October 27th, 2014
Case: When an “Inappropriate” Stress Test Might Be Appropriate
Jean-Pierre Usdin, MD and James Fang, MD
A 58-year-old male gynecologist with well-treated hypertension and no symptoms wants to start exercising and asks his cardiologist to give him a stress test. He is a nonsmoker, has a normal BMI, and does not take aspirin. He has never had a coronary angiogram. The patient’s cardiologist asks him to discontinue his acebutolol, which he takes for the hypertension, so that he can undergo an “unmasked” exercise stress test. The patient discontinues the medication on the morning of the test.
The stress test results are normal, and the patient feels reassured. He recovers for a few minutes, showers, and is sent home with a green light to exercise. Before he even exits the hospital, however, he begins to experience chest heaviness, nausea, and sweating.
He returns to the cardiology department, where he is found to have low blood pressure and a slow heart rate, initially thought to be a delayed vasovagal response to the stress test. However, an ECG shows an ST-segment-elevation MI in the inferior leads. Prompt catheterization reveals a huge thrombus in the right coronary artery.
The patient undergoes immediate, successful primary PCI and stent placement, and he is admitted to the CCU. On day 3, he is discharged in good condition with prescriptions for aspirin, prasugrel, acebutolol, and atorvastatin.
Questions:
- Could the exercise stress test have caused this patient’s MI (by provoking a rupture in a plaque that is presumed to be stable but turns out not to be), or was the MI inevitable — and more likely to be fatal if it had happened outside the hospital?
- Would it have made any difference if the patient had been on aspirin or hadn’t stopped his beta-blocker?
- Would the patient-requested stress test have been considered “inappropriate” in this case, even though it helped to prevent a potentially fatal event? (See the recent CardioExchange discussion on this topic.)
- Should people at high risk for ACS events take aspirin before exercising? What about healthy individuals and athletes (e.g., marathon runners) who are about to engage in intense activity?
Response:
November 3, 2014
1. Could the exercise stress test have caused this patient’s MI (by provoking a rupture in a plaque that is presumed to be stable but turns out not to be), or was the MI inevitable — and more likely to be fatal if it had happened outside the hospital?
MI is a known but rare complication of exercise stress testing (the risk is likely less than 1 in 1000, according to multiple large series). Possible mechanisms include increased shear stress at the point of modest plaques, increased thrombogenic milieu related to the increased adrenergic environment, and previously asymptomatic high-grade lesions leading to supply-and-demand mismatch. But it is at best speculative to suggest that the stress test “caused” the MI. It is also difficult to say the MI was “inevitable,” but no doubt the patient was at risk given his CV risk factor(s). Having an MI in a medical environment can expedite diagnosis and therapy, although paradoxically hospitalized patients often have greater door-to-balloon times because the MI may not be recognized.
2. Would it have made any difference if the patient had been on aspirin or hadn’t stopped his beta-blocker?
Aspirin and beta-blockade may have had some effect, in the context of the pathophysiology of STEMI, but it appears that the patient had underlying CAD. Withholding the beta-blocker to improve the sensitivity of the test helps only to identify flow-limiting lesions and would not improve the accuracy of diagnosing less severe coronary atherosclerosis.
3. Would the patient-requested stress test have been considered “inappropriate” in this case, even though it helped to prevent a potentially fatal event? (See the recent CardioExchange discussion on this topic.)
I do not believe that this stress test was “inappropriate” because this scenario is a guideline-recognized indication — i.e., testing sedentary people before initiating a rigorous exercise program. Interestingly, concomitant imaging does not appear to have been ordered.
4. Should people at high risk for ACS events take aspirin before exercising? What about healthy individuals and athletes (e.g., marathon runners) who are about to engage in intense activity?
I’m not aware of any evidence that aspirin use before exercise in patients at high risk for ACS reduces that risk, but it is an interesting hypothesis. I suspect, however, that it would take a large study to show any benefit, given that event rates would probably be low.
Follow-Up:
November 7, 2014
This acute event happened 2 months ago. This patient, who decided to switch his cardiologist to the one who did the primary PCI, started a 2-week cardiac rehabilitation program at the end of September (3 weeks after the acute MI). He is now doing well on a medication regimen of aspirin 75 mg, prasugrel 10 mg, rosuvastatin 10 mg, ramipril 10 mg, and nebivolol 5 mg.
6 Responses to “Case: When an “Inappropriate” Stress Test Might Be Appropriate”
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The test is appropriate = exercise program clearance. The IMI is likely related to the exercise-induced plaque rupture, not 12 hours of beta blocker withdrawal. That someone might think this test is inappropriate, is inappropriate. Aspirin use is debatable, I would have recommended it. I’ll bet his nonHDL cholesterol was above 90 = where risk of MI starts, HRS, MD, FACC
The stress test was reasonable although case does not reveal significant details about patient and test. For discussion, I assumed he is white with estimated treated BP of 140 systolic, total cholesterol of 150 and HDL of 35 his 10 year ASCVD risk is just under 10%. Patient had not been active so I assumed he did not terminate early and reached at least 7 METS of exercise and that no imaging was performed . I certainly would have allowed him to proceed with exercise had test been performed with a longer interval after stopping acebutolol.
However my concern is stopping acebutolol and doing a stress test within 24 hours. i wouldn’t consider ETT truly unmasked unless sufficient time (2-3 days or approx 5 half-lives of chief metabolite) were allowed for the primary drug and its major metabolite to be at low levels. Generally after beta blocker withdrawal, it is recommended to advise patients not to engage in heavy physical stress for next several days. It may be that waiting until medication levels were nil would have resulted in a more revealing test.
Agreed with Silevrstein. Just to add little.
1. Acebutolol, being a cardioselective with partial agonistic activity, its sudden stoppage is less likely to lead to a massive rebound / worsening.
2. Need some more data to ascertain whether its exercise induced plaque rupture in a low risk individual (optimal lipids, sugars & SBP) or has something more.
happy diwali- festival of lights.
This case remind me the Black Swan Theory, when an event is a surprise to the observer and has a big impact, after the fact, this surprising event is rationalized by hindsight. This case is simply an affirmation of inerrente uncertainty of life and is atypical enough to not have been predicted and therefore there was no way around it. It is a good reminder that medicine is a science and an art and life carries risk.
Unfortunately, Murphy’s law seems to apply more often when the patient is a colleague.
On the other hand, he was lucky to be just at the door of an excellent hospital!