CAD Flashcards
absolute contraindications for ETT
AMI High risk unstable Angina Uncontrolled CHF Uncontrolled Arrhythmia Severe AS - Symptomatic Myocarditis/Pericarditis Aortic dissection Pulmonary embolus
Relative contraindications of ETT
Left main CAD Moderately stenotic valvular heart dz HOCM Electrolyte abnormalities HTN > 200/100mmHg Tachy/bradyarrhythmia High degree AV block
Indication to stop ETT
patients desire to stop moderate angina CNS symptoms ST elevation >/= 1mm BP drop of >/= 10mmHg from baseline Serious arrhythmias
some labs stop exercise once ST depression reaches 2.0mm
Risk of death or MI associated with ETT
1 in 2500 tests
Most serious contraindications for ETT that can be easily overlooked in the setting of chest pain
Aortic dissection
Pulmonary embolus
represents an ischemic response on ETT
> /= 1mm horizontal or downsloping ST depression measured 60 to 80msec after the J point
Issue with up-sloping ST depression in setting of ETT
up-sloping ST depression increase sensitivity for the test but at the expense of an unacceptable decrease in specificity.
True or false. ST depression that develops in the recovery phase has the same diagnostic accuracy as depressions during exercise
True
The most common site for ST changes during ETT
> 90% of positive responses occur in leads V4 - V6 regardless of the site of anatomical CAD.
ST depressions in confined to these leads likely represents a false positive finding
ST depressions confined to the inferior leads alone usually represents a false positive finding.
Unlike ST depression ST elevation during ETT provides this benefit..
STE during ETT can localize the site of ischemia and usually reflects high grade stenosis.
Calculate sensitivity
TP/TP+FN
Calculate specificity
TN/TN+FP
PPV
TP/TP+FP
NPV
TN/TN+FN
Calculate the overall accuracy of a test
TN/All tests
not very accurate due to verification bias (aka referral bias) only patients with positive test get referred for procedure.
If very few patients with a negative test a referred for the procedure the sensitivity gets closer to 100% & specificity closer to 0%
what is the sensitivity and specificity of an ETT
Sensitivity - 68%
Specificity - 77 %
the above was derived by meta-analysis
a study performed here the cath all patients regardless of ETT result reported a sensitivity of 45% and specificity of 68%
the major impact of verification bias is the artifactual increase in the test sensitivity and decrease in its specificity.
In the interpretation of the ECG during ETT in pt with a RBBB what modification is necessary?
ignore V1 - V3, interpretation is confined to the left precordial leads (v4 - v6)
The factors decrease the sensitivity of an ETT
beta blocker
Factors that reduce test specificity of ETT
presence of LVH
ST/T wave changes at baseline
Digoxin use
The strongest prognostic ETT variable
Exercise duration
calculating the bruce score
exercise capacity (time in minutes) - 5x Magnitude of ST deflection (in mm) - 4x angian index (0 = none, 1=non limiting, 2= limiting)
Duke treadmill score low, intermediate, high
low >/= 5 ( 0.3)
intermediate -10 to +4 (1.3)
High < -10 (5.0)
Annual CV mortality in parenthesis
common application of cardiopulmonary exercise testing
- Identification of underlying cardiac and pulmonary disease in a patient with unexplained dyspnea and prognostic assessment.
- assessment of candidacy for cardiac transplantation in a patient with congestive heart failure.
what are the 3 groups of patients whom guideline recommends addition of an imaging modality to stress testing?
- an inability to exercise with requirement of pharmacologic stress
- Significant abnormalities on the resting ECG that preclude interpretation of the stress ECG
- High pretest probability of CAD
Indication for coronary artery calcium scoring?
used for further refinement of cardiovascular risk assessment in asymptomatic individual categorized as intermediate risk on the basis of medical variables.
These factors decrease the sensitivity of a stress echo
- delay in obtaining images > 90s
- single vessel dz (smaller ischemic territory)
- shorter exercise duration in which ischemic threshold is not met.
- Poor endocardial visualization (improved with echo contrast)
Calculate LV Mass
LV Mass = 0.8 x 1.4[(IVS+LVID+PWT)^3 - LVID^3] + 0.6g
At what 10 year ASCVD risk level is statin recommended in diabetic patients
Statins are recommended for primary prevention in all diabetic patients regardless of ASCVD risk.
High intensity Statins are indicated for ASCVD risk > 7.5%
what are the 4 phases of valsalva in a normal patient
Phase 1. Increase aortic pressure due to increased intra-thoracic pressure
Phase 2. Decline in Pressure due to decreased pre-load. subsequent increase in HR due to baroreceptor response
Phase 3. with release of Valsalva, the aortic pressure declines further in response to decrease in intrathoracic pressure.
Phase 4. recovery period with increase in LV preload, aortic pressure, and pulse pressure.
Response to valsalva in a patient with Heart failure
Square wave response.
Pt may have an absent overshoot of phase 4
The absent overshoot pattern indicates decreased systolic function and the square-wave response indicates elevated filling pressures.
Half life of thallium
73.1 hrs
half life of ammonia-13
10 minutes
half life of rubidium
75 secs
