Discharging Low Risk Chest Pain: The Holy Grail

“Missed MI has the highest settlement amount of any malpractice case brought against ER physicians.” That, after where the bathrooms were, was probably the first thing I learned when I started my residency.

Chest pain is both dangerous and common with many deadly and benign causes. Thanks to public health outreach efforts more patients present to ED’s to “get checked out” when they have chest pain. Yet I often have to admit that there is no test I can send to prove their pain is not from their heart. And so, non-specific chest pain is the fourth most common diagnosis made in the ED, and yet 20% of patients who are deemed low risk are admitted. Is this because we are concerned for the patient’s well-being or our own? 

I think it’s both. The literature is full of examples of how historical, physical, EKG and laboratory testing can not reliably rule out acute coronary syndrome. Reproducible pain, relief with GI cocktails, or “atypical” character have all been shown to lack the negative predictive value necessary to reliably exclude cardiac ischemia as the cause of a patient’s pain. Cardiologists and internists love to point out how a patient lacks traditional Framingham risk factors for coronary disease.

This is fine if you are assessing someone’s 10-year risk for cardiovascular disease, but is not helpful when being applied to a patient in the ED that day complaining of chest pain. Stress test within 5 years? Normal cath in the last 10 years? Great, if you are clearing a patient for surgery who has not been complaining of pain, but useless to those of us who deal in the realm of acute care. Traditionally, the “ER miss rate” for chest pain that turns out to be from ACS is around 1.5-3%.

In an effort to reduce these numbers, and hopefully improve patient outcomes, patients are often admitted to inpatient beds, short-stay units, or chest pain units for serial enzyme testing and some provocative test to exclude ACS. Despite all these efforts, there has been no data to prove that these measures are effective in either decreasing miss rates or improving outcomes. It does, however, cause ED crowding, increases health care costs and possibly harms patients.

So what are we to do? It’s easy to explain to someone with a great story, abnormal EKG or elevated troponin why they need to stay; however, it’s much more difficult when it’s that person that you really think is probably okay but know you’ll have no leg to stand on should they have an adverse event. This March the ASPECT study was published in The Lancet. More than 3500 patients over the age of 18 with chest pain were recruited from the Asia-Pacific region. They employed an accelerated diagnostic protocol (ADP) including risk scoring using the TIMI score, ECG, and cardiac biomarkers on presentation and two hours after arrival. If a patient was TIMI 0, had no new ischemic changes on ECG and normal biomarkers according to their criteria, the patient met their criteria for low-risk for adverse cardiovascular outcomes within 30 days of their ED presentation. About 350 people (10%) met these criteria, and only 3 patients identified as low-risk had an adverse outcome which lead to a sensitivity of 99.3% [97.9-99.8%], a negative predictive value of 99.1% [97.3-99.8%] and a negative likelihood ratio of 0.1 [0.0-0.2]. These numbers look great, but look closer. The low end of the 95% confidence interval for this study’s sensitivity is 2.6%: right in the middle of our current miss rate. True the likelihood is low, but is that good enough? In my estimation, this is not a medical question. All physicians know that you can not make every diagnosis. What we are facing is the unrealistic expectations of a public that sees 67% of CPR’s survive on TV and soap opera doctors smiling at patients saying “It’s only indigestion.” Explaining Bayesian analysis and risk-benefit ratios will only induce a lethargic state in your patients suitable for intubation. It’s not that we don’t think applying these ADP’s and rapidly dispositioning patients based on them is medically appropriate, it’s whether we believe they will be palatable to the public.

I find it odd that we don’t hold pulmonary embolus to the same standard as ACS. It is also a common cause of chest pain and sudden death. Yet we confidently send people home after a negative D-Dimer, whose sensitivity ranges around 97% with a negative likelihood ratio of 0.09. Why is a 2% miss rate okay for one deadly diagnosis and not another? I think it is because juries don’t give out millions of dollars to the families of people who died from a PE. The standard of care in this case seems more like a popularity contest. If we get out in the literature, like D-Dimer, that this is a sensitive test that we can use to send people home, and everyone accepts it…we win. If the public assumes that any patient who is sent home from the ER after complaining of chest pain only to suffer a myocardial infarction within 30 days of presentation deserves a million dollars… the lawyers win.

And where in all this mess is the patient? Once we enter them in the swirling vortex of chest pain evaluation we assume everything will be okay. The downside of all of our sensitive tests lies in their low specificity, leading to excessive amounts of false positive tests. This, in turn, forces physicians to perform increasingly invasive, but more specific tests. More tests means more cost and more complications. Cardiac angiography is an amazing procedure, but retroperitoneal hematomas, contrast nephropathy, and vascular dissections are hard to explain when the procedure was performed due to breast artifact on a nuclear stress. Using similar protocols, other studies have identified low-risk profiles similar to the ASPECT study and then subjected them to either stress testing or CTA. If those tests were positive, patients underwent cardiac catheterization. In the end, no patient had an adverse cardiovascular outcome. Meaning, no testing was needed in the first place. Added to the ASPECT study, nearly 4300 patients identified as low risk using various protocols have suffered 3 adverse cardiovascular outcomes. But will this accumulating evidence change practice? Not yet. Until our society reaches a tipping point that allows physicians to practice based on their best clinical impression rather than their worst legal nightmare, low risk patients with chest pain will still be asked to undergo observation and testing that has not been shown to improve their health.

_{¹ Than M, Cullen L,Reid CM. A 2-h diagnostic protocol to assess patients with chest pain symptoms in the Asia-Pacific region (ASPECT): a prospective observational validation study. Lancet 2011; 377: 1077-84 ² Goldstein JA, Gallagher MJ, O’Neill WW. A randomized controlled trial of multi-slice coronary computed tomography for evaluation of acute chest pain. JACC 2007; 49 (8): 863-71 ³ Hollander JE, Chang AM, Shofer FS. Coronary Computed Tomographic Angiography for Rapid Discharge of Low-Risk Patients with Potential Acute Coronary Syndrome. Ann Emerg Med. 2009; 53: 295-304.}