Doctor’s Tip: February is heart month — do you know if your coronary arteries are healthy?
Heart attacks are the leading cause of death in the U.S. We know what the risk factors are: hypertension; smoking; age (male over age 40, female over age 50); family history of heart disease or strokes; high cholesterol; pre-diabetes and diabetes; central obesity (extra weight around the middle); sedentary lifestyle; the Standard American Diet; sleep issues including apnea; inflammatory diseases such as rheumatoid arthritis and dental inflammation; high Lp(a) — a particularly harmful type of bad cholesterol; small LDL particle size; and depression and other emotional stress.
While these factors are important in determining a person’s risk for a heart attack, what heart attack prevention doctors (usually not cardiologists, with some notable exceptions such as Dean Ornish, M.D.) really want to know is what your arteries look like. Heart attacks only occur in people with atherosclerosis (hardening of the arteries) — although most people on a Western diet eventually develop it.
The inside of arteries is lined by an organ called the endothelium, which should remain 0.5 mm thick throughout life. If the endothelium is stressed over the years by bad genes, bad habits such as smoking, or conditions such has hypertension or high cholesterol, the lining thickens. Eventually plaque (atherosclerosis) forms, 99 percent of which is in the wall of the arteries, not causing a blockage. If plaque in a coronary artery ruptures, often caused by inflammation, the resultant blood clot blocks the blood supply to part of the heart muscle, resulting in a heart attack. If this happens in the brain, a stroke (brain attack) occurs.
In some 20 percent of heart attack victims, the first symptom is the last: sudden death. In other words, these people had no clue they had atherosclerosis and were at risk. So it would be nice if we had a screening test for artery health and indeed we do — a carotid IMT (note EKGs and stress tests are usually not helpful). An IMT is a painless, non-invasive doppler study of the carotid arteries in the neck. The report indicates the thickness of the endothelium as well as whether or not plaque is present (defined as any localized thickening of 1.2 mm or greater). If plaque is present, the report indicates whether it is the more stable, calcified plaque or the less stable uncalcified variety — which is more vulnerable to rupture.
Unfortunately, only a small minority of doctors order this valuable test, and many of the ones who do don’t interpret it correctly. According to Bale and Doneen in their book “Beat the Heart Attack Gene,” if the vascular age based on the endothelial thickness is 8 years or greater than a person’s actual age, they are at significant risk for a cardiovascular event (heart attack or stroke). If plaque is present, this always trumps endothelial thickness. So, for example, if a 50-year-old woman has a vascular age of 53 on an IMT study but has plaque, she is at significant risk for a cardiovascular event (heart attack or stroke). She should be treated aggressively with lifestyle modification and/or medications such as statins. If the study is repeated after a year of appropriate treatment, the endothelial thickness should improve and the amount of plaque should be the same or less.
If a carotid IMT is abnormal, that can be very motivating to the patient to make necessary changes — for example if a 50-year-old man has the arteries of a 70-year-old. There is no perfect test in medicine, and the IMT looks at the carotid rather than the coronary arteries. But there is a 95 percent correlation between the two. If a patient with risk factors has a normal IMT, then they might be in that 5 percent non-correlation group, and a coronary calcium score should be considered, which is a CT scan of the heart. If any calcium shows up, that person is at risk, although false negatives can occur particularly in young people, who are more apt to have uncalcified (soft) plaque. This test is not useful for following effectiveness of treatment, and should not be repeated — it involves radiation, plus if a repeat calcium score is higher, that could be a good thing if soft plaque has become calcified/stabilized.
Carotid IMT is FDA approved and has been used for decades in research studies. In “Beat the Heart Attack Gene,” Bale and Doneen note that “a recent study of more than 13,000 men and women found that adding intima-media thickness and the presence of plaque to traditional risk factors significantly improved the accuracy of 10-year predictions of heart attack and stroke risk.” Because atherosclerosis is so prevalent in Americans, and because it is potentially fatal, Bale and Doneen feel that anyone age 40 or over should have an IMT, and people with conditions such as pre-diabetes or diabetes should have an IMT at 30. The only place I know of that does IMTs is Glenwood Medical Associates (note I have no financial interest in this).
Dr. Feinsinger, who retired from Glenwood Medical Associates after 42 years as a family physician, has a nonprofit Center For Prevention and Treatment of Disease Through Nutrition. He is available for free consultations about heart attack prevention and any other medical concerns. Call 970-379-5718 for an appointment. For questions about his columns, email him at firstname.lastname@example.org.
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