Stress testing Flashcards
What are the drugs of choice for cardiac stress testing
1st: vasodilators
dipyridamole (PDE inhibitor)
or adenosine
2nd: dobutamine
Exercise stress test
Patient should reach 85% of max pulse rate (220 minus age)
Accompanied by ECG, Echo, or SPECT perfusion imaging.
When is a drug induced stress test indicated?
LBBB, post-MI, and in patients who are immobile.
When is exercise stress test indicated
To diagnose suspected CAD
In LATE-risk stratification after UA/NSTEMI has been managed, 48-72 hours after therapy.
Post PCI or thrombolytic treatment for MI to evaluate success/limitations
Stress test contraindications
Acute MI, NSTEMI or UA.
NOT USED in early/immmediate risk stratification for UA/NSTEMI.
Fever, Pericarditis or myocarditis
Symptomatic Aortic stenosis
Aortic dissection
Uncontrolled hypertension
Decompensated heart failure
Evaluations of ECG and physical exam parameters during stress test.
ECG - checking for any ST depression, elevations. 2mm ST depression is positive test.
Hemodynamic - maximum heart rate, blood pressure, any exertional DECREASE in blood pressure, or FAILURE to increase blood pressure during exercise.
Does ANGINA develop
Development of any other limiting symptoms, dyspnea.
Evaluation of ECHO stress test
Assesing EJECTION FRACTION, and Wall Motion Score Index.
> 75% hyperdynamic
55-75% normal
40-55% mild reduction
<40% intermediate reduction.
<30% Severe reduction.
Wall motion score of 2 or higher indicates high risk for future cardiac events. (scale 1-5, 3=akinetic, 4=outward bulding, 5=overt aneurysm present in diastole)
SPECT perfusion imaging evaluation
SPECT perfusion shows degree of myocardial perfusion during rest and at exercise.
Low uptake of tracer indicates poor perfusion.
Late gadolinium DTPA enhancement of infarcted myocardium – increased extravascular space in post-infarcted and scarred areas.
~90% sensitivity, ~85% specificity.
Evaluated by Summed Stress Score
Each segment is scored from 0 thru 0.5, normal to no uptake of the tracer.
Higher SSS indicates higher annual risk of ischemic event
0-3, normal
beyond 4, elevated risk
beyond 14, severe risk
