Search for Cardiac Biomarkers Not a Simple Answer
What’s really at the root of cardiovascular disease? It’s a question many great minds continue to ponder. In spite of tremendous amounts of research, little new information has emerged to clarify why some people are especially vulnerable, while others are inexplicably robust. Cholesterol levels, C-reactive protein and other biomarkers haven’t helped pinpoint the actual cause or even added much to the early detection tool kit. As our national debate rages about health care, it seems evident that the billions being spent on prescription drugs to control these markers aren’t making much of a difference.
Could we spend these research dollars more productively? I asked this question of Sumeet S. Chugh, MD, associate director of the Cedars-Sinai Heart Institute in Los Angeles. Dr. Chugh also is the director of the Oregon Sudden Unexpected Death Study, which researches risk factors, triggers and genetic defects that relate to sudden cardiac arrest.
First, some background. Much of what we know about Americans and heart disease was gleaned from the long-term Framingham Heart Study, which began in 1948. Hundreds of published studies have been based on this research. Though many consider it flawed in that the participant base consisted primarily of Caucasian men and women living in the New England area, in fact its findings were largely echoed by the 2004 release of the huge Canadian Interheart Study, which looked at heart attack risk factors from 52 different countries. Certain key risk factors for heart disease were found to apply to both genders and for all racial/ethnic groups:
- Abnormal levels of blood lipids (cholesterol and its various subtypes)
- High blood pressure
- Abdominal obesity
- Lack of regular physical activity
- Low consumption of fruits and vegetables
- Moderate alcohol consumption
- And finally, and not surprisingly, stress (for example, financial worries, combined with a life event, such as separation or divorce) often becomes a heart attack risk.
MULTIPLE CAUSES FOR HEART DISEASE
Over time, this research has been refined to arrive at our current understanding of cardiovascular disease as a multi-factorial condition. That is to say, multiple factors influence the development of heart disease and they contribute exponentially, not individually. Hence, a person who is overweight, sedentary, eschews fruits and vegetables and ends the day with a few martinis and regular arguments about money with his wife and kids becomes—almost certainly—a “ticking time bomb.” The good news is that the work of Dean Ornish, MD, founder of the Preventive Medicine Research Institute, and others has convincingly demonstrated that comprehensive lifestyle changes really can reduce the risk that heart disease will develop and sometimes can even reverse it. Nonetheless, the ongoing quest for the marker of the cause—and, of course, the highly profitable solution—continues.
WHAT DO MARKERS TELL US?
Blood cholesterol: The association between blood cholesterol and heart disease has been discussed, debated and fine-tuned for years now. While elevated cholesterol is a marker for heart disease risk, it seems that associated factors causing it to oxidize can trigger the formation of plaque. Cholesterol, therefore, is associated with—but doesn’t necessarily cause—heart disease.
C-reactive protein: The marker that most recently stirred up excitement was C-reactive protein, but Dr. Chugh told me that the more closely researchers examine its validity as an important marker of cardiac risk, the clearer it becomes that it isn’t particularly useful. He said it merely affirms what doctors are able to ascertain from measuring established risk factors. “It doesn’t tell us anything new—it may turn out to be just another test that is adding to health care costs,” he said.
Calcium score: Along the same lines, Dr. Chugh noted CT cardiac scans also may be more widely used than is necessary. “Calcium in plaque increases risk for heart attack,” he says, “but the ratio of cost and benefit for this test may not be optimal.”
Dr. Chugh notes that he does, however, continue to believe there are important markers of cardiovascular risk that research has yet to reveal. “There are markers out there that will come to light. We hope to find them,” he says. He believes the most promising avenue is genome research and says there now are searches underway for both protective and harmful genes.
In the meantime, Dr. Chugh emphasized that research continues to fine-tune advice about how we can lower cardiac risk. For instance…
- Quitting smoking really makes a difference. Smoking is known to lower HDL cholesterol, but the good news is that after you stop smoking, levels of the good HDL start to go up again.
- Start strength training. The new advice—more vigorous activity for less time (for example, jogging or running one hour and 15 minutes total a week—or 25 minutes three days a week) plus two sessions of strength training each week. “We now know you need strength training for increased muscle mass to help with balance and to facilitate your ability to exercise,” says Dr. Chugh.
- Diet is key. A Mediterranean diet still is considered just about the heart-healthiest way to eat, but the latest research confirms once again that it’s also important to keep calories under control. In addition to plentiful amounts of fruits and vegetables, Dr. Chugh says that omega-3 fatty acids in the diet from eating fish twice a week or through high-purity fish oil are considered beneficial.
Taking even one step toward improving your heart health will be of benefit. Dr. Chugh points out that if you correct just one risk factor, such as normalizing your weight or giving up junk food to help with your blood glucose levels, your prognosis will improve. This is because cardiac risk factors aren’t separate and unrelated—they expand exponentially. “It’s not just individual factors but the combination of the risks,” he says. “Go for whatever ones you can and by doing so you will decrease and even reverse overall risk.”