If you’ve had a coronary stent implanted or undergone bypass surgery, it is common to wonder about the status of the stent or the bypass grafts or the coronary arteries that maybe had a 50 or 60% blockage and were left alone.
This is especially likely if there was little or no warning that you had really severely blocked coronary arteries.
After all, you are thinking: “doesn’t it make sense to monitor these things and stay on top of them; be proactive?”
It certainly seems reasonable on the surface, and for many years, routine stress testing of patients without symptoms on an annual basis, was the norm.
However, this practice is much more likely to cause harm than to benefit patients and is recognized by the American College of Cardiology as one of 5 things that patients and physicians should question as part of the “Choosing Wisely” campaign (see here).
“Performing stress cardiac imaging or advanced non-invasive imaging in patients without symptoms on a serial or scheduled pattern (e.g., every one to two years or at a heart procedure anniversary) rarely results in any meaningful change in patient management. This practice may, in fact, lead to unnecessary invasive procedures and excess radiation exposure without any proven impact on patients’ outcomes.”
Studies have shown that stress testing less than two years after a coronary stent, very rarely change management.
The American College of Cardiology, American Society of Echocardiography and the American Society of Nuclear Medicine are all in agreement that stress testing less than two years after a coronary procedure is “inappropriate,” and more than two years after the procedure is “uncertain.”
Why Do Cardiologists Order These Tests If They Are Inappropriate?
There are 3 reasons, and they are representative of the major factors driving all over-testing in medicine.
- Financial. Cardiologists frequently benefit from stress tests they order in multiple ways. First, they may own the nuclear camera used in the test and the more stress tests performed in their office, the more money they will make from the technical remuneration for the procedure. The cardiologist also frequently interprets the test results and receives a professional fee for both supervising and interpreting the nuclear images. Finally, if the test is abnormal, the cardiologist may then recommend additional testing, which he may perform (cardiac catheterization, stent) or interpret (coronary CT angiogram).
- Defensive medicine. It is not uncommon for cardiologists to be sued for NOT performing a test or procedure when the patient’s outcome is bad. On the other hand, I have never heard of a cardiologist being sued for DOING an inappropriate stress test.
- Keeping the customer happy. Too often patients feel that if their doctor is performing frequent tests on them, he is being vigilant, proactive and “staying on top of things.” They don’t realize the down sides to the extra testing and the lack of benefit.
Not uncommonly, patients switching to me from another cardiologist indicate that they have been getting an annual stress test and are disappointed to hear that I am not recommending one.
They may think that I’m lazy or not up on the latest techniques in cardiology. Usually in this situation I have to spend a fair amount of time trying to teach them about the possible downsides of over-testing.
In the case of stress nuclear testing, harm comes from two sources:
- Radiation. Stress nuclear tests typically utilize the radio tracer Technetium-99 and result in a radiation dose of around 15 mSv. This is about 10 times the radiation from a typical coronary calcium scan. A chest x-ray gives 0.02 mSV and the annual background radiation in the US is 3 mSv.
- False positives. Nuclear imaging is very susceptible to images which appear to show abnormalities of blood flow, which in reality are just due to soft tissue (breast, diaphragm, fat) interposed between the heart and the camera. These can be interpreted as due to a heart attack or blocked coronary artery when everything is actually fine with the artery. False positives then lead to additional testing such as a cardiac catheterization, which carries risks of bleeding, heart attack, stroke and death.
One important point to remember is that coronary stenting has not been shown to reduce heart attacks or prolong survival outside the setting of an acute heart attack. Therefore , if you’ve already had a cardiac catheterization that either resulted in bypass surgery or a stent of one artery, it is highly unlikely that a subsequent catheterization/further procedures will lower your heart attack or dying risk.
Certainly, if you have a change in symptoms that suggest that your coronary artery disease has progressed, this is an appropriate reason to consider stress testing. Such symptoms include shortness of breath on exertion and chest discomfort, especially if it occurs during activity. Diabetics often don’t have symptoms that warn them of a problem, therefore, we should consider stress testing more frequently and at a lower threshold for them.
For most people, however, more is not always better when it comes to cardiac testing and, in many circumstances, can be worse.
Here’s to choosing wisely,