DR. HARRINGTON: We really could be talking about whether we should perform routine stress testing in asymptomatic individuals, but maybe there are some qualifiers.
If we decide that a person needs an exercise or a stress test, what method should we use to decide upon it? I agree with you that we underutilize ECG stress testing, by far, and all that we can learn from it. The default practice in many ways is to directly opt for stress imaging, and I suspect we will discuss that as well.
DR. ALPERT: One of the things I want to point out is that in decision analysis and Bayesian thinking, the less common the illness in the population being tested, the more likely is the possibility of false positives than true positives or an equal number of true and false positives. And, so, in an asymptomatic population that doesn’t have a very high incidence of the disease, one will consequently see a high number of false positives, and many patients will have a cardiac catheterization that they might not have needed.
Admittedly, cardiac catheterization is quite safe, but I remember a case at the University of Massachusetts with Dr. Harrington, when we catheterized the brother-in-law of a staff member, who kept coming to the emergency room with atypical chest pain despite negative exercise tests. During the procedure, a small atheroma traveled to his brain; it led to internuclear ophthalmoplegia, and he couldn’t work for 6 months.
We all were at such a loss, because although the patient did go on to have normal coronaries, we shouldn’t have performed a coronary angiography. So, I think that, each time we order a test, we should ask ourselves “what are we going to do if the outcome is such and such versus something else?” just as Dr. Harrington said.
Well, let’s talk about some special subsets. Let’s first talk about routine patients following angioplasty or bypass surgery, 6 or 8 months down the road. Do you think they ought to have an exercise test done to see how adequate the intervention has been?
DR. HARRINGTON: We know the answer to that one, Dr. Alpert, because there have been randomized clinical trials,2 and the answer is a resounding “no.” In the absence of symptoms, after a revascularization procedure, one should not routinely perform exercise tests, because the added information is not helpful.3
DR. ALPERT: Do you agree, Dr. Amsterdam?
DR. AMSTERDAM: I agree. I know of an individual who had bypass surgery about 10 years ago. He plays tennis, works full-time, is asymptomatic, and undergoes yearly stress myocardial perfusion testing. This abuse of testing is not rare.
DR. ALPERT: Here, in Arizona, there are a lot of snowbirds. Many of my patients see me once during their 4 or 5 months in Arizona. They come in and say, “Okay, my doctor said I could have my annual stress test here this year.” Then we have to have a conversation in which I say, “I don’t do routine stress tests every year.” Then I explain to them that if they’re vigorous and active and they’re not having symptoms, it’s very unlikely that the information will help us in any way, and it may actually end up leading to some harm.
Now, let’s talk about the definition of asymptomatic. Do we believe he/she is asymptomatic if the patient says “I never have symptoms” or do we have to dig further?
DR. AMSTERDAM: Aortic stenosis (AS) is a very good example. I think of where we’ve come from years ago, when we didn't do stress testing in patients with critical AS. But, with echocardiography, we can identify critical AS in patients who, by history, are asymptomatic. But, sometimes we can’t be sure about their level of activity or inactivity. In those cases, a supervised treadmill test is appropriate, safe, and informative, and may uncover symptoms at low exertion levels, inadequate rise in blood pressure, or ischemic ST segment changes, and these findings play an important role in the decision of whether or not to consider intervention for the AS.
DR. ALPERT: Dr. Harrington, do you agree?
DR. HARRINGTON: There’s a whole body of literature on the regurgitant lesions,4 including reports on patients with stenotic lesions that Dr. Amsterdam specifically talked about. Stress testing is used as a way to understand the pathobiology of the valve and whether or not it’s time to think about intervention for that valve. That gets us into a complex area regarding how one utilizes the results of stress testing to guide the management of patients with valve disease.
But I think more broadly, Dr. Alpert, that your initial question is “How do we assess an asymptomatic state, and are there various degrees of asymptomatic states?” I think the answer to that resides in a careful history and physical examination. If, for example, our physical examination uncovers a very sedentary lifestyle for somebody who now wants to embark upon an active exercise program, and this person has multiple cardiac risk factors, which are perhaps not well managed, an exercise test as a prelude to exercise, or an exercise prescription, might well be a reasonable way ahead. That would be an example of an asymptomatic patient that would need to be evaluated further.
Dr. Amsterdam has mentioned the valve disease patient that we might manage with stress tests. I would add that we consider patients as asymptomatic until we start taking their histories. Then, we begin uncovering facts that might lead us to investigate the patient and even look for symptomatic coronary disease. So, I do think it’s not something to use routinely. We should rely on our history and physical examination, and there are indications for which we might want to pursue stress testing in selected individuals.
DR. AMSTERDAM: We can certainly do better at history taking, but, as you said, exercise or stress testing is an extension of the history and physical examination that can fine-tune our clinical assessment. For example, exercise testing quantifies patients' functional capacity, and it is not uncommon to find a considerable disparity between a patient's history of physical examinations and what he is actually able to do on testing, with the latter being commonly far less.
DR. ALPERT: As I was sitting here, I was thinking about my days as a student, resident and fellow. Lewis Dexter, who, of course, is one of the great pioneer cardiologists of the 20th century, was my teacher and professor. He would often talk about patients with mitral stenosis. In those days, we had so many of them because Dwight Harken was at the Brigham performing 2 or 3 mitral valvuloplasties a day.
In those patients, Dexter always emphasized that it was important to have the spouse or friend there with the patient, because you would ask questions like “Have you had any shortness of breath when you exert yourself or when you’re doing housework?” The patient would say “no,” and the spouse would say, “No, they’re not doing anything, they’ve stopped all exertion. They’ve stopped making the beds in the morning. They’re not vacuuming. They’re basically just sitting around all day.” Of course, mitral stenosis was mostly seen in women.
I remember Dexter would often say to the patient, “Okay, let’s go out and walk down a flight of stairs and up a flight of stairs.” And when the patient would get down 3 or 4 stairs and had to stop because of dyspnea, you knew that the story was very different from what the patient was saying. So, it often helps to have corroboration. Again, when you think that the patient may not be giving you the true story, I think that’s an indication for an exercise test as well.
DR. HARRINGTON: I think that Dr. Amsterdam’s comment that it can be an extension of our history taking and physical examination is an important comment. I think of it with regard to patients who are referred to us and want to begin an exercise program. Many of us, when we reach middle age, decide that we need to improve our exercise habits. As you start to uncover things from a history, which might concern you a bit, or if you want to lay out the exercise prescription safely for a middle-aged person with important risk factors, I think it can be an important addition to our history and physical findings.
In that case, you’re absolutely taking full advantage of everything the exercise test offers: How far do they go? What happened to their heart rate? What happened to their blood pressure? Do they have any symptoms that limit them? What did their ECG look like? There’s a lot of information to gain from the exercise test that is often not considered.