Non-Invasive Cardiac Testing Modalities - Summary
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Non-Invasive Cardiac Testing Modalities - Summary

Exercise Tolerance Test (ETT) -> EKG or imaging (TTE, SPECT)

 • ETT preferred over pharmacologic testing if pt is able to reach goal exertion

 • Additional information obtained during ETT: exercise duration, METs, BP/HR response, HR recovery, double product (HR x SBP), Duke Treadmill Score (estimates risk of CHD in patients w/chest pain undergoing treadmill stress testing)

     o Duke Treadmill Score = Exercise time (minutes based on the Bruce protocol) - (5 x maximum ST segment deviation in mm) - (4 x exercise angina [0 = none; 1 = nonlimiting; 2 = exercise limiting]) 

Pharmacologic Stress Test -> imaging only (TTE, SPECT, PET, MRI)

a) Adenosine/Regadenoson

 • Detects ischemia by coronary steal (vasodilation via cAMP)based on the principle that stenosed coronary arteries are unable to further dilate to adenosine and therefore have limited flow reserve to areas distal to the stenosis, producing a relative perfusion deficit

b) Dobutamine

 • Workload induced by positive inotropy and chronotropy via beta-1 receptor agonism

 • May cause tachyarrhythmias: Caution with MI<48h, hx of malignant arrhythmia, severe AS, HOCM, severe HTN, severe PAH

Cardiac CTA (CCTA)

 • Screening: CCTA should NOT be used to screen asymptomatic patients

 • Low Risk: CT has a high NPV (99%) in low-risk patients for CAD rule-out

 • Moderate Risk: CCTA is reasonable for further risk stratification in patients at “intermediate” risk of CAD or patients with equivocal

stress test results

Coronary MRI (cMRI)

 • CCTA has higher Sn/Sp (85%/95%) than cMRI (72%/87%) for coronary stenosis (>50%) 

 • cMRI is preferred for post-CABG vessel imaging  Sn/Sp 96%/92% for >70% graft stenosis.

 • cMRI is also preferred for evaluation of suspected or known congenital or acquired coronary anomalies

 • cMRI w/ stress detects significant stenosis (>50%) with Sn/Sp 83%/83% greater than stress echo 

Viability Testing

 • Utility: to determine the viability of ischemic myocardial tissue -> “hibernating myocardium”

 • Imaging Modalities: SPECT (thallium or sestamibi), PET, TTE, MRI

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