An Incipient Threat to Our Hearts
NOVEMBER 17, 2014 10:24 AMNovember 17, 2014 10:24 am 19 Comments
Jane Brody on health and aging.
Millions of Americans are walking around with deposits in their coronary arteries that do not obstruct blood flow to their hearts — at least, not until a piece of the plaque ruptures and forms a blood clot, causing a heart attack.
These plaques are signs of a condition called nonobstructive coronary artery disease, and they are found in 10 percent to 25 percent of patients who have a coronary angiogram, typically done for patients with symptoms like chest pain or shortness of breath or those who flunk a cardiac stress test.
Historically, doctors have considered the partial obstructions insignificant, and a surprisingly large percentage of patients with them are sent home without treatment. Often patients are given “the good news that they don’t have a coronary blockage,” said Dr. Thomas M. Maddox, a cardiologist at the Veterans Affairs Eastern Colorado Health Care System and the University of Colorado in Denver.
Sadly, the news isn’t really good. By some estimates, the majority of heart attacks result from these nonobstructive lesions. Four years ago, Dr. Maddox and his colleagues published a study of nearly 1.5 million patients with varying degrees of coronary artery disease. Compared with those who had major obstructions in their coronary arteries, patients with nonobstructive lesions were less likely to be prescribed therapy with aspirin, a statin or other drugs to reduce their heart attack risk.
This month, Dr. Maddox and co-authors published a study in JAMAgraphically demonstrating the sometimes devastating consequences of ignoring nonobstructive coronary disease, especially in patients with symptoms.
The researchers gathered data on 37,674 veterans without known coronary artery disease who underwent elective angiograms between October 2007 and September 2012 in the Veterans Affairs health care system. Fifty-five percent were found to have obstructive coronary disease, and 22 percent had nonobstructive disease. The risk of having a heart attack or dying within one year was directly related to the extent of disease in the participant’s coronary arteries. As expected, the risk was greatest among patients who had obstructive coronary disease, defined as a blockage equal to or greater than 70 percent in one or more coronary arteries.
But the prognosis for patients with nonobstructive disease was hardly benign.
Compared with those who had no evidence of coronary artery disease, or CAD, the risk of suffering a heart attack within just one year of the exam was doubled in patients with nonobstructive CAD in one artery, and more than four times greater in those with nonobstructive disease in two or three arteries. The death rate increased with the extent of nonobstructive disease.
“These findings highlight the need to recognize that nonobstructive CAD is associated with significantly increased risk for myocardial infarction,” or heart attack, Dr. Maddox and his colleagues concluded.
The researchers spurned the traditional distinction made between nonobstructive and obstructive CAD, and suggested that all patients with nonobstructive disease would likely benefit from drug treatment — although no randomized clinical trials have yet been done to support this recommendation. (In particular, stents have not been shown to be an effective preventive for such patients.)
“If we did an angiogram on every adult, a significant number would be found to have nonobstructive disease and be at risk of a heart attack,” Dr. Maddox said in an interview. “If an angiogram shows a blockage of 30, 40 or 50 percent in one or more arteries, the patient should be on preventive therapy.”
He does not recommend routine angiograms, however, which are costly and have risks of their own. On rare occasions, they can cause bleeding, infection, damage to blood vessels, or an allergic reaction to the dye used. Alternatively, patients can choose a noninvasive test, like a coronary calcium score or CT angiogram.
Heart disease is linked to a slew of risk factors: smoking; being overweight, obese or physically inactive; having high cholesterol, high blood pressure, Type 2 diabetes or pre-diabetes; a family history of heart disease before age 65; consuming an unhealthy diet; and being 55 or older. Chronic stress also has been linked to heart disease.
Doctors usually advise patients at risk to modify their living habits. If they smoke, they should stop — within as little as a year, their coronary risk can drop to that of a nonsmoker.
Those who are overweight may be told to cut down on fattening foods, eat more fruits and vegetables, and to exercise more, measures that help lower body weight and cholesterol and help control high blood pressure and diabetes.
If high cholesterol is a problem, saturated fats like dairy and meat fat should be reduced, and unsaturated olive or canola oil used when fat is needed.
Some of this advice was given to my father in 1979 after he suffered a heart attack at age 58. He never smoked, was already active and not overweight. He modified his diet, which helped to keep him alive for 13 more years. But lacking anything more to do to protect himself, he succumbed to a second heart attack at age 71.
Now there is proof that certain medications can ward off even a first heart attack in people at risk. The two most commonly recommended are a daily baby aspirin and a statin.
Aspirin thins the blood, reducing the risk that a blood clot will form in a coronary artery. The Food and Drug Administration does not recommend daily use to prevent a first heart attack — but some doctors do. Possible side effects include an increased risk of gastrointestinal bleeding.
A statin, though primarily prescribed to lower blood levels of artery-clogging cholesterol, turns out to have cardiac benefits beyond slowing the formation of new plaques in coronary arteries.
Statins sometimes reduce the size of existing lesions. They can suppress inflammation that contributes to plaque formation. They improve the function of cells that line the arteries, enabling them to expand as needed.
Statins may also stabilize plaques, reducing the chance that they will rupture and block arteries feeding the heart.
Given these benefits and the fact that plaque rupture is the source of 95 percent of heart attacks, Dr. Maddox said that if he had coronary artery disease and was stranded on a desert island, the one drug he would want to have with him is a statin.