The Dilemma of Low Risk Chest Pain

I’m a believer that if an adult patient presents to the ED with chest pain, unless you are very, very positive the diagnosis is not cardiac, you owe it to the patient to pursue a cardiac work-up. Sounds pretty straight forward to me – but many would disagree.

I’m a believer that if an adult patient presents to the ED with chest pain, unless you are very, very positive the diagnosis is not cardiac, you owe it to the patient to pursue a cardiac work-up. Sounds pretty straight forward to me – but many would disagree.

But even when you are confident that a patient does not have a cardiac diagnosis, there are risks. The study below found that on 30-day follow-up, chest pain patients who were thought to have a clear-cut non-cardiac cause for their chest pain (whether admitted or discharged) had a surprisingly high 4% event rate (death or cardiovascular event) on 30-day follow-up. Of those with a musculoskeletal pain diagnosis, 2% died or had a cardiovascular event, 3% of the GERD diagnosis patients, 4% of the pneumonia patients, 1% of the PE patients and 12% of those with “other miscellaneous” diagnoses.

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RELATIONSHIP BETWEEN A CLEAR-CUT ALTERNATIVE NONCARDIAC DIAGNOSIS AND 30-DAY OUTCOME IN EMERGENCY DEPARTMENT PATIENTS WITH CHEST PAIN
Hollander, J.E., et al, Acad Emerg Med 14(3):210, March 2007

BACKGROUND: Algorithms for the risk stratification of ED patients with chest pain have generally focused on information to elicit a diagnosis of acute myocardial infarction (AMI) or acute coronary syndrome (ACS), and have not explored whether a clear-cut alternative non-cardiac diagnosis would allow safe discharge from the ED.

METHODS: This prospective study, from the University of Pennsylvania, evaluated the 30-day rate of a composite outcome (death, MI and revascularization) in adults presenting to the ED with chest pain possibly consistent with an ACS for whom the treating physician chose to order an EKG, but who upon completion of the ED evaluation were believed to have an alternative non-cardiac diagnosis. 

RESULTS: Of 1,996 enrolled patients (mean age 53.5, 56% female), 30% were believed to have a clear-cut alternative non- cardiac diagnosis after ED evaluation. Most of these were relatively trivial, but they did include such life-threatening problems as pulmonary embolism, aortic dissection and pneumonia. Although these 599 patients were less likely overall to experience an outcome event within the 30 days after presentation (4.0% vs. 8.8% in patients without a clear-cut non-cardiac diagnosis), the event rate was higher than the proposed very-low-risk cut-off of 1%. 

CONCLUSIONS: Although a clear-cut alternative non-cardiac diagnosis is associated with a reduced 30-day risk of cardiovascular events in ED patients with chest pain, some such patients (who include those with life- threatening non-cardiac diseases) have a bad outcome. 24 references (hollandj@uphs.upenn.edu) 

Copyright 2007 by Emergency Medical Abstracts – All Rights Reserved 6/07 – #3

And to really make your day, there’s a study indicating that 6% of ED patients with rheumatologist-confirmed costochondritis actually had an MI at the time of an ED chest pain visit (Disla, Arch Intern Med, 154:2466-9, 1994). 

I believe that most people have better things to do than go to an ED and subject themselves to waiting for protracted times with the great unwashed masses, being given a gown that doesn’t cover their tush and potentially having the ignominious privilege of being evaluated on a gurney in a hallway next to a hand-cuffed fellow trying to set a blood alcohol record. Most normal people do not want to alarm their family or friends by going to an ED and I am of the general belief that, because of these factors (and others), that patients who go to the ED with chest pain are not the same as those who go to their family doctor with chest pain – and they need to be taken very seriously. 

The study noted below, although performed in Belgium, indicated that patients who presented to a primary care physicians with chest pain were much more likely to get a GI-related diagnosis, while ED patients with chest pain were more likely to get a cardiac diagnosis.  

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CHEST PAIN IN GENERAL PRACTICE OR IN THE HOSPITAL EMERGENCY DEPARTMENT: IS IT THE SAME?
Buntinx, F., et al, Fam Pract 18(6):586, 2001 

BACKGROUND: The meaning of diagnostic test results is substantially influenced by the prior probability of disease, which may vary, in different healthcare settings, for the same complaints. 

METHODS: The authors of this Belgian study compared final diagnoses in patients with a complaint of chest pain, discomfort or tightness presenting to a general practice (GP) setting (n=320) or to an emergency department (ED) (n=580). The final diagnosis was based on hospital discharge data for the ED cohort, and on two-month follow-up information for the GP cohort. 

RESULTS: The mean age was 45 in the GP group compared with 60 in the ED group. The final diagnosis was stable/unstable angina, cardiac dysrhythmia or a serious cardiovascular disorder in 13% of the GP cohort compared with 54% of the ED group. The GP group was more likely than the ED group to have an esophageal disorder, peptic ulcer or gastritis (10% vs. 3%). The final diagnosis was a musculoskeletal condition or intercostal neuralgia in 29% of the GP cohort but only 7% of the ED cohort, and tracheitis or bronchitis in 16% vs. 3%, while serious lung disease was diagnosed in more of the ED patients (4% vs. 9%). Within the ED cohort, self-referred patients were less likely to be diagnosed with a serious cardiovascular condition; this was more common in patients referred by their physician, and most common in those arriving by ambulance. 

CONCLUSIONS: Diagnostic evaluation of patients should take into consideration substantial variation in the diagnostic case mix of patients presenting to different health-care settings. I/Q R 3/3 – J 4/4 7 references 

Copyright 2002 by Emergency Medical Abstracts – All Rights Reserved 5/02 – #2

So, given the relatively high risks, the fact that U.S. society has virtually no tolerance for missing serious conditions and missed MIs remains among the major cause of ED suits, I have a real problem with the idea that it’s acceptable to tell a patient it’s “probably not your heart.” Honestly, that’s just not good enough. At least not good enough for me, my family and probably yours.

I know, I know – people will say we can’t admit everyone with chest pain and our rate of making the diagnosis of ACS may be unacceptably low in the eyes of some, but if I were the patient, I would want a reasonable cardiac work-up. I’m well aware of the risks of false-positive tests and the idea of getting progressively more and more invasive tests associated with false-positives, but ACS is a serious diagnosis that is very hard to reliably exclude based on history, risk factors, EKGs and cardiac markers – it’s just a fact.

So what are the alternatives? The AHA has advised a very conservative approach to adult chest pain patient where ACS is being considered. Serial EKGs and ma
rkers over a period of substantial time (8-12 hours from symptom onset) and if everything is negative, some sort of stress or cardiac imaging study shortly thereafter. 

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Clearly, initiating this protocol, although likely to prevent mistakes, requires a great deal in the way of time, work and charges (substantially different from costs) and will consume a considerable amount of the patient’s time as well. Many hospitals have developed “Chest Pain Centers” just to deal with these challenges. It is clear that patients with serial negative markers and negative or nonspecific EKGs will have a low risk for having ACS – especially those under 40. However, the risk is clearly not zero and, as repeatedly brought up by Greg Henry – what is the acceptable miss rate in the United States? Is it 1%? What is it in the airline industry? If 1% of the flights had a serious malfunction, nobody would fly. What about 1 in 1,000 – still not acceptable in the airline industry – not even 1 in 1 million. 

So how can we be reasonably comfortable that a person does not have significant cardiac disease who presents with chest pain yet not spend a lot of money and time and exposing them to risks associated with more and more testing? Here are two studies – one from 2003 and one that is brand new. The newest study, which was extremely well done, suggests a two-hour protocol in low risk patients may be acceptable. It considered three factors. You had to have a TIMI score of zero with negative serial markers as specifically defined in the study (they used rapid beside point-of-care testing) and negative EKGs both initially and at two hours (as specifically defined in the study). Not that everyone has memorized what constitutes a zero TIMI score, so you need:

• Age less than 65 
• Two or fewer risk factors (FH of CAD, hypertension, hypercholesterolemia, diabetes or being a current smoke)
• No ASA within 7 days
• No history of significant coronary stenosis (> 50%)
• No severe angina (two or more anginal events in the past 24 hrs or persisting discomfort)
• No ST segment deviation of 0.05mV or more on the first EKG
• No increased troponin and/or CPK MB on the initial bloods 

The bottom line in this study – of the 9.8% of their chest pain patients who met these very low risk criteria (unfortunately a very small percentage), on 30-day follow-up, 3 of the 352 patients had a major cardiovascular event (death, cardiac arrest, emergency revascularization, cardiogenic shock, ventricular. arrhythmia or high degree AV block needing treatment or AMI). Is 3 out of 352 an acceptable miss rate – the fact is we’ll never really do better. 

A 2-H DIAGNOSTIC PROTOCOL TO ASSESS PATIENTS WITH CHEST PAIN SYMPTOMS IN THE ASIA-PACIFIC REGION (ASPECT): A PROSPECTIVE OBSERVATIONAL VALIDATION STUDY 
Than, M., et al, Lancet 377(9771):1077, March 26, 2011 

BACKGROUND: Although about 75% to 85% of patients evaluated for possible acute coronary syndrome (ACS) have an alternate final diagnosis, nearly all of those with suggestive symptoms undergo a relatively lengthy assessment. 

METHODS: This multinational observational study (14 EDs in 9 countries), coordinated in New Zealand, examined the sensitivity and specificity of a brief evaluation protocol consisting of point-of-care measurement of cardiac markers (troponin, CK-MB and myoglobin) at baseline and after two hours, determination of the TIMI risk score, and performance of an EKG for the identification of patients at low risk for a major adverse cardiac event within 30 days in patients presenting with possible ACS in the absence of ST-elevation acute myocardial infarction. A low-risk designation required a TIMI risk score of 0, absence of new ischemic changes on the EKG, and negative biomarkers. 

RESULTS: Thirty-day outcome data were available for 3,582 of 3,651 eligible patients. A major adverse cardiac event occurred within 30 days in 11.8% (most often non-ST-elevation MI). The accelerated diagnostic protocol suggested a low risk of such an event in 9.8% of the patients, and was falsely negative in three patients. The sensitivity and specificity of the protocol, including all three components, for the identification of low-risk patients were 99.3% and 11%, respectively. 

CONCLUSIONS: This two-hour diagnostic protocol appears to be a useful method of safely identifying patients with symptoms suggestive of an ACS who are at very low risk of an adverse cardiac event within 30 days of presentation. 37 references (martinthan@xtra.co.nz – no reprints) (21435709 [PMID])

Copyright 2011 by Emergency Medical Abstracts – All Rights Reserved

Here’s an older two-hour protocol. It seemed to require more physician judgment and required continuous ST segment monitoring and automated serial 12-lead EKGs (something that the vast majority of EDs don’t have – and this may be one of the major reasons this protocol never got much in the way of traction) along with nuclear stress testing. But the results were again remarkably good – in a subset that cleared all of the hurdles the sensitivity and specificity for picking up 30-day ACS was 99.1% and 87.4% — we’ll not likely to do better.

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THE ERLANGER CHEST PAIN EVALUATION PROTOCOL: A ONE-YEAR EXPERIENCE WITH SERIAL 12-LEAD ECG MONITORING, TWO-HOUR DELTA SERUM MARKER MEASUREMENTS, AND SELECTIVE NUCLEAR STRESS TESTING TO IDENTIFY AND EXCLUDE ACUTE CORONARY SYNDROMES 
Fesmire, F.M., et al, Ann Emerg Med 40(6):584, December 2003

METHODS: The authors report on the use of a chest pain evaluation protocol applied to 2,074 consecutive patients presenting with chest pain and possible acute coronary syndrome (ACS) to the Erlanger Medical Center of the University of Tennessee. Patients underwent continuous ST-segment monitoring with automated serial 12-lead ECGs and determination of CK-MB and cTnI at baseline and after two hours. Risk stratification was performed by the physician at baseline and after two hours. An increase of 1.5ng/ml or more in the CK-MB and/or 0.2ng/ml or more in the cTnI were considered to be positive. Reassessment of risk after two hours guided decisions regarding the need for immediate reperfusion therapy, admission and/or further cardiac marker testing, immediate nuclear stress testing or discharge from the ED. 

RESULTS: Risk categorization significantly improved after two hours, when categories were changed for 32% of the patients. By two hours, the sensitivity and specificity of the protocol for AMI were 93.2% and 93.9%, and the sensitivity and specificity of the entire protocol for ACS events at 30 days were 99.1% and 87.4%, respectively. The protocol missed only one patient with a life-threatening complication 27 days after presentation. In patients with a positive protocol, there was a 750-fold increase in the 30-day risk of ACS, a 102-fold increase in life-threatening complications and a 37-fold increase in the likelihood of death. 

CONCLUSIONS: This accelerated chest pain evaluation protocol reliably excluded AMI and identified the 30-day ACS risk. 47 references (FFesmire@comcast.net) 

Copyright 2003 by Emergency Medical Abstracts – All Rights Reserved 11/03 – #2 

So, seems the bottom line is that we need more research in accelerated protocols that are relatively black and white, that do not short change the patients regarding an evaluation but yet which are shown by evidence to be cost-effective and safe. Given the huge economic toll associated with low-risk chest pai
n evaluations it seems that more focused research on accelerated protocols is sorely needed and will be most welcomed.