ACS - Stress Testing

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Sensitivities/Specificities

TREADMILL: sens spec

Overall 68% 77%

ED 90% 50%


SPECT

Overall 88% 77%

ED 86% 74%


ECHO

Overall 76% 88%

ED 47% 99%

which test to use?


ETT- no baseline ST segment abnormalities (no LBBB LVH w/strain), no digoxin use, Beta blockers and CCB ok...and if a negative result will just meant the person is going to get the next test...


Def of a positive treadmill:

1) >1mm horizontal or downsloping ST segment depression or elevation at 80ms after J point

2)significant arrythmias

3)decreased systolic BP of > 10 mmHg

4) significant symptoms

a negative stress test has @ 98% negative predictive value.


does a postive stress mandate admission? not necessarily (yes at Harbor), the following are predictive of L main disease or severe multi vessel disease:

1)ST depression > 2.5mm

2)serious ventricular arrythmias

3)ST depression within 3 minutes of beginning

4)prolonged >8 minute ST segment recovery

5)hypotension >10mmHb during test or diastolic HTN >110 during test.

these either need admission or at least a discussion with a cardiologist.


Utility of past tests:

Angiography- if normal, progrssion to greater than 50% occlusion is unlikely within five years.

if <50% occlusion, about 30% progress to >50% obstruction at 3 years.

the change in chest pain and risk factors is predictive of progression (a diabetic with BS OOC not taking his/her lipid meds can accelerate much faster than your ordinary guy that does everything he should be doing...)


SPECT or EST-

<1% cardiac event rate at one year in patients with normal tests.

Bottom line:some low risk patients (10%) will have an adverse event within 31 months of initial evaluation, these are most likely the "higher risk" segment of the low risk population and therefore are quite likely to have some outpatient testing done within the next 31 months.

10 mets good 10 yr prognosis

85% max hr is adequate est


ECG Stress Testing

Protocol-

- need to reach 85- 100% maximum heart rate

- max heart rate is 220- age

- exercise capacity reported in minutes or met eq of ox consumption

- test is adequate if >6 METs reported

- test stopped when target heart rate reached

- test also stopped if BP decrease more than 10mm, sustained v- tach, st elevation >1mm, chest pain, dizziness.

- relative stop indications- st depression >2mm, arr, BP>250/115, claudication, SOB, BBB

- Positive test if horizontal or downsloping st depression >1mm for 60 - 80ms, inappr slow heart rate, decrease in BP, sust V tach, st elevation

- if positive then need angio

- if equivocal- do stress echg or nuclear scan

- no beta blockers, ca channel blockers or nitrates


Source

6/06 MISTRY