Almost everyone has heard a story about someone who, between the ages of 20 and 30, suffered a heart attack "out of the blue." People will comment, "I can't understand it; he did everything right - ate well, exercised almost every day, and had annual physical exams." In some cases, you might even hear people comment, "He never even had high blood pressure or high cholesterol levels. He was as fit as a fiddle!"
Everyone is left wondering, how can such a thing happen? How does something like this slip under the radar of health care professionals? Frighteningly, statistics show that this type of event isn't all that rare - an estimated 50% of heart attack patients have normal levels of LDL-cholesterol at the time of their heart event.
Enter a risk factor called Lipoprotein(a), or Lp(a), as it is known. This is a type of lipoprotein (cholesterol) that has been confirmed as a risk factor for coronary heart disease, atherosclerosis, thrombosis and stroke. As high levels of Lp(a) travel through the bloodstream, it collects in a person's arteries, leading to gradual narrowing of the artery that can limit blood supply to the heart, brain, kidneys and legs. It can increase the risk of blood clots, heart attack or stroke.
Who's at Risk?
The problem is, Lp(a) levels can be measured by a simple blood test, but it is not included in most standard lipid panel tests. Rather, detection requires an advanced lipid test, which most doctors do not routinely perform. Lp(a) levels that are lower than 50 mg/dL (or 125 nmol/L) are considered normal. Levels higher than this are associated with an increased risk of heart attack, stroke, or narrowed arteries that supply blood to vital organs, often at an early age (younger than 55 in men and 65 in women).
Shockingly, one in five people globally, and an estimated 63 million people in the U.S., have high Lp(a) levels, and most do not know they are at risk. These folks have a 2-4 times higher risk of early heart and blood vessel disease, as compared to people with normal Lp(a) levels.
Predisposition to having high levels of Lp(a) is an inherited condition, present at birth. It is currently the strongest, single inherited risk factor for early coronary artery disease and aortic stenosis (narrowing of the aorta).
So why aren't cardiologists and primary care providers routinely screening for Lp(a)? Gina St. Jean, RN, MSN, CCRN-CSC, a clinical nurse educator for the heart and vascular critical care (HVCC) unit and progressive care unit (PCU) at the Davis Family Heart and Vascular Center at Baystate Medical Center in Springfield, MA, offered an answer - but it's a depressing one. "The cardiologists in my facility are all aware of Lp(a), but they don't screen for it because there's not a clear way to treat it. So, if you find it on a screening test, what does this knowledge bring you? There's very little that can be done about it."
Sadly, although diet and exercise can help reduce the general risk of cardiovascular disease, lifestyle changes have little or no impact on levels of Lp(a). According to research reported on the Lipoprotein(a) Foundation's web site, standard dietary intervention (such as the low-fat diet recommended for weight loss and control of other blood lipids) has little effect on serum Lp(a) level. At present, serum Lp(a) concentration does not appear to be significantly altered by realistic dietary changes and moderate physical activity (as generally recommended for good health).
Other studies, involving treatments such as low-dose aspirin therapies, the use of niacin (vitamin B3) and the effects of fish oil (or, more specifically, a diet rich in n-3 polyunsaturated fatty acids), have been conducted to see if any of these interventions make a real difference in a person's Lp(a) levels, but no dramatic results were discovered. Since 2010, the German healthcare ministry has approved lipoprotein apheresis therapy for patients with elevated lipoprotein(a) levels, as it was determined to effectively lower the incidence rate of cardiovascular events -so this might be one option patients could pursue.
SEE ALSO: Heart Health Month
The bottom line? "More research is needed on how to lower people's Lp(a) levels," St. Jean commented.
The results of one promising study were reported this past summer in the article "Antisense therapy targeting apolipoprotein(a): a randomized, double-blind, placebo-controlled phase 1 study," published in The Lancet. If follow-up research can prove this new drug specifically and effectively lowers elevated Lp(a) levels, then the availability of just one therapeutic agent that works could lead to more widespread testing for elevated Lp(a).
So, even though there aren't many treatment options available today, you might want to ask your doctor to test you for high Lp(a) levels if you have the following risk factors:
• family history of early cardiovascular disease, often at a young age, including heart attack, stroke, circulation trouble in the legs, or narrowing of the aorta;
• heart attack or stroke with no other known risk factors (such as smoking, high LDL cholesterol, diabetes, or obesity);
• high LDL-cholesterol levels, even following treatment with statins or other LDL-lowering medications; and/or
• if you are of African-American and South Asian descent (these two ethnic groups have a higher-than-average incidence).
Remember, since high levels of Lp(a) are a genetic condition, when one member of the family is diagnosed as having high levels, other family members (including parents, siblings and offspring) should be screened also.
While it's true that there isn't much that can currently be done to alter the amount of Lp(a) in your blood, to be forewarned is to be forearmed. If you know you are at risk, you can make it a point to keep abreast of new research and treatment options. For more information, visit the Lipoprotein(a) Foundation's web site at: http://www.lipoproteinafoundation.org/.
Anne Collins is on staff at ADVANCE. Contact her at: www.advanceweb.com.