The past 45 years have seen a revolution in the management of heart disease. By far the most common form of heart disease is coronary artery disease, in which atherosclerosis damages the coronary arteries (the arteries that feed blood to your heart muscle). Coronary artery disease is responsible for nearly half of the deaths of older Americans. However, scientists now view atherosclerosis as a preventable illness.
What is atherosclerosis?
Atherosclerosis means “hardening of the arteries”, where blood fats become deposited in the walls of larger arteries. The arterial wall becomes inflamed, thickened, and stiff. Usually this process requires decades to progress, but under certain circumstances, it can happen in months or a few years. The early stages of atherosclerosis are mostly silent; you don’t become ill until the disease has become advanced. Then two things can happen.
First, the mass of fatty deposits and scar tissue within the arterial wall can be so thick it narrows the inside of the vessel and impairs the flow of blood. The tissues downstream of this artery become ischemic (starved for oxygen) and start to malfunction. If this is your heart, you may develop angina, or chest pains due to inadequate blood supply. In your brain, you may have transient ischemic attacks, or temporary periods of weakness or numbness in one area of your body. Poor blood supply to a kidney can cause high blood pressure and kidney failure (your kidney doesn’t clean the blood adequately). The same sort of arterial narrowing can affect your legs, your intestines, and other parts of your body.
The inflammation of atherosclerosis can also damage the blood vessel wall. A sudden blood clot may form that completely shuts off blood flow and kills the tissue supplied by the blood vessel. In your heart, this is a heart attack: a portion of the heart muscle dies from lack of blood. Or, equally likely, you can die suddenly and without warning. A blood clot blocking an artery in your brain causes a stroke. Other organs can also be damaged by lack of blood supply.
While the portions of arteries that have been severely narrowed by atherosclerosis are at risk for developing an occluding blood clot, in fact such a clot often occurs in areas that are only mildly narrowed. So just treating severely narrowed arteries does not remove the risk of atherosclerosis.
Atherosclerotic damage to the blood vessel can also cause it to enlarge like the bleb on a worn-out tire (called an “aneurysm“). This occurs most commonly in the aorta, the main artery arising from the heart that travels through the inside of the chest to the lower abdomen. Aortic aneurysms rarely cause symptoms until they rupture, but then the death rate from loss of blood is very high.
Current thinking on atherosclerosis is if you develop atherosclerosis in one area, it’s present everywhere in your body. It may affect multiple organs at once. So the new perspective is that atherosclerosis is a systemic illness: it affects all of you. Therefore it must be treated systemically: your whole body at once.
What causes atherosclerosis?
Atherosclerosis occurs when excessive cholesterol and other garbage is deposited in the inner walls of your arteries, which then become inflamed. Age is the most important factor determining your risk of atherosclerosis: over 50 for men and over 65 for women. But smoking greatly accelerates atherosclerosis, so it occurs at a much younger age. The same is true of diabetes, high blood pressure, and severe elevations of cholesterol. Other factors can damage your blood vessels too: obesity, extreme stress, a high-fat or junk-food diet, and lack of exercise.
How does atherosclerosis affect the heart?
Atherosclerotic heart disease (ASHD) has been the biggest killer of Americans for several generations. Also known as “coronary artery disease,” it’s responsible for the deaths of 900,000 Americans annually.
The current death rate is 30% lower than it was a generation ago.
Curiously, more women (500,000 annually) are dying per year than men (400,000). Though women rarely develop ASHD before age 65, they often have unusual symptoms like shortness of breath and fatigue, rather than chest pain. So it can be hard to tell when a woman is in the early stages of heart disease. By the time it’s clear something is wrong, their illness is harder to treat.
Usually, you find out you have coronary heart disease without warning: you drop dead, have a heart attack, or develop angina. Each is equally likely. My patients agree dropping dead or having a heart attack is bad for you. We’d all like to be able to prevent such a sudden catastrophe.
Here’s the good news: techniques developed in the last 10-20 years can detect the increased risk of heart disease in many people. Targeted treatment can then lower the risk of a cardiac event by 40-80%.
Preventing destructive cardiac remodeling
Sometimes people with heart disease develop one complication after another, moving from disaster to disaster. We’ve learned that much of the problem occurs long before patients develop symptoms: the heart is damaged by elevated blood pressure, high blood sugar, stress, and cholesterol in ways that make it much more likely to be harmed by any subsequent events. For example, one of the earliest changes is that heart muscle walls become stiff and don’t relax enough to let the blood flow freely into the heart between contractions. As stiffness progresses, the heart enlarges and doesn’t empty well when it does contract. As a result, the heart does an increasingly poor job of its essential function: pumping the blood. People start to feel tired for no obvious reason and restrict their activity. But excessive rest is bad for the heart, and so a series of vicious cycles ensues.
Preventing this cascade of bad news requires detecting problems and intervening before they become obvious. Early destructive remodeling responds to effective treatment, but the longer you wait, the more likely harmful cardiac remodeling has become permanent.
The key to lowering your risk of heart disease is to determine how much risk you have now — none, low, intermediate, high, or severe — before you develop symptoms. Then we match treatment to the degree of risk. No risk means no treatment. If your risk is low, lifestyle modification (exercise, diet, etc.) may be the only approach you need. High levels of risk requires intensive treatment. Physicians have moved away from testing just cholesterol or just blood pressure to determine your risk. The science is clear that overall risk is the best predictor of outcome. So you look at risk as a whole and treat what you see.
Most people who develop heart disease have factors that predict they are likely to have a problem. Here are the basic risk factors.
- Previous heart attack or other clear-cut heart disease
- Uncontrolled high blood pressure
- Impaired kidney function (measured with a blood test)
Moderate risk factors include:
- Family history of early heart disease
- Abnormal cholesterol or other blood fat levels
- Obesity (particularly around your middle)
- Atherosclerosis (hardened, narrowed arteries) elsewhere in your body
- Lack of exercise
- Elevated blood sugar not high enough for a diagnosis of diabetes
- Metabolic syndrome (includes several of the other factors but is also important by itself)
Some people who have a heart attack never had any risk factors, but usually several have been present for some time. Thankfully, of all the risk factors just listed, there are only a few you can’t improve.
Estimating Risk Severity
The best quick estimate of the likelihood of a cardiac event (heart attack, sudden death, or chest pain) is the risk calculator from the American College of Cardiology and the American Heart Association. You’ll need to know your age, gender, blood pressure, smoking status, total and HDL cholesterol levels, and whether you have diabetes. You can play with the numbers to see the effect on your risk.
Refining Your Risk Estimate
Performing a history and physical exam may pick up early indications of atherosclerosis. Curiously, there’s now evidence that doing a routine electrocardiogram in a healthy patient can turn up an innocent abnormality in the tracing, i.e., a “false positive,” that can trigger an expensive and potentially risky wild goose chase. Most other screening methods in healthy patients probably also bring too high a risk of false positives. So don’t pursue further screening unless you have symptoms that concern you. Age, blood pressure, blood sugar, cholesterol level, and the other factors listed above probably suffice.
How Do You Lower the Risk of Heart Disease?
Several individual treatments can each lower the risk of having a cardiac event by 10-60%. None by itself is a slam-dunk, but when you add them together, their benefit is impressive. The higher your risk, the more treatment you’ll need to remain healthy:
1. The single most effective treatment is taking a statin type cholesterol-lowering drug. Trade (generic) names include Mevacor (lovastatin), Pravachol (pravastatin), Zocor (simvastatin), Lescol (fluvastatin), Lipitor (atorvastatin), and Crestor (rosuvastatin). These medications cut your heart disease risk by 30-50%. They work better than any other cholesterol-lowering drug, but can cause side effects. The old idea that you treat cholesterol levels in isolation has been discarded in favor of treating overall risk regardless of the cholesterol result. This is because many heart attacks occur in people with cholesterol levels that seem perfectly okay, but their risk is high.
2. If your blood pressure is high or your risk is at least intermediate, you should be on treatment to lower it.
3. Lifestyle changes are critical to lowering your heart disease risk. Stopping smoking is the single most important thing you can do for your health. Though it’s often difficult to lose weight, changing your diet (more fresh vegetables and fruit, less animal fat, less junk food) produces enormous health benefits. Modest exercise reduces your heart disease risk by 50%, improves function, and dramatically lowers the risk of virtually every illness.
Treating According to Risk
Once you know your level of risk (none, low, intermediate, high, severe), tailor treatment to your risk:
- None: Go walk in the sunshine. You don’t need any treatment per se, but for heaven’s sake, if you smoke, stop.
- Low: Improve your lifestyle — smoking, diet and exercise.
- Intermediate (two or three risk factors): In addition to the lifestyle changes just mentioned, be sure your blood pressure is well controlled, and use a statin drug.
- High or severe (multiple risk factors): You need lifestyle changes, a well-controlled blood pressure, and a high-dose statin drug.