Cardiovascular risk in women
Cardiovascular disease kills women at a high rate, and women who have it differ from men in how the disease presents, how it is managed, how it responds to treatment and in its adverse outcomes. The American Heart Association's 2007 guidelines for preventing it in women grade a woman's risk in three classes and set lifestyle, risk-factor and preventive drug interventions.
Mortality
As of 2007, almost every minute a woman dies of some form of cardiovascular disease. The mortality rate for women declined every year from 2000 to 2004, but it remained higher than the rate for men. Nanette Wenger attributed the decline to improvements in the management of heart disease and not to prevention, and concluded that a great opportunity remained to drive mortality down further through prevention.
Differences between women and men
Studies of stable angina pectoris, acute coronary syndrome and myocardial infarction have found differences between men and women in the clinical presentation, the approach to management, the response to treatment and the adverse outcomes. A recurring theme is what women with cardiovascular disease are like at presentation: they tend to be older and are more likely to have comorbidities such as hypertension, diabetes and heart failure. As a result, women have more complications, and yet they are less likely than men to be treated appropriately. Women younger than 50 years have twice the risk of dying from a myocardial infarction that men of the same age have.
Assessing a woman's risk
Because heart disease develops in women ten years later than in men, lifetime risk is more important than the ten-year risk used to determine the Framingham risk score. The 2007 AHA guidelines introduced a simpler classification, which grades a woman as high risk, at risk or at optimal risk.
High risk covers established heart disease, cerebrovascular disease, peripheral artery disease, abdominal aortic aneurysm, end-stage or chronic renal disease, and diabetes mellitus. At risk covers a ten-year Framingham global risk above 20%; more than one major risk factor for cardiovascular disease, such as smoking, poor diet, inactivity, obesity, family history, hypertension or dyslipidaemia; evidence of subclinical vascular disease; metabolic syndrome; and poor exercise capacity or an abnormal heart rate after stopping exercise. Optimal risk is a Framingham global risk below 10% together with a healthy lifestyle and no risk factors.
A physical examination should include an evaluation of cardiovascular risk. When Wenger asked an audience how many of them had had their waist circumference measured by their physician, no one raised a hand except Wenger herself.
Preventive interventions
The preventive interventions the 2007 AHA guidelines address fall into three groups: lifestyle interventions, major risk-factor interventions and preventive drug interventions.
Preventive interventions are of value throughout a woman's life, and a partnership between women and their health care providers is important in reducing cardiovascular risk.
Lifestyle interventions
After a smoker stops, pulmonary function improves by 20% to 30% within two to three months, the risk of heart disease falls by half after one year, and after five to fifteen years the risk of stroke is similar to that of someone who never smoked. Quitting before the age of 50 halves the risk of dying over the next fifteen years.
Women should do moderate-intensity physical activity for a total of 30 minutes daily, and for 60 to 90 minutes if they need to lose weight or to sustain a previous weight loss. When a patient gives excuses for not exercising, Wenger tells her that if she cannot find time for exercise she had better find time for disease.
The heart-healthy diet recommended by the AHA consists of plenty of fruit and vegetables; whole-grain, high-fibre foods; fish twice weekly; saturated fat limited to 7% to 10% of energy; cholesterol below 300 mg per day; alcohol limited to one drink per day; sodium no greater than a teaspoon of salt per day; and trans fat as low as possible.
A healthy weight is a body mass index between 18.5 and 25 kg/m² with a waist circumference under 35 inches. To help patients lose weight, Wenger gives them the 250:250 rule: exercise to burn an extra 250 calories a day and eat 250 fewer calories a day. That comes to 500 fewer calories a day, or 3,500 a week, which is one pound of weight loss a week.
Omega-3 fatty acid supplements may help women with cardiovascular disease, but they are not routinely recommended for healthy women. Depression screening is recommended for women with cardiovascular disease, and cardiac rehabilitation should be prescribed for women who have had a recent event.
Risk-factor targets
The optimal blood-pressure goal for everyone is below 120/80 mm Hg, and it should be maintained through lifestyle interventions. Pharmacotherapy is indicated when the blood pressure is higher than 140/90 mm Hg. For a person with chronic kidney disease or diabetes, pharmacotherapy is initiated at a blood pressure of 130/80 mm Hg or higher.
For lipids and lipoproteins, Wenger recommended memorising three numbers: 100, 50 and 150. Low-density lipoprotein cholesterol (LDL-C) should be below 100 mg/dL and triglycerides below 150 mg/dL. High-density lipoprotein cholesterol should be greater than 50 mg/dL. For a person at very high risk, however, an LDL-C below 70 mg/dL is a reasonable goal.
Diabetes is a coronary heart disease risk equivalent in women: a diabetic woman's risk of coronary heart disease equals that of a non-diabetic person with a prior myocardial infarction. In women with diabetes, lifestyle and pharmacotherapy should be used to control glucose to a haemoglobin A1c below 7%.
Preventive drug interventions
Aspirin is recommended for high-risk women unless it is contraindicated or not tolerated, in which case clopidogrel should be substituted. A beta-blocker and an angiotensin-converting-enzyme inhibitor should be prescribed for all women after a myocardial infarction, and aldosterone blockade should also be considered.
Hormone-replacement therapy, antioxidant supplements and folic acid have been found to be either not useful or ineffective, and potentially harmful, for preventing cardiovascular disease or myocardial infarction in women.