Randomized Investigation of Chest Pain Diagnostic Strategies

Despite spending $12 billion annually on the emergency evaluation of chest pain in the US, only 15% of admitted patients have a cardiac cause of their presenting symptoms. Clinical decision units (CDUs) improve resource utilization and are a recommended care option by the American College of Cardiology / American Heart Association, but are underutilized in non-low risk chest pain patients due to weaknesses of traditional cardiac testing. Cardiac magnetic resonance imaging (CMR) is sensitive and specific for ischemia, can simultaneously assess cardiac function and myocardial perfusion, and could revolutionize the diagnostic process for intermediate risk patients with chest pain. The superior accuracy of CMR could decrease testing and invasive procedures. The high sensitivity for ongoing ischemia could allow imaging in parallel with cardiac markers. As a result, CMR could improve the care of emergency department (ED) patients with intermediate risk chest pain. However, the efficiency and safety of CMR has not been extensively tested in the CDU setting.

Primary Hypothesis: A CDU-CMR strategy will reduce the occurrence of the composite of revascularization, re-hospitalization, and recurrent cardiac testing at 90 days when compared to an inpatient care strategy.

Methods: Participants (n=146) at intermediate risk for acute coronary syndrome (ACS) will be recruited into a clinical trial from Wake Forest University Baptist Medical Center (WFUBMC) ED. Participants will be equally randomized to CDU-CMR or inpatient care. CDU-CMR participants will undergo resting and stress CMR imaging in parallel with serial cardiac markers. Inpatient care participants will undergo serial cardiac markers followed by existing cardiac testing as determined by their care providers. The primary outcome is the composite of 90 day revascularization, re-hospitalization, and recurrent cardiac testing. The secondary outcome is index hospitalization length of stay. Safety events include ACS after discharge, mortality, and stress testing-related adverse events.

Inclusion criteria

• Age greater than or equal to 21 years of age at the time of enrollment
• Chest discomfort or other symptoms consistent with possible ACS as indicated by the treating physician after obtaining an ECG and cardiac biomarkers for the patient's evaluation
• Thrombolysis in myocardial infarction (TIMI) risk score >/= 2 or physician impression of intermediate or high likelihood symptoms represent ACS
• Patient requires an inpatient or CDU evaluation for their chest pain
• The treating physician feels the patient could be discharged home if cardiac disease was excluded
• The treating physician feels the patient is safe for CDU care

Pretest probability assessment The assessment of intermediate risk for developing ACS will be based on a TIMI risk score >/= 2 and / or a board certified / board eligible emergency physician clinical impression of intermediate or high likelihood that the symptoms represent ACS. Physicians are encouraged to use the 2007 American College of Cardiology (ACC)/American Heart Association (AHA) guidelines as a framework for this assessment.

Exclusion criteria

• Elevated cardiac biomarkers
• New ST-segment elevation on any electrocardiogram (>/= 1 mV)
• New ST-segment depression on any electrocardiogram (>/= 2 mV)
• Known inducible cardiac ischemia without subsequent revascularization
• Unable to lie flat
• Symptomatic hypotension at the time of enrollment (systolic < 90 mm Hg)
• Contra-indications to MRI (examples: Pacemaker, defibrillator, cerebral aneurysm clips, metallic ocular foreign body, implanted devices, severe claustrophobia)
• Patient refusal or inability to comply with medical record review and follow up
• Terminal diagnosis with life expectancy less than 3 months
• Currently Pregnant
• Creatinine clearance < 45 ml/min at the time of enrollment or clinical concern for acute kidney injury
• Chronic liver disease with a creatinine clearance of <60 ml/min at the time of enrollment
• Hepato-renal syndrome
• History of liver, heart, or kidney transplant
• Confirmed angioplasty, stent placement, or coronary artery bypass grafting (CABG) within the last 6 months