Cost Comparison of Cardiac Magnetic Resonance Imaging (MRI) Use in Emergency Department (ED) Patients With Chest Pain

Almost half of patients presenting to the Emergency Department (ED) with possible cardiac
chest pain are at intermediate risk for short term death or infarction. Most are admitted to
the hospital for serial ECG's, cardiac biomarkers, cardiology consultation, and stress
testing or coronary angiogram. However, the 2007 ACC/AHA guidelines suggest that these
patients can be managed in an observation unit (OU). Recently, cardiac magnetic resonance
imaging (CMR) has proven more accurate than traditional testing modalities for the diagnosis
of acute coronary syndrome (ACS), and has also received endorsement from the American College
of Cardiology (ACC)/American Heart Association (AHA) guidelines. Immediate application of CMR
in an OU may improve health care utilization compared to standard hospital admission for
intermediate risk patients.

Research hypotheses:

1. Patients in an OU CMR protocol will have lower cost for the index hospitalization than
standard care.

2. An OU CMR protocol for patients with intermediate risk chest pain will significantly
improve the frequency of correct cardiovascular admission decisions when compared to
standard care.

Methods summary:

110 ED patients at intermediate risk for short-term death or infarction, with nondiagnostic
Electrocardiograms (ECG) and normal initial cardiac biomarkers, will be randomized to
standard care or OU CMR protocols. Subjects in the OU CMR protocol will undergo CMR perfusion
and stress testing, followed by serial biomarkers. Standard care subjects will be admitted
for usual cardiac testing. ACS (infarction, death, coronary revascularization, unstable
angina) will be assessed by evaluation of hospital course and phone follow-up at 30 days.
Cost of hospital care will be compared among groups.

Inclusion Criteria:

- Age greater than or equal to 18 years of age at the time of enrollment

- Chest discomfort or other symptoms consistent with possible Acute Coronary Syndrome
(ACS) as indicated by the treating physician after obtaining an Electrocardiogram
(ECG) and cardiac biomarkers for the patient's evaluation

- Patient requires an inpatient evaluation for their chest pain

- The treating physician feels the patient could be discharged home if cardiac disease
was excluded

- Thrombolysis in Myocardial Infarction (TIMI) risk score ≥ 2 OR physician clinical
impression of intermediate or high likelihood that the symptoms represent ACS

- Negative pregnancy test (if sexually active, female, and of childbearing age)

Exclusion Criteria:

- Initial troponin I > 1.0 ng/ml

- New ST-segment elevation on any electrocardiogram (≥ 1 mV)

- New ST-segment depression on any electrocardiogram (≥ 2 mV)

- Unable to lie flat

- Hypotension (systolic < 90 mm Hg)

- Contra-indications to MRI(Pacemaker, defibrillator, cerebral aneurysm clips, metallic
ocular foreign body, implanted devices, claustrophobia)

- Patient refusal of medical record review and telephone follow-up at 30 days

- Terminal diagnosis with life expectancy less than 3 months

- Pregnancy per patient report or positive pregnancy test (Center for Medicare &
Medicaid Services (CMS) exclusion criteria)

- Renal insufficiency(done prior to enrollment)or end stage renal disease

- Chronic liver disease (ex. hepatitis, cirrhosis)

- History of liver, heart, or kidney transplant