Up to 50% of people who have a first heart attack—which often results in sudden death—don't experience prior chest pain, shortness of breath or other red flags for cardiovascular disease. A heart attack is their first and only symptom.
In the past, cardiologists relied solely on the presence of risk factors—a family history of heart disease, smoking, diabetes, etc.—to identify "silent" heart disease.
New approach: An international task force of leading cardiologists has issued updated guidelines that could prevent more than 90,000 deaths from cardiovascular disease each year in the US. Most of these patients have no prior symptoms.
RISK FACTORS AREN'T ENOUGH
Most heart attacks and many strokes are caused by atherosclerosis, buildup of cholesterol and other substances (plaque) within artery walls.
Over time, increasing accumulations of plaque can compromise circulation—or result in blood clots that block circulation to the heart (heart attack) or brain (stroke).
Plaque can accumulate for decades within artery walls without causing the arterial narrowing that results in angina (chest pain) or other symptoms. Even patients with massive amounts of plaque may be unaware that they have heart disease until they suffer a heart attack or sudden death.
Guidelines created by the Screening for Heart Attack Prevention and Education (SHAPE) Task Force call for noninvasive screening of virtually all asymptomatic men ages 45 to 75 and women ages 55 to 75.* The tests can detect arterial changes that are present in the vast majority of heart attack patients. The SHAPE Task Force identified two tests—a computed tomography (CT) scan of the coronary arteries and an ultrasound of the carotid arteries in the neck—that are more accurate than traditional risk-factor assessments in identifying high-risk patients.
Most patients require only one of these tests. Which test is recommended will depend on insurance coverage and/or other underlying health conditions and risk factors. Although these tests are widely available, health insurers do not always cover the cost, which ranges from about $200 to $400 each.
- Coronary artery screening. Calcium within the coronary arteries always indicates that a patient has atherosclerosis (whether or not blockages are present). Calcium is a marker of actual disease, not just the risk of disease.
What’s involved: The patient is given a CT scan of the heart and three coronary arteries. Undressing isn't required—the test is noninvasive and takes about five to 10 minutes.
Dozens of images are taken during the test and then analyzed with computer software. If calcium is present, it's given a score based on severity. A score of 0 is ideal...less than 100 indicates moderate atherosclerosis...100 to 400 represents a significant problem...and more than 400 is severe.
In patients with a score of 0 (no calcium is present), the risk of having a heart attack or stroke over the next 10 years is 0.1%. Patients with a score of 400 or higher are 20 to 30 times more likely to have a heart attack or stroke than those with a score of 0.
- Carotid ultrasound. This test measures the intima media thickness (the gap between the inside of the blood vessel wall and a layer called the media) of the carotid arteries. It also measures the amount of plaque that may be present.
A thickening of the intima media (the values are adjusted for age and sex) is a predictor of stroke as well as heart attack. The presence of any plaque is a red flag—patients who have plaque in the carotid arteries generally will also show evidence of plaque in the coronary arteries.
*Screening for adults age 75 or older is not recommended because they are considered at high risk for cardiovascular disease based on their age alone.
What's involved: The patient lies on an examination table while a technician moves a transducer (a device that emits and receives ultrasound signals) over the carotid arteries on both sides of the neck. Like the CT scan, the test is noninvasive. It takes about 45 to 90 minutes to complete.
TREATING SILENT HEART DISEASE
With screening tests, doctors can target high-risk patients more precisely—and recommend appropriate treatment. The aggressiveness of treatment should be proportionate to the risk level.
It's possible that drugs to reduce levels of existing plaque will be on the market within the next five years. Until then, patients diagnosed with asymptomatic cardiovascular disease (based on one of the above tests) should...
- Get a stress test. Patients who test positive for calcium or plaque in the coronary or carotid arteries should undergo a cardiac stress test. The test, which uses an electrocardiogram, involves walking on a treadmill or riding a bicycle. The test detects impediments in circulation through the coronary arteries and identifies abnormal heart rhythms (arrhythmias) that can occur during exercise in patients with heart disease. Nuclear stress tests (which involve the use of radioactive dye) or echocardiogram Q, type of ultrasound) stress tests generally are more reliable than simple electrocardiogram tests.
Patients with significant blockages in the coronary arteries may require invasive procedures, such as angioplasty or bypass surgery, to restore normal circulation to the heart.
- Control cholesterol and blood pressure. They're two important risk factors for heart attack and stroke—and both are modifiable with medication and/or lifestyle changes. A patient who tests positive for asymptomatic cardiovascular disease needs to treat these conditions much more aggressively than someone without it. For cardiovascular health, aim for a blood pressure of no more than 110 mmHg to 120 mmHg systolic (top number) and 70 mmHg to 80 mmHg diastolic (bottom number). An ideal LDL "bad" cholesterol level is no more than 70.
Most patients can significantly lower blood pressure and cholesterol with lifestyle changes—exercising for 30 minutes at least three to four times a week...losing weight, if necessary...eating less saturated fat and/or trans fat...and increasing consumption of fruits, vegetables, whole grains and fish.
- Other risk factors to control: Smoking, obesity, diabetes, as well as emotional stress/anger, which may lead to a heart attack or angina. It's important to control all of these risk factors because they can amplify each other—for example, a sedentary lifestyle promotes obesity, which can lead to diabetes—or have a cumulative effect that's much more dangerous than an individual risk factor.
For more on silent heart disease, consult the Society for Heart Attack Prevention and Eradication, a nonprofit group that promotes heart disease education and research, 877-742-7311, www.shapesociety.org.