HEALTH MATTERS: Ejection fraction: Numbers we all should knowQ. I recently saw my physician for a complete evaluation, and she told me that I am at low risk for coronary heart disease. What exactly does that mean?
By: Dr. Joshua Wynne, Grand Forks Herald
Q. I recently saw my physician for a complete evaluation, and she told me that I am at low risk for coronary heart disease. What exactly does that mean?
A. We know there are certain risk factors that, when present, predict that the person has underlying blockages in the heart arteries and thus is at some risk of a heart attack. The more risk factors present, the higher the risk. People without any risk factors are at low risk of heart problems, with a 10-year risk of less than 10 percent. Those with one or more risk factors are said to be at intermediate risk, with a 10 to 20 percent chance of heart problems over a decade. Those with multiple risk factors are said to be at high risk, with a 10-year risk of more than 20 percent. Important risk factors for the development of coronary artery disease include elevated cholesterol, elevated blood pressure, diabetes, cigarette smoking, obesity, physical inactivity, advancing age and being male (a post-menopausal woman also is at increased risk). It is important to note that low risk doesn’t mean no risk, and high risk doesn’t mean a guarantee of problems. Nevertheless, this relative-risk grading system is useful, and it suggests that those at higher risk do something (like stop smoking or get their cholesterol under control) to lower their risk of heart problems. Many of the risk factors are potentially modifiable, including obesity, high cholesterol, cigarette smoking, and physical inactivity. Unfortunately, I haven’t figured out an antidote to advancing age.
Q. While I was in the doctor’s exam room, I saw a sign that told me to “know my numbers,” especially my ejection fraction. What is ejection fraction, and why is it important?
A. The health numbers we all should know include our weight, blood pressure, cholesterol, blood sugar level (looking for diabetes), and the ejection fraction for patients with heart disease. The ejection fraction (or EF) is the percentage of blood in the heart that is ejected with each heartbeat; we usually measure it by obtaining an echocardiogram (ultrasound) of the heart. Normally, at least half of the blood in the heart is pumped out with each heartbeat, so the ejection fraction usually is 50 percent or more. The ejection fraction tends to decrease slightly with normal aging, but typically is over 50 percent.
Ejection fractions below 50 percent occur in a wide variety of conditions, including heart attacks and damage from long-standing high blood pressure. As the ejection fraction gets lower, there is a greater risk of symptomatic heart failure manifested by shortness of breath and ankle swelling.
Once the ejection fraction is lower than around 30 percent, there is an increased risk of death because of repetitive but ineffective extra heartbeats. While medicines in general are ineffective in this setting for preventing sudden death, we are able to insert a special type of pacemaker (called an ICD, or implantable cardioverter defibrillator) that can shock the heart back to normal if a serious rhythm irregularity develops. We normally don’t measure the ejection fraction unless heart disease is suspected or documented. And if you do have heart problems, hope that your EF is 50 percent or above; otherwise, additional evaluation and consideration of treatment options is indicated.
Wynne is vice president for health affairs at UND, dean of the School of Medicine and Health Sciences, and a professor of medicine. He is a cardiologist by training.
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