Stress Test Quiz Answers

1. You admit a 65 yr old previously healthy gentleman with atypical chest pain x 1 day. EKG on admission shows sinus rhythm with occasional PVC’s and no ST abnormalities. He has three sets of CE that are neg, with a 4th set currently pending. You are placing his admission orders and want to order a stress test for the morning. The best stress method would be:




1. Pharmacologic stress with adenosine


2. Pharmacologic stress with dobutamine


3. Exercise treadmill stress test (aka GXT)


4. Stress test?! No way! Not in this high pretest probability pt. Consult cards for a cath instead


5. None of the above

The best answer is C. The best stress test method is always exercise treadmill if the patient is able to tolerate the testing (e.g. no crippling arthritis to prevent him from walking on the treadmill). The reason an exercise test is preferred is not only because it is inexpensive and readily available but that - unlike pharmacologic stress tests - it provides additional data that may be helpful to the clinician. This includes his hemodynamic response to stress and functional capacity (e.g. if his BP drops as his heart gets stressed, if he has recurrence of symptoms at a low work load, or if he can only achieve 4 METs, these are poor prognostic indicators regardless of the presence of CAD).

Pretest probability is an estimation of how likely a pt is to have CAD. Unfortunately, there is no evidenced-based scoring system. Generally, this can be determined by taking into account age, gender, and description of pain (atypical or typical) as well as other risk factors for CAD (DM, HLD, tobacco use). The pretest probability in this pt is moderate as although he is old and male (i.e. not low risk), he has atypical CP (i.e. not high risk).



2. Unfortunately, shortly after placing the order for the stress test you receive a call from the pt’s nurse. She reminds you that the ER gave your pt a dose of metoprolol before he came up to the floor. Given this new information, the best stress method would be:




1. Pharmacologic stress with adenosine


2. Pharmacologic stress with dobutamine


3. Exercise treadmill stress test (aka GXT)


4. Stress test?! No way! Not in this high pretest probability pt. Consult cards for a cath instead.


5. None of the above

The best answer is A. For the exercise treadmill test to be accurate, the patient must be able to reach 85% of their age-determined maximal heart rate (in a 65 yr old this would be 132 bpm). This is unlikely to occur in a pt taking a beta-blocker. Thus the patient will require a pharmacologic stress test. Because dobutamine works by increasing the heart’s rate and contractility, it too will be affected by beta-blockade. This leaves adenosine which works by vasodilating coronary arteries. Normal coronaries will dilate more than obstructed vessels creating “steal” phenomenon. Thus, parts of the heart supplied by normal arteries will get more blood flow.



3. Now that you have selected the type of stress test, you must next decide if you want any imaging with it and if so, which type.




1. No imaging needed


2. Echocardiography


3. Nuclear imaging (ie Myoview)


4. Stress test?! No way! Not in this high pretest probability pt. Consult cards for a cath instead


5. None of the above

The best answer is C. Any time a pharmacologic stress test is ordered, there must be some type of imaging with it. The effects of adenosine are best viewed with a nuclear study called myocardial perfusion imaging. At TCH, the nuclear agent used to view the heart is called Myoview. As adenosine dilates the coronary arteries, the parts of the heart supplied by normal arteries will get more blood flow, and this can be detected with nuclear imaging. The final order you place is for an Adenosine Myoview. Dobutamine works by essentially mimicking exercise by increasing HR and contractility and requires as cardiologist to be there to administer it. Since a cardiologist is right there, the imaging modality of choice is echo. The final order for this type of test is Dobutamine Stress Echo. Technically, either imaging modality can be ordered with an exercise stress test resulting in a final order for GXT Nuclear Study or GXT Stress Echo.

According to ACC/AHA, other indications for ordering imaging with an exercise stress test include baseline EKG changes that limit interpretation of exercise alone (LBBB, paced rhythm, ST depression at baseline that is > 1mm, or WPW), all female patients (to decrease the rate of false positives), or prior hx of revasculatization procedure such as PCI or CABG (as you want to know where ischemia is occurring). Other groups have even broader indications, including any intermediate risk patients and all patients taking digoxin (which can predispose to ST depression), so it is not surprising that essentially 100% of our patients get some form of imaging with their stress tests.



4. Amazingly, the patient was able to get his stress test today (thankfully he has been NPO!). You get a call from the heart station stating that his nuclear study showed a reversible defect. Your next decision in the management of this pt is to:
   
   
   
   1. Discharge! It is reversible after all and cardiac enzymes have been negative.
   
   
   2. Consult cards as this patient may need a cath.
   
   
   3. Medical management - start an aspirin, bblocker, ACEI and statin
   
   
   4. None of the above.
   
   The best answer is B. A reversible defect on a nuclear study means that during stress (ie when adenosine was administered or during exercise), part of the heart was not getting adequate blood flow. Since this resolves once the stress is removed (ie the adenosine wears off or exercise stopped), it is evidence of ischemia. A fixed defect is one that is present both during stress and during rest. This is a finding of previously infarcted heart. When a pt has positive findings for ischemia, the next step is to consult cardiology for a discussion of risk and benefits of cath vs medical management.
   
   
   
5. Next, during your busy night on call, you are called about a 69 yr old male with no prior history of cardiac disease but a hx of DM. He c/o substernal, crushing chest pain, worse with exertion that improves with rest. He is diaphoretic and SOB with the pain. Cardiac enzymes and EKG are pending. The best stress method would be:




1. Pharmacologic stress with adenosine and nuclear imaging using myoview.


2. Pharmacologic stress with dobutamine with echo.


3. Exercise treadmill stress test, no imaging necessary (aka GXT)


4. Stress test?! No way! Not in this high pretest probability pt. Consult cards for a cath instead.


5. None of the above.

The best answer is D. This pt has major risk factors for CAD including male gender, DM and older age, plus he has classic angina symptoms. He has a high pretest probability. In a patient such as this, you have to ask yourself, “If the stress test comes back normal, would I believe it?” When the answer is no, it is time to consult your local, friendly cardiologist and see if cath is an option.

Additionally, it is important to determine if pt is having stable angina vs ACS (unstable angina, NSTEMI, or STEMI). Thus, you would want to know enzyme and EKG results to rule out MI. It is always challenging when to say someone is having Unstable Angina because by definition they must have negative enzymes and EKG. It is truly a clinical dx (initially), but has the same pathophysiology as a MI. This patient seems to fit the picture of unstable angina, and should be treated as ACS. It is never appropriate to stress someone who is actively having an MI (or unstable angina). Other contraindications to stress testing include:



1. Sustained ventricular tachycardia, supraventricular tachycardia or severe heart block


2. Severe aortic stenosis (resulting in hemodynamic compromise)


3. Acute PE


4. Severe or symptomatic CHF


5. Acute cardiac inflammation (pericarditis, myocarditis, endocarditis)






6. Eventually, the ER calls again. This time with a 38 yr old female with h/o asthma, describing right-sided CP, sharp and stabbing in nature, nonexertional, lasting seconds before resolving spontaneously. Her only medications are advair and an albuterol rescue inhaler. The best stress method for her would be:
   
   
   
   1. Pharmacologic stress with adenosine and nuclear imaging using myoview.
   
   
   2. Pharmacologic stress with dobutamine with echo.
   
   
   3. Exercise treadmill stress test, no imaging necessary.
   
   
   4. Exercise treadmill stress test, with nuclear study.
   
   
   5. Stress test?! No way! Not in this high pretest probability pt. Consult cards for a cath instead.
   
   
   6. None of the above.
   
   The best answer is D. Women are more likely to have atypical presentations. According to ACC/AHA guidelines, a women can be considered intermediate to high risk if they are ≥ 50 yr old with any type of CP (typical or atypical) or if they are < 50 yr old with typical symptoms. In this young female with atypical CP, her pretest probability is low enough to qualify for stress testing. The best test to order is still an exercise treadmill test (GXT). However, an EKG-exercise stress test in women has both lower sensitivity and specificity. The lower sensitivity (that a negative test does not rule out disease) is due to the fact that women are more likely to have nonobstructive coronary disease or single vessel disease (i.e. harder to pick up w/ noninvasive testing). The lower specificity (that a positive result does not truly indicate disease) results in false positive tests. Women are more likely to have a false-pos ST depression, possibly due to overall lower exercise capacity than men (and Bruce protocol which ramps up quickly was designed for men). Thus, any stress test ordered in a female must have an imaging modality with it (nuclear study or echo). The presence of breast tissue can obscure the image result on nuclear studies, although this happens less with Myoview that other types of nuclear agents (such as thallium).
   
   
   
7. You discuss the planned testing with the patient but at the word “treadmill” she becomes very agitated. She informs you that there is no way she could possibly complete such testing. She has chronic low back pain and a bum knee after a car accident, you know. You agree to look into modifying the test to meet her needs. You decide that the best stress method would be:




1. Pharmacologic stress with adenosine and nuclear imaging using myoview.


2. Pharmacologic stress with dobutamine with echo.


3. Exercise treadmill stress test, no imaging necessary.


4. Exercise treadmill stress test, with nuclear imaging using Myoview.


5. Stress test?! No way! Not in this high pretest probability pt. Consult cards for a cath instead.


6. None of the above.

The best answer is B. When a pt is unable to meet the requirements for testing on an exercise treadmill test (they must be able to reach 85% of age-determined maximal HR, or 154 in a 38 yr old), then they need pharmacologic stress testing with imaging. (And, all women need imaging regardless anyway). Sure, you could stick to your original plan and make her and her bum knee try the treadmill... but when she quits after 3 min of exercise and a max HR of 108, you’ll be stuck with her an extra day while you wait for her pharmacologic stress test to get done. Just remember, that this special patient does have a h/o asthma so adenosine (which can cause bronchospasm) is contraindicated.