Written by: Henry Higgins, MD
John Dayton, MD, FACEP, FAAEM
The methods used to detect significant coronary artery stenosis/disease have been evolving alongside technological advances for many years. A variety of detection strategies have been used in emergency medicine for the detection of CAD and prevention of acute myocardial infarction. Risk assessment, ECG, cardiac enzyme markers, and lipid panels are among some of the standard modalities used by emergency medicine physicians when evaluating patients for potential CAD. The use of Coronary Artery Calcification scoring (CAC Scoring) and Coronary CT Angiography (CCTA) are both relatively new modalities being investigated as tools by some physicians to evaluate patients for CAD. Freestanding Emergency Centers (aka Standalone ERs, Satellite Emergency Centers, FSEDs, FECs) are a relatively new setting to practice emergency medicine and are becoming more prevalent. These fully functional emergency departments (that are not physically attached to hospitals) are sometimes locally owned and operated by physicians. These physician-owned facilities are not only physically unattached but also politically unattached from hospitals. The freedom from hospital politics allows the physician- owned and operated FECs to quickly adopt the use of new technologies like the CAC and CCTA. This case report demonstrates the use of both CAC and CCTA in two patients who were treated in a physician owned and operated Free-Standing Emergency Center in greater Austin, Texas.
Nearly 6 million individuals are evaluated each year for acute chest pain in the emergency department1. Despite standardized protocols and high vigilance, between 2% and 6% of patients are erroneously discharged with missed myocardial infarction2. Proponents of CCTA advocate its potential usefulness in this patient subgroup, highlighting the high negative predictive value (NPV) of CCTA, allowing the physician to successfully identify individuals in whom no obstructive CAD exists and who have a favorable prognosis.
A single-center, randomized study of 197 individuals presenting with acute chest pain to the emergency department compared a CCTA-based diagnostic evaluation strategy with standard-of- care algorithms that used myocardial perfusion scintigraphy (MPS)3 with single photon CT. In contrast to individuals undergoing standard-of-care assessment, individuals undergoing CCTA experienced reduced diagnostic time in the emergency department (3.4 and 15.0 h, respectively; p value 0.01) and fewer repeat evaluations for chest pain. These findings translated to lower costs for a CCTA-based evaluation by almost $300 per patient. In 6-month and 2-year follow-up, no adverse CAD events occurred in discharged individuals by either a CCTA- or standard-of-care– based evaluation (G. Raff, personal communication, June 2009).
Based upon other researchers findings it become standard practice to utilize CCTA in the emergency department setting. If the CCTA use appears to be acceptable in a hospital based emergency department then it should be equally acceptable and advantageous in a FEC. With the lack of on-hand cardiology consultants in the setting of the FEC, one could argue that the use of CCTA may be a very prudent choice in specific patients whose CAD status may not be clearly defined. The CCTA results in the FEC setting could greatly impact the treating emergency physician’s confidence when deciding whether to transfer a patient to a hospital for cardiology consultation or to send the patient home for further outpatient work up.
At 13:10 a 53 year-old male patient was brought to the emergency department immediately after developing fatigue and chest pressure, dyspnea, nausea and vomiting, diarrhea which ultimately resulted in the patient collapsing. He had been working on an outside sprinkler on a Saturday afternoon in the 90 degree weather of greater Austin, and he suffered this episode while standing up after using the restroom. As a result of his collapse he also suffered a small laceration above his right eye which was easily re-approximated with adhesive glue. His syncopal episode had lasted for less than 60 seconds. He had eaten a large breakfast and consumed several cups of coffee before the incident. Upon presentation to the FEC, most of his symptoms had completely abated. He only admitted to feeling fatigued with mild headache at triage. He denied any active chest pain or shortness of breath. He denied any active chest pressure or numbness. He indicated that the only reason that he came was that his family forced him to get “checked out”.
He had never suffered any episodes like this before, but he also had neglected to undergo routine health maintenance and had not seen a doctor for several years. He never used tobacco and did admit to drinking a small amount of alcohol once every few months. In the past he had been on medication for hypercholesteremia (simvastatin) and had been treated for very occasional anxiety reactions. He had never had surgery or undergone a cardiac stress test.
His family history was remarkable for having a father who was diagnosed with CAD in his 50’s. His initial EKG, CXR and blood work were unremarkable (see figure). His vital signs were all within normal range and his orthostatic tilt test was negative. He was given 1000cc IV fluid crystalloids with near resolve of his fatigue symptoms. The attending physician then diagnosed him with “heat stroke with dehydration, face laceration, and syncope”.
In further discussion with this now very talkative patient, his CAD risk was further evaluated and was felt to possibly have contributed to his syncope. Per the family, this patient is notorious for minimizing his symptoms and avoiding care. After discussion with this patient, it was decided that he undergo a CAC score in the FEC as part of his cardiac screening.
The lab result showed an elevated D-Dimer of 910 (nml range 0-399), an elevated WBC of 17.7 and glucose of 125. His other laboratory tests, including troponin, were all found to be within normal limits. The patient’s CAC CAC was found to be 465, which can represent extensive CAD. Based upon these results, the emergency physician obtained a “triple rule out” CT study which utilizes a gated helical cardiac CT to evaluate both the lungs and the heart for the presence of coronary artery disease (CAD via CCTA), pulmonary embolus (PE via CTA), and aortic pathology all in one study.
Coronary Artery Calcification CT Results
His calcium score (CAC) was 465.
Coronary CT Angiography
CCTA performed in the FEC demonstrated that multiple vessels had stenosis: There was a 50% stenosis of the right coronary artery and 70-80% stenosis, with soft tissue plaque formation and calcifications, involving the distal left main coronary artery near the bifurcation at the level of the left anterior descending artery as well as the circumflex coronary artery. Narrowing of the left anterior descending coronary artery was also noted. Soft tissue plaque formation with narrowing was also seen involving the obtuse marginal branches.
With this information, Cardiology & CT surgery were then consulted by phone to set up timely follow up and he was sent home from the freestanding ER. He was informed of his high risk of heart attack and he agreed to follow up immediately with any symptoms while awaiting his Cardiologist and CT Surgery outpatient follow up visits. He underwent 3 vessel CABG 14 days later.
On follow up, the patient states that he feels much better now after having CABG surgery and that he had not realized how poorly he felt for the several months prior to coming to the FEC. He indicated that he is far more active than he has been for years.
This case demonstrates how the CCTA may be useful in screening high risk patients in both the traditional emergency department and FEC. It also demonstrates how some patients with normal traditional test results (cardiac enzymes, ECG, Chest X-rays) may still harbor high grade coronary artery disease. This active 53 year-old man was found to have significant disease that may have led to a myocardial infarction within the next few years. This patient was also likely to have not seen another doctor until he was having an active myocardial infarction. The “widow maker” lesion that this man had developed may not have allowed him to survive long enough to get to the emergency department when that eventual myocardial infarction occurred.
This case demonstrates the importance of having emergency physicians also focusing on screening their patients for disease. Too often we are occupied with ruling out active myocardial damage. It is also important to evaluate risk factors and discuss the patient’s health screening activities. Having the capability to offer CCTA in the ED may have saved this man’s life and most certainly helped prevent him from having a myocardial infarction.
1 McCaig LF, Burt CW. National Hospital Ambulatory Medical Care Survey 2003. Emergency Department Summary: Advance Data from Vital and Health Statistics, No. 358. Hyattsville, MD: National Center for Health Statistics, 2005.
2 Pope JH, Aufderheide TP, Ruthazer R, et al. Missed diagnoses of acute cardiac ischemia in the emergency department. N Engl J Med 2000;342:1163–70.
3 The Present State of Coronary Computed Tomography Angiography A Process in Evolution James K. Min, MD, Leslee J. Shaw, PHD, Daniel S. Berman, MD. JACC Vol. 55, No. 10, 2010 March 9, 2010:957–65