The Low-Risk Chest Pain Conundrum: Part 1
- Nov 10th, 2014
- Jason Brown
Author: Jason Brown, Capt, USAF, MD (EM Resident Physician, University of Maryland) // Editor: Alex Koyfman, MD
Cardiovascular disease accounted for 1 in every 3 deaths in the United States in 2010; roughly 790,000 deaths total. In 2010, there were approximately 104,000,000 ED presentations by people over the age of 15 years of age. There were roughly 5,000,000 of those patients with a chief complaint of chest pain, or about 4.1%.
The challenge presented to the emergency physician by patient’s with such a deadly chief complaint is how to risk stratify them.
The care and stratification of intermediate and high-risk ACS patients are beyond the scope of this paper. We will focus on the low-risk patients, how to identify them, and then what to do with them.
Not only is chest pain a common complaint but there is significant morbidity and mortality associated with missed or delayed diagnosis of ACS. Additionally, chest pain and ACS have been cited as two of the highest risk conditions in the emergency room which resulted in malpractice claims over the last 30 years. These factors contribute to the prevalent practice of “defensive-medicine” when chest pain is the chief complaint. However, the seemingly, overly conservative management of these patients is actually based on current national guidelines.
The American Heart Association (AHA) released a position paper in 2010 which detailed how to identify those patients presenting with chest pain as low-risk using history, examination, ECG, and cardiac biomarkers.
• History: Probable ischemic symptoms in absence of any of the intermediate likelihood characteristics. Recent cocaine use
• Examination: Chest discomfort reproduced by palpation
• ECG: T-wave flattening or inversion <0.1mV in leads with dominant R waves or a normal ECG
• Cardiac Biomarkers: Normal
Patients meeting the above criteria are deemed to be low risk; meaning that they have a less than 2.5% chance of having a major cardiovascular event at 30-days. The AHA recommends that patients that meet these criteria be admitted for observation and have serial ECG and cardiac injury biomarkers obtained. If those tests become positive then the patient is admitted for further evaluation. If those tests are negative then a provocative test should be done. Unfortunately, the AHA guidelines automatically place all males and anyone with a chief complaint of chest pain/discomfort into the intermediate risk category.
The AHA did recognize that provocative testing is not universally available 24 hours a day and that outpatient testing may be appropriate for certain patients. They recommend that patients can be discharged with outpatient stress testing within 72 hours if (1) they have no further ischemic chest discomfort, (2) normal or non-diagnostic initial and follow-up ECG, and (3) normal cardiac injury biomarkers measurements.
A recent publication by Napoli sought to examine how many low-risk patients (determined by Diamond and Forrester Score) had true ACS on provocative testing. They showed no positive stress tests out of 189 low pre-test probability patients. These results call into question whether or not low-risk patients warrant immediate stress testing. More intriguing is that patients who were classified as intermediate-risk only had an ACS prevalence of 1.7%.
Recently, Louise Cullen released a paper to validate the so-called “Vancouver Chest Pain Rule.” The VCPR was employed using high-sensitivity troponins with a resultant 212 discharges. Of those 212, there were 3 cases of ACS (unstable angina with no cases of AMI (1.4%)). Using normal-sensitivity troponins resulted in 208 early discharges and 4 cases of ACS at 30 days (all 4 were unstable angina). The VCPR is shown in diagram below.
Two of the four missed cases of ACS had positive stress test with resultant angiogram showing significant stenosis. One of the four had an equivocal stress and one went directly to cath.
This data shows that patients with normal troponins and ECG at presentation and at 2-hours with low-risk ACS history can be safely discharged.
There appears to be a cohort of patients who would not benefit from an ACS work-up despite the guidelines presented by the AHA. In my next post we will further examine these clinical decisions rules both historically and prospectively.
Currently, there is ample data to show that early discharge is appropriate in up to 20% of patients presenting with chest pain. The VCPR demonstrated a 1.4% miss rate at 30-days for ACS, which is comparable to other prognostic tools which emergency medicine physicians use daily (PERC, etc).
The most important thing to remember is that your patient should be treated as an N=1. There is no amount of evidence-based medicine that can trump your clinical gestalt!!
Go AS, Mozaffarian D, Roger VL, et al. Executive summary: heart disease and stroke statistics–2014 update: a report from the American Heart Association. Circulation. 2014;129(3):399-410.
National Hospital Ambulatory Medical Care Survey: 2010 Emergency Department Summary Tables Available at: http://www.cdc.gov/nchs/data/ahcd/nhamcs_emergency/2010_ed_web_tables. Accessed September 4, 2014.
Amsterdam EA, Kirk JD, Bluemke DA, et al. Testing of low-risk patients presenting to the emergency department with chest pain: a scientific statement from the American Heart Association. Circulation 2010; 122:1756.
Napoli AM. The association between pretest probability of coronary artery disease and stress test utilization and outcomes in a chest pain observation unit. Acad Emerg Med. 2014;21(4):401-7.
Cullen L, Greenslade JH, Than M, et al. The new Vancouver Chest Pain Rule using troponin as the only biomarker: an external validation study. Am J Emerg Med. 2014;32(2):129-34.