First-class training from first-class emergency medicine physicians
The Chest Pain Evaluation Unit ("CPEU") was initiated in 1993 as a joint program of the Department of Emergency Medicine and the Division of Cardiovascular Medicine with the support of the UC Davis Heart Center. Its development was stimulated by the tradition of admitting large numbers of low risk patients with chest pain to Coronary Care Units ("CCU") to "rule out" myocardial infarction. This practice, which is virtually universal, has resulted in a diagnosis of acute myocardial infarction in as few as 15-20% of patients admitted to CCUs, an inefficient strategy in clinical and economic terms.
Close cooperation between the two departments has been an essential feature of the CPEU, which is administered by the Department of Emergency Medicine with close consultation by the Division of Cardiovascular Medicine. The director is J. Douglas Kirk, M.D., professor of emergency medicine and the associate directors are Sam Turnipseed, M.D., professor of emergency medicine and Ezra A. Amsterdam, M.D., professor of cardiovascular medicine.
Goals of the CPEU:
The CPEU is an integral part of the emergency department process of patient management but focuses on non-critical patients, thereby allowing emergent cardiac patients to receive a concentrated, fast-track approach from emergency department physicians dedicated to these patients. The CPEU is staffed by three physicians who have completed residency in internal medicine with further training in exercise treadmill testing. The CPEU is covered daily by one of these physicians who is dedicated to this service. Consultation is available to these physicians at all times by the CCU attending cardiologist in selected cases as needed. During off hours, these patients are managed by the Cardiology Inpatient Service (CIS), which can admit them to the CPEU for further evaluation and disposition the following morning by the CPEU attending physician.
Immediate excercise treadmill testing
Patients presenting to the emergency department with chest pain suspicious of an acute coronary syndrome (ACS) who are identified as low risk by clinical criteria (< 7 % MI, < 15% unstable angina) for an ischemic event and its complications are triaged to the CPEU. If low risk is confirmed (clinically stable and resting ECG being normal or having only minor nonspecific repolarization abnormalities) and other serious causes of chest pain are absent on screening evaluation, the patient usually undergoes immediate exercise treadmill testing (IETT) performed by the CPEU physician with support from the cardiology technical staff.
A unique aspect of our application of this approach at UC Davis Medical Center to our knowledge is, performance of IETT without prior measurement of cardiac serum enzymes in these carefully selected and screened patients, a method developed in our early experience and validated by absence of any adverse effects in over 1,200 IETTs since the initiation of the CPEU. Patients with positive IETTs are admitted for further evaluation and those with negative tests are discharged from the emergency department.
The majority of patients with nondiagnostic tests are discharged from the emergency department with referral for outpatient management. Our results have demonstrated that only 13% of these patients have positive IETTs (with 40% of these false positives). With this approach, nearly 90% of patients previously identified as requiring admission to exclude an ACS, can be safely discharged. This strategy has provided a safe, efficient and cost-effective method of stratifying this patient population into those requiring admission and those who can be discharged and managed as outpatients. This program improves utilization of telemetry beds, affords vital cost savings and maintains sound patient care.
As anticipated, this experience with IETT has been an area of active clinical research. This area of further cooperation between emergency medicine and cardiology has resulted in presentations at national meetings and in scientific papers 1-9 and is an important area of growth in the CPEU.
Cardiac short stay unit (CSSU)
Low-risk patients in whom IETT is not applicable (e.g., inability to exercise; repolarization abnormalities in the resting ECG; moderate suspicion for ischemic event) are admitted for monitoring to the CSSU where they are managed by the CPEU physician. Depending on the individual patient's presentation, one of a number of approaches can be implemented, including an accelerated "Rule Out" myocardial infarction protocol, noninvasive cardiac stress imaging (i.e., stress echocardiography or scintigraphy) or direct referral for coronary angiography. Patient disposition is usually accomplished on this service within 24 hours, with a majority discharged home and those diagnosed with an ACS admitted to the CIS.
Conclusions and future directions
The CPEU has been a model for demonstrating the advantages of an integrated effort between two disciplines with overlapping interest in this low risk, but challenging, patient population. The joint expertise of emergency medicine and cardiology has provided a departure from the traditional, inefficient and costly approach to these patients. It has also been a source of active clinical research which has attracted regional and national interest. An important aspect has been its singular contribution to resident and fellow training. Future plans include the availability of immediate stress echocardiography and resting myocardial scintigraphy in the emergency department for low risk patients in whom IETT is not applicable, as indicated above. Expansion of the patients evaluated by the CPEU is underway and includes syncope (already initiated), mild congestive heart failure, uncomplicated supraventricular arrhythmias and selected patients with a history of prior coronary artery disease (already initiated).
- Amsterdam EA, Kirk JD, Turnipseed SD, Diercks DB, Lewis WR. Exercise Testing of Low Risk Patients Presenting with Acute Chest Pain: Rationale, Methods, Results. Exercise Testing: Current Concepts and Recent Advances. Kluwer, Norwell, MA. 2001.
- Amsterdam, EA, Kirk JD, Diercks DB, Lewis WR, Turnipseed SD. Immediate Exercise Testing for Assessment of Clinical Risk in Patients Presenting to the Emergency Department with Chest Pain: Results in 1,000 patients. Journal of the American College of Cardiology 2002; 40:251-6.
- Amsterdam, EA, Lewis WR, Kirk JD, Diercks DB, Turnipseed SD. Acute Ischemic Syndromes: Chest Pain Center Concept. Cardiology Clinics 2001:20(1):117-136.
- Kirk JD, Turnipseed SD, Diercks DB, London D, Amsterdam EA. Interpretation of Immediate Exercise Treadmill Test: Interreader Reliability Between Cardiologist and Noncardiologist in a Chest Pain Evaluation Unit. Annals of Emergency Medicine, July 2000;36:10-14.
- Kirk JD, Diercks DB, Turnipseed SC, Amsterdam EA. Evaluation of Chest Pain Suspicious for Acute Coronary Syndrome: Use of an Accelerated Diagnostic Protocol in a Chest Pain Evaluation Unit. American Journal of Cardiology 2000;85:40B-48B
- Lewis WR, Amsterdam EA, Turnipseed SD, Kirk JD. Immediate Exercise Testing of Low Risk Patients with Known Coronary Artery Disease Presenting to the Emergency Department with Chest Pain. Journal of the American College of Cardiology June 1999;33(7):1843-1847.
- Kirk JD, Turnipseed S, Lewis WR, and Amsterdam EA. Evaluation of Chest Pain in Low Risk Patients Presenting to the Emergency Department: the Role of Immediate Exercise Testing. Annals of Emergency Medicine 1998;32:1-7.
- Lewis WR, Amsterdam EA. Evaluation of the Patient with "Rule out Myocardial Infarction". Archives of Internal Medicine 1996;156:41-45.
- Amsterdam EA, Lewis WR, Kirk D, and Turnipseed S. New Approaches to Management of the "Rule out MI" Patient. Clinician 1995;13:33-38.
- Lewis WR and Amsterdam EA. Safety and Utility of Immediate Exercise Testing of Low Risk Patients Admitted to the Hospital for Suspected Myocardial Infarction. American Journal of Cardiology 1994;74:987-990.
- Kost G., Kirk JD., Omand K. A Concensus Strategy for the Use of Cardiac Injury Markers (Troponin I & T, Ck-mb Mass and Isoforms, and Myoglobin) in the Diagnosis of Acute Myocardial Infarction. Archives of Pathology & Laboratory Medicine 1998;122:245-251.
Immediate Exercise Treadmill Test Protocol
- All patients with chest pain suspicious of an Acute Coronary Syndrome whom admission for R/O MI is advised and no other etiology for chest pain is considered or found (e.g., Pulmonary Embolism, Aortic Dissection, Esophageal Rupture, etc.)
- Patients must be clinically stable and without evidence of LV dysfunction.
- ECG must be normal or have only minimal nonspecific repolarization abnormalities.
- Inability to complete a symptom limited exercise treadmill test
- ECG abnormalities precluding accurate interpretation (e.g. Bundle Branch Block, LVH with strain or Digitalis Effect).
Emergency Department Evaluation
- Physical examination not suggestive of LV dysfunction or significant valvular disease
- Equal arm blood pressures
- Chest X-ray not suggestive of Aortic Dissection or Congestive Heart Failure
- CBC and Chem- 7 only if anemia and/or abnormal K+ suspected
Modified Bruce Protocol.
Test Endpoints are:
- Symptom limited
- Fall in systolic blood pressure > 10mmHg
- Coupling of ventricular ectopics
- Sustained SVT
- 1mm ST segment depression (horizontal or downsloping) or elevation 80 msec after the J point.
- Criteria for a positive test are the aforementioned ST segment changes.
Accelerated Rule Out MI
- Continuous Telemetry Monitoring
- ECG's @ 0, 3, 6hrs and prn Chest Pain
- Myoglobin @ 0, 3, 6, ± 12 hrs