ACC AHA classify patients with symptoms suggestive of ACS on arrival to emergency department, by initial evaluation of history, ECG ,and serum cardiac marker into noncardiac diagnosis, chronic stable angina, Possible ACS and definite ACS.
Patient with ST elevation and diagnosed as STEMI are treated for reperfusion therapy by PCI or thrombolytic therapy .
Those with ST and T wave changes with positive cardiac markers or hemodynamic abnormalities are admitted in coronary care unit.
For patients with possible ACS or definite ACS, without diagnostic ECG changes and negative initial serum cardiac markers can be managed in non-intensive unit. Following observation of 12 hours, If patient is positive for ischemia by ECG, serial serum cardiac marker, patient is shifted coronary care unit.
After 12 hours initial observation, no recurrent pain or negative ECG and negative serial serum cardiac markers then patient is discharged and advised stress test safely within 72 hours, to provoke ischemia. If found positive by stress test patient is shifted coronary care unit. Out patient stress test is advised in patient with low risk.
|Algorithm for Evaluation and Management of Patients Suspected of Having ACS. |
Early noninvasive testing
Found to safe, can be done within 6-12 hours, in low risk patients before discharge . Pooled data suggest that patient undergoing early TMT is CAD chances are 5% and complication secondary to TMT are negligible.
Contraindication for early TMT in emergency department
1. New or evolving ECG changes
2. Abnormal cardiac enzymes
3. Inability to perform exercise
4. Worsening symptoms
5. Clinical profile suggest that patient needs imminent coronary angiogram
Indication for TMT in emergency department
1. At least two sets cardiac enzymes four hour apart negative
2. ECG at arrival and pre TMT ECG, no abnormality
3. Absence of resting ECG changes that preclude interpretation
4. From admission to second set of cardiac enzymes report, patient asymptomatic or lessening symptoms or atypical symptoms.
5. Absence of chest pain before TMT
In patient who cannot exercise and whose resting ECG precludes interpretation, Stress echocardiography and radionuclide scans are preferred modalities.
Rest myocardial scan are more sensitive during ongoing chest pain or within two hours of chest pain, can be extended up to four hours
Stress echocardiography is sensitivity is comparable to perfusion scans i.e. 85% and specificity 95%
Myocardial contrast echocardiography with combination of Regional wall wotion abnormalities or reduced myocardial perfusion has sensitivity of 80% and specificity of 60% to 90%
Cardiac magnet resonance (CMR) for diagnosing ACS has sensitivity has 84% and specificity of 85% with addition of T2 images specificity increases to 95% without sacrificing sensitivity. Click here
CT coronary angiography is assessment of anatomy unlike other functional tests mentioned above. Negative predictive value by CT 98%, so this can be used to rule out ACS but not for diagnosing ACS.
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