I frequently perform emergency procedures to open up blocked heart arteries. At the end of the case, I’m often asked by the patient “how could this happen, I only just had a normal stress test a few months ago!” They think they have either been mismanaged by their cardiologist, or that the test was read wrong. But really, the problem is the lack of understanding about the information a stress test provides in patients with heart disease. So should you ask “do I need a stress test?”
Heart Attack vs. Stable Heart Disease
Heart attacks occur when an unstable area in an artery wall bursts and leads to clot formation. The clot that forms, leads to critical blockage of the artery, cutting off the blood supply beyond that point. The heart muscle supplied by that artery now no longer gets the blood it needs, and dies, typically within a matter of hours. This is why a heart attack is the most feared complication of coronary artery disease.
Most heart related chest pain however is not from a heart attack; it is the kind that comes with exercise/exertion and goes with rest. This is typically called stable heart disease and is the result of blockages that have formed over time and limit blood flow to the heart muscle causing the symptoms at times when increased blood flow is required, such as exercise or walking up stairs.
So What Does A Stress Test Tell Us?
Although there are many different types of stress test, they have the same goal in common, to look at the blood supply to the heart. By comparing the blood supply in different areas, the stress test highlights the areas where artery blockage is tight enough to prevent the heart muscle getting the blood supply it needs to meet its demands.
In people with symptoms such as chest pain on exertion, the stress test can often identify the area where the blockage is, and also give information about the extent of the problem, information that can be used to guide our management of these patients. So in patients with symptoms, the use of the stress test is clear, to identify the area blocked, and use that information to guide treatment that may include the use of medications, or even an invasive procedure such as a heart catheterization to have a closer look.
It’s Often The Silent Abnormality That The Stress Test Can’t Pick Up That Causes Heart Attacks!
This is where it gets interesting, as it’s often the people with no significant blockages or symptoms that can get heart attacks. Ideally we would have a test that would identify the ‘unstable lesion’ basically the area that is likely to burst and cause a heart attack. However this is often the area that is not causing a significant blockage that limits blood flow. Infact it is often the silent yet deadly area that can look relatively normal, even if we did an invasive test such as a heart catheterization. The stress test wouldn’t even begin to identify such patients and would come back as normal. As of yet, we don’t have a test that is proven to accurately identify unstable lesions. We do however have measures that can help stabilize heart disease such as the use of proven medications, life style changes, and the modification of risk factors such as high blood pressure.
So Who Might Need A Stress Test
In patients with ongoing symptoms, especially high risk patients with a history of heart problems, stress tests may be useful to identify whether there are significant blockages in the arteries that are the cause of the problems, and help guide further management. In some cases such as in patients deemed at very high risk by a cardiologist, or in patients with unstable symptoms it may be reasonable to skip the stress test and proceed straight to heart catheterization and have a look at the arteries.
However in most patients that are not having symptoms or ongoing active heart issues such as worsening shortness of breath, there is usually no indication for a stress test. In fact the overuse of these tests may cause more harm than good by leading to unnecessary and risky procedures. It’s reasonable to suggest that if a patient truly has a blockage that needs identifying, there would be symptoms in most cases.
Stress Tests Are Commonly Overused
Recent studies have highlighted the overuse of stress tests. Many studies have demonstrated the remarkable overuse of these tests simply by the very high rate of completely normal tests, many of which never needed doing in the first place. In patients that have had stent placement or bypass surgery for example, it has been demonstrated that routine testing in most patients without symptoms was associated with increased risk of repeat procedures, but no decrease in the rate of heart attacks or death.
In fact routine yearly tests for most stent or bypass patients without symptoms is no longer recommended. In patients who develop symptoms, heart issues, or deemed by their physician to be at high risk, the use of stress testing may be reasonable.
It’s Important To Concentrate On The Key Issues
Unfortunately the false reassurance from unneeded routine stress tests in patients without symptoms often appears to make people forget that the emphasis in these patients should be on treatments that can act to stabilize the heart disease. These treatments include medications, blood pressure control, cholesterol management, avoiding smoke, exercise, diet, and adoption of a healthy lifestyle. Now these are truly life-saving measures.