Doctor’s column: What causes a heart attack
Heart attacks are the leading killer in Western countries, among both men and women. In the U.S., more than 500,000 people die every year from heart attacks, and in about 20 percent of those, the first symptom is the last. In other words, they had no clue that they had heart disease and died suddenly.
To understand what causes heart attacks, you first need to know that the endothelial lining of the arteries is a very important but very delicate organ system that would cover two tennis courts, and in order to stay healthy it should remain 0.5 millimeters thick throughout life.
If it is stressed, by bad genes, bad habits such as smoking, and/or conditions such as hypertension, high cholesterol or diabetes/pre-diabetes, the first thing that happens is that the endothelium thickens. Eventually, cholesterol-laden plaque forms in the wall of the arteries, called hardening of the arteries or atherosclerosis. Ninety-nine percent of plaque in the wall of the arteries does not cause an obstruction, so only 1 percent is obstructive plaque.
What actually causes a heart attack is when plaque in the wall of the artery ruptures, often driven by inflammation. A blood clot then forms, blocking off the blood flow, causing a heart attack if it is in a coronary artery or a stroke if it is in a brain artery.
The risk factors for developing atherosclerosis and therefore heart attacks are:
• Age (male over 40, female over 50).
• A personal history of a heart attack or stroke (i.e. if you have had a heart attack or stroke, you are at much higher risk for another one versus someone who hasn’t).
• A family history of atherosclerosis/heart attacks or strokes.
• High total or LDL (bad) cholesterol, high triglycerides, low HDL (good) cholesterol.
• Diabetes, pre-diabetes.
• Sedentary lifestyle.
• The S.A.D. (Standard American Diet).
• Sleep apnea and other sleep disorders.
• Migraine headaches.
• Emotional stress including depression and anxiety.
• Inflammation, such as inflammatory diseases like rheumatoid arthritis.
• Dental/gum disease.
The more of these risk factors you have, the more apt you are to have atherosclerosis and to therefore be at risk for a heart attack. There are calculations that some think are valuable, such as the Framingham Risk Score that attempts to assess the likelihood that someone is going to have a heart attack in the next 10 years, but such calculations can be dangerously misleading.
What heart attack prevention doctors want to know is whether you have atherosclerosis, because if you don’t, you aren’t at risk for a heart attack. But if you have even a little, you are at risk and need to be treated aggressively.
What many of us use to make this determination is a carotid IMT. This is a 10-minute, painless, noninvasive Doppler study of the carotid arteries in your neck. It looks at the thickness of the endothelial lining and picks up plaque as well. The downside of this test is that it looks at your carotid rather than your coronary (heart) arteries, but there is a 95 percent correlation between the two.
If the IMT is normal, but we still suspect you have atherosclerosis, we think you may be in that 5 percent group with no correlation, and then we order a coronary calcium score, which can be obtained for around $100 at Community Hospital in Grand Junction. This is a CAT scan of the heart, so in contrast to the IMT, it does involve radiation. This test tells us how much calcium and therefore how much atherosclerosis you have in your coronary arteries. The downside of this test is that it misses dangerous, uncalcified plaque, and therefore can be misleading, particularly in younger people, who often have not yet calcified their plaque.
In the next column, we will discuss how to prevent heart attacks. Almost all heart attacks can be prevented, but unfortunately many aren’t.
Dr. Feinsinger is a retired family physician who is available for free consultations about heart attack prevention, plant based nutrition, and other health issues. Call 379-5718 for an appointment.
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