Thursday, February 4, 2016

Let’s Get Inappropriate With AHA Guidelines

How do you hide bad science?  With meta-analyses, systematic reviews, and, the granddaddy of the them all, guidelines.  Guidelines have become so twisted over the recent history of medicine the Institute of Medicine had to release a statement on how to properly create them, and a handful of folks have even gone so far as to imply guidelines have become so untrustworthy a checklist is required for evaluation in order to protect patients.

Regardless, despite this new modern era, we have yet another guideline – this time from the American Heart Association – that deviates from our dignified ideals.  This guideline is meant to rate appropriate use of advanced imaging in all patients presenting to the Emergency Department with chest pain.  This includes, for their purposes, imaging to evaluate nSTEMI/ACS, suspected PE, suspected syndromes of the aorta, and “patients for whom a leading diagnosis is problematic or not possible”.

My irritation, as you might expect, comes at the expense of ACS and “leading diagnosis is problematic or not possible”.  The guidelines weighing the pros and cons of the various options for imaging PE and the aorta are inoffensive.  However, their evaluation of chest pain has one big winner: coronary CT angiograms.  The only time this test is not appropriate in a patient with potential ACS is when the patient has a STEMI.  They provide a wide range of broad clinical scenarios to assist the dutiful reader – all of which are CCTA territory – including as every low/intermediate risk nonischemic EKG and troponin-negative syndrome, explicitly even TIMI 0 patients.

Their justification of such includes citation of the big three – ACRIN-PA, ROMICAT II, and CT-STAT – showing the excellent negative predictive value of the test.  Indeed, the issues with the test – middling specificity inflicted upon low disease prevalence, increased downstream invasive angiography and revascularization of questionable value – are basically muttered under the breath of the authors.  Such dismissive treatment of the downsides of the test are of no surprise, considering Harold Litt, of ACRIN-PA and Siemens, is part of the writing panel for the guideline.  I will, again, point you to Rita Redberg’s excellent editorial in the New England Journal of Medicine, refuting the foundation of such wanton use of CCTA in the emergency evaluation of low-risk chest pain.

The “leading diagnosis is problematic or not possible” category is just baffling.  Are we really trying to enable clinicians to be so helpless as to say, “I don’t know!  Why think when I can scan?”  The so-called “triple rule-out” is endorsed in this document for this exact scenario – so you can use a test whose characteristics for detection of each entity under consideration are just as degraded as your clinical acumen.

Fantastically, both the Society of Academic Emergency Medicine and the American College of Emergency Physicians are somehow co-signatories to this document.  How can we possibly endorse such fragrant literature?

“2015 ACR/ACC/AHA/AATS/ACEP/ ASNC/NASCI/SAEM/SCCT/SCMR/ SCPC/SNMMI/STR/STS Appropriate Utilization of Cardiovascular Imaging in Emergency Department Patients With Chest Pain”
http://www.ncbi.nlm.nih.gov/pubmed/26809772

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