Acute Chest Pain Treatment and Evaluation (ACTION) Study
Acute Chest Pain Treatment and Evaluation (ACTION) Study
Objective

 1. To compare the incidence of adverse cardiac events among the patients discharged after
 evaluation through ACTION protocol with those through conventional protocol. The adverse
 cardiac events for the follow-up are defined as any of the followings:

 -  Cardiac related death

 -  Ventricular fibrillation

 -  Myocardial infarction

 -  Cardiogenic shock requiring the inta-aortic balloon pump circulatory assistance

 -  Acute pulmonary oedema requiring endo-tracheal intubation

 2. To study the sensitivity / predictive values of the various components of ACTION :12
 lead ECG ST monitoring , serial serum markers for myocardial necrosis (myoglobin, CKMB,
 TnT, graded exercise testing, stress tetrofosmin scan/ stress echocardiography) in
 predicting adverse cardiac events.

 Design -prospective randomised clinical trial

 Participants

 -patients above 25 years of age presenting to the ED with chest pain consistent with
 myocardial ischaemia but with a 12 lead ECG non-diagnostic of myocardial ischaemia .

 Intervention

 Patients were monitored continuously with a 12 lead ECG and ST segment trend monitoring and
 blood will be drawn at 0,3,6 hours after arrival at ED for serial myoglobin, creatine kinase
 MB isoenzyme (CKMB) and Troponin T (TnT) . Patients who have ECG and blood test consistent
 with myocardial necrosis were admitted to the CCU. A senior doctor in the ED reviewed
 patients who were not admitted after 6 hours of observation.

 Study Group

 A stress tetrofosmin nuclear scan was done . Patients were then admitted and discharged
 depending on the results of the stress tetrofosmin scan.

 Control group (conventional protocol)

 Patients were then be admitted or discharged at the discretion of the senior ED doctor.

 Measurement Patients were followed up at 1 week , 2 weeks , one month and six months for any
 adverse cardiac events such as cardiac related death , ventricular fibrillation , and
 myocardial infarction.

 Statistical analysis Logistic regression analysis were used to compare the proportion of
 adverse events in the two treatment groups.
Identifying the cause of chest pain is a challenge to the Emergency Physician.Coronary artery
 disease is the most common group of Emergencies that has a high potential for rapidly
 developing a lethal outcome.

 Significant proportion of patients who presented to and released from the Emergency
 Department (ED)with AMI or unstable angina develop poor outcomes. This is because a large
 proportion of AMI present atypically.The initial single 12 lead ECG done at an ED is only 50%
 sensitive for AMI.Serial ECGs have been shown to improve sensitivity by 25%.Because of these
 limitations, physicians may admit patients with chest pain, liberally. On the other hand only
 25-50 % of patients admitted to CCU without AMI are eventually determined to have Acute
 Coronary Syndrome.

 Several serum cardiac markers such as myoglobulin, CKMB and Troponin T (TnT) are found to
 increase sensitivity in detecting AMI than just history and ECG. Among them TnT is a better
 predictor of adverse cardiac event than CKMB. Absence of TnT elevation identifies a lower
 risk group of patients , but not necessarily a low risk group since TnT cannot detect
 myocardial ischaemia in the absence of myocardial injury or myocyte cell death.

 There has been some chest pain evaluation practice in the ED using the graded exercise
 testing to screen for severe ischaemia.

 Several studies have suggested the safety of exercise testing in low risk patients presenting
 to ED with chest pain.The use of exercise testing has been found to be a powerful tool for
 prognostication.

 Stress nuclear imaging was also performed at the end of 6 hours of observation instead of
 graded exercise stress testing alone. There will be a significant proportion of patients who
 will not be eligible for standard exercise treadmill stress test due to poor exercise
 tolerance. Even for those who underwent exercise testing, studies showed that 24.2% were
 inconclusive because of baseline ECG abnormalities (left ventricular hypertrophy, left
 bundle-branch block or patient on digoxin). Some patients may not be able to achieve the
 required exercise level.

 Studies have shown that the mean sensitivity and specificity for graded exercise testing to
 detect severe coronary artery disease were 68 and 77% respectively. The sensitivity of graded
 exercise test for detecting single vessel disease is lower.

 Stress nuclear imaging is valuable in establishing the prognosis of patients with a low
 likelihood of coronary artery disease. Stress nuclear scans have additive prognostic value to
 graded exercise test especially if the latter is abnormal or non-diagnostic.For those who
 cannot exercise, pharmacological stress tetrofosmin with dobutamine or adenosine will be
 performed instead.

 The efficacy of acute chest pain evaluation centre has not been compared with a conventional
 protocol in a prospective randomised clinical trial.

 Aims

 1. To compare the incidence of adverse cardiac events among patients discharged after
 evaluation through ACTION with those through conventional protocol. Adverse cardiac
 events are defined as any of the following:

 i) Cardiac related death ii) Ventricular fibrillation iii) Myocardial infarction iv)
 Cardiogenic shock requiring intra-aortic balloon pump circulatory assistance v) Acute
 pulmonary oedema requiring endotracheal intubation

 2. To study the sensitivity specificity graded exercises testing, stress tetrofosmin scan
 in predicting adverse cardiac event

 5. Treatment Plan

 First 6 hours Once informed consent was obtained, the patient was then enrolled. They were
 put on continuous ECG monitoring. Ten mls of blood were drawn at 0,3,6 hours after arrival at
 the ED for myoglobin, CKMB and TnT analysis. Blood for LDL & HDL were also drawn at 0 hour as
 well with the cardiac markers. The old hospital case record of patient, if available, were
 retrieved and previous ECG's were also compared against the new ECG.

 Patients who develop recurring chest pain consistent with myocardial ischaemia, ST segment
 elevation or depression on continuous 12 lead ECG monitoring indicating myocardial necrosis,
 or have positive CKMB (> 5), Troponin T (> 0.01), were admitted to the Department of
 Cardiology. If the patient was not admitted at the end of 6 hours, he/she were reviewed by a
 ED Registrar/Associate Consultant/Consultant. The senior ED doctor reviewed the patient, his/
 her 12 lead ECGs and blood results for serum markers for myocardial necrosis.

 After first 6 hours - Study Group (Intervention Protocol)

 The patient then underwent a stress tetrofosmin scan within 24 hours of presentation
 (exercise or pharmacological stress for those who cannot exercise). Tetrofosmin scans was be
 done at NHC or the Department of Nuclear Medicine, SGH. Patients were monitored until the
 test was completed. If the stress tetrofosmin scan turned out to be positive, the patient was
 then admitted to the hospital for further management. If the stress tetrofosmin scan was
 negative, the patient was released from ED with instructions for follow-up in the cardiology
 clinic as an outpatient.

 Control Group (conventional protocol) The patient with high or intermediate risk for coronary
 artery disease (CAD) as defined by Agency for HealthCare Policy and Research guidelines for
 Unstable Angina was admitted. The indicators for coronary artery disease are definite angina,
 T wave inversion> 1 mm in leads with dominant R waves and diabetes. If in doubt, patients
 were also admitted. Patients who were discharged from the ED will be reviewed by a
 cardiologist at the NHC cardiac clinic within two weeks.

 6. Follow Up

 Patients were followed up at one month, six months and one year for any primary or secondary
 endpoints.
Inclusion Criteria:

 -  25 years and above

 -  Chest pain suggestive of the angina

 -  12 leads ECG non-diagnostic for myocardial ischaemia or AMI

 -  diabetes mellitus

 -  family history of young AMI (less than 50 years old) There is no lower limit of age
 for those patients in the last two categories

 Exclusion Criteria:

 -  ECG diagnostic of AMI or acute myocardial ischaemia (as defined by the new Q wave , ST
 elevation or depression greater than 1mm or 0.1 millivolts in two or more contiguous
 leads)

 -  Congestive heart failure or hypotensive patients

 -  Persistent chest pain consistent with unstable angina