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E-case D-1: December 9-13, 2002

Melissa Chen, R-3

A 55 year old woman with hypertension and diabetes comes to your clinic with a 3 month history of right sided chest discomfort with climbing 3 flights of stairs. Her EKG shows signs of LVH with strain. How should this person be evaluated?

When you suspect coronary artery disease, functional stress testing can aid you in making the diagnosis as well as determining functional capacity and risk of having an adverse cardiac event. See table below for a summary of the advantages and disadvantages of each test.

If possible, try to choose exercise over pharmacologic stress, because that will give you a functional assessment of the patient's symptoms. In general, the AHA guidelines tell us to choose exercise EKG for patients with a normal resting EKG and no known CAD. It is recommended to add imaging for resting EKG abnormalities or known CAD. Exercise treadmills in women are less specific (i.e. there are more false positive tests) but still remain the test of first choice. The type of pharmacologic stress is chosen by presence of reactive airway disease and morbid obesity. If RAD, choose dobutamine over persantine/adenosine. If the patient weights over 230#, choose adenosine over persantine.

In the case of this woman, because she has resting EKG abnormalities that would make the stress EKG difficult to interpret, an exercise-imaging test is the best option.

Type of Test	General info	Advantages	Contraindications/Disadvantages
Exercise stress	Stop beta blockers 1-2d prior (unless assessing efficacy of beta blockade). NPO x3h.	Assessment of functional capacity	Unstable angina, severe aortic stenosis, SBP>180, severe exercise limitations, preexcitation, resting EKG ST-T changes or LBBB.
Exercise Treadmill (EKG)	Can also use bike or arm ergometer.	Cheap	Less specific in women, and lower sensitivity in general; not as useful if there are resting EKG abnormalities. History of revascularization [1]
Exercise Echo		Valvular heart disease; cheaper than nuclear medicine.	Subjective interpretation; difficult when resting wall motion abnormalities exist; can't calculate prognosis because of limited data; poor image quality in many (obesity)
Exercise Nuclear Med study		Can assess EF/LV size/ extent of CAD/myocardial viability	Increased cost, may have artifact from soft tissue
Pharmacologic stress	NPO x 6h. (can get false positive isotope uptake in stomach)	Useful in pts with musculoskeletal limitations; more accurate if LBBB	Can't assess functional capacity
Persantine (dipyridamole) Nuc Med study	Hold theophylline x 72hrs prior, caffeine x 12 hrs	Standard pharmacologic nuclear med scan.	Bronchospasm, oral dipyridamole therapy, high-grade heart block, SSS, hypotension, wt >230#.
Adenosine Nuc Med study	Hold theophylline x 72hrs prior, caffeine x 12 hrs	Shorter half-life than persantine. Better for weight >230lbs.	Bronchospasm, oral dipyridamole therapy, high grade heart block, SSS, hypotension
Dobutamine Echo	No beta blockers x 24-48hrs.	Valvular heart disease	HOCM (IHSS), dissection, severe HTN, arrhythmias, obesity (compromises echo image)

What do we have available at PacMed?

Nuclear Medicine studies get referred to Swedish. Treadmills and regular echos go to First Hill Cardiology for now. Stress echos go to Minor and James. The nuclear medicine folks usually decide which nuclear isotope to use; the two options are thallium and sestamibi.

References:

Lee Thomas and Charles Boucher. "Noninvasive tests in patients with stable coronary artery disease." NEJM 344 (24): 14 June 2001, 1840-1844.

Weiner, Donald A. "Advantages and limitations of different stress testing modalities." UpToDate March 2002.

[1] In patients with angina and a history of revascularization, characterizing the ischemia, establishing the functional effect of lesions, and determining myocardial viability are important considerations.