women's Health Across the Nation (SWAN).4

It is before this transition occurs that physicians should be especially vigilant in counseling women about lifestyle measures that have a positive influence on their cardiovascular risk, believes the study's lead investigator, Karen A Matthews, PhD.

SWAN is a prospective longitudinal study of 3,302 white and minority women who were premenopausal or early perimenopausal at baseline. A total of 1,054 of the women who had had their final menstrual period and were not using exogenous hormone therapy by the end of 9 years of follow-up were included in a study to assess patterns of coronary heart disease (CHD) factors over time.

The CHD risk factors assessed were levels of lipids and lipoproteins, glucose, insulin, blood pressure, fibrinogen, and C-reactive protein. Of these, only total cholesterol, low-density lipoprotein cholesterol, and apolipoprotein B had worsened significantly around the time of the final menstrual period, reported Matthews. The pattern was consistent across all ethnic groups comprising the study population.

"These findings are consistent with the hypothesis that the increase in CHD in postmenopausal women may in part be related to the earlier changes in lipids associated with the menopausal transition," wrote Matthews. "This study underscores the need to closely monitor lipid profiles of premenopausal and perimenopausal women and the importance of emphasizing proven lifestyle measures and therapeutic interventions before the menopause transition to counter and possibly prevent this adverse change in lipids associated with menopause itself."

MI symptoms are similar between women and men

Contrary to the belief that women tend to experience atypical symptoms of MI, women were as likely as men to have chest pain as a sign of MI, according to lead author Martha H Mackay, RN, who presented her data at the Canadian Cardiovascular Congress 2009.3

Methodologic issues have plagued past attempts to characterize the symptoms of acute coronary syndromes (ACS) in women, Mackay said. In her study, 305 patients (39.7% of whom were women) who were undergoing nonemergent percutaneous coronary intervention (PCI) were asked about their sensations during balloon inflation (mean age, 63.9 years). A total of 245 of the patients had electrocardiographic-evident ischemia during angioplasty balloon inflation.

No gender differences were found in the rates of chest discomfort and other typical ACS symptoms, said Mackay. Women were more likely to report throat, jaw, and neck discomfort, as well as only nonchest discomfort. Older patients were more likely to report chest or throat discomfort; prior PCI increased the likelihood of reporting jaw discomfort; and prior MI increased the chance of reporting neck discomfort.

According to Mackay, "In light of these findings, it is important that clear educational messages be crafted to ensure both women and health professionals realize classic symptoms of ACS are equally common in women and men."

REFERENCES

1. Towfighi A, Zheng L, Ovbiagele B. Sex-specific trends in midlife coronary heart disease risk and prevalence. Arch Intern Med. 2009;169(19):1762-1766.

2. Vaccarino V, Parsons L, Peterson ED, Rogers WJ, Kiefe CI, Canto J. Sex differences in mortality after myocardial infarction: changes from 1994 to 2006. Arch Intern Med. 2009;169(19):1767-1774.

3. Mackay MH, Ratner PA, Buller CE, Johnson JL, Humphries KH. Gender differences in reported symptoms of acute coronary syndromes. Can J Cardiol. 2009;25(suppl B):115b.

4. Matthews KA, Crawford SL, Chae CU, et al. Are changes in cardiovascular disease risk factors in midlife women due to chronological aging or to the menopausal transition? J Am Coll Cardiol. 2009;54(25):2366-2373.