Chasing Chest Pains - Risk Stratification and Non Specific Troponinemia

Chest pain is caused by a myriad of causes ranging from benign to life threatening, some of which can cause death within minutes or hours. While evaluating chest pain, ACS is always high up on our list of differential diagnosis and as Emergency Physicians, it is our responsibility to not only robustly identify ACS and but also avoid needless investigations and unnecessary admissions for those who can be safely discharged from the ED after risk stratification.

Here is an overview of ACS with breakdown of terminologies, key points about history/physical exam and biomarkers and specifics about what to do with a low risk ACS patient:

Classical ACS presents with:

•             Heavy, aching or tight
•             Central chest or left sided
•             Not related to respiration or movement
•             May radiate to arms, neck, or jaw

You will often see patients who have one or a few of these features but end up having a completely negative work up for ACS. Remember, the history is helpful only to risk stratify – not to confirm your diagnosis. Everyone perceives pain in a different way but history is the first step during evaluation and risk stratification. 

Atypical ACS

Atypical presentations of ACS are common, occurring in up to 1/3rd of patients, mostly in the elderly, diabetics and women. Advanced age, co-morbid factors, delay in diagnosis lead to the increased mortality in these populations.

Things you must ask/look for:

• Radiation to both arms – Likely  ACS
• Radiation to left arm – Likely ACS
• Nausea / Vomiting – Likely ACS
• SOB on exertion – Likely ACS
• Associated with Sweating – Likely ACS
• Hypotension – Likely ACS
• S3 – Likely ACS
• Describes as previous angina - Likely ACS

• Pleuritic/ Positional/ Sharp Pain – Unlikely ACS (not impossible)
• Tender on Palpation – Unlikely ACS (not impossible)

A good history helps in risk stratification. Don’t rule out ACS just based on the history alone. With the slightest of concern, get an ECG.

Risk Factors

Risk factors once again help us to risk stratify but just based on the absence of risk factors you cannot rule out ACS. Get worried if the history is concerning even if there are no risk factors at all. The next step is ECG.

And what if the history is concerning but ECG is normal?

An ECG showing ST depressions, TWI or STE is obviously concerning. Patients who present with chest pain with suspected cardiac ischemia based on the history but normal ECG should still undergo further diagnostic testing with cardiac markers before they can be confidently assigned to a low risk group.

What if the history is concerning with ongoing ischemic symptoms, but ECG is normal and troponin is not elevated?

This sounds very much like Unstable Angina. DO NOT SEND ANYONE HOME WITH CONCERNING AND PERSISTING SYMPTOMS DESPITE NEGATIVE TROPONINS.

Unstable Angina can occur when you are resting, sleeping, or during  little physical exertion. The pain may last longer than stable angina and rest or anti-ischemic medications usually do not help relieve it. USA can have an ischemic or normal ECG but should always have negative troponins by definition.

In contrast, Stable Angina is very predictable with Chest Pain on exertion that gets better on resting. Stable Angina us also relieved with anti-ischemic medications.

Beware of the Non-Specific Troponinemia AKA Troponinitis!

Troponins are the preferred and recommended markers of myocardial necrosis. Read more about troponins here. But the new generation hs troponins are extremely sensitive and thus less specific i.e you might end up getting a false positive elevated troponin leading to unnecessary admissions and work ups.  So if history is not suggestive of ACS but troponin is elevated – get a few more ECGs but do think of other possible causes of an elevated troponin such as:

With hs Troponins, we are now able to pick up even the minimal level of troponins in a patient’s system and thus those who were diagnosed as Unstable Anginas (Ischemic Chest Pain/ECG but normal troponin levels) a decade back are now labeled as NSTEMIs (Ischemic Chest Pain/ECG but a raised troponin). At this moment, although it is controversial but some experts do believe that Unstable Angina does not even exist anymore in this era of highly sensitive troponins.

ACS includes STEMI, NSTEMI, USA (not stable angina)

Patients with STEMI do not require troponin since their initial treatment is determined by their clinical presentation and ECG findings. Patients with STEMI are identified quickly, assigned a high risk category and have a well-defined treatment strategy (ie. urgent reperfusion with PCI or thrombolytics).

When does NSTEMI need immediate cathlab:

The ACC/AHA guidelines for NSTEMI recommend < 2 hour cath for:

1. Refractory ischemia
2. Ischemia with hemodynamic or electrical instability

If you are worried about a patient, get serial ECGs, send troponins and involve cardiology at the earliest.

Disposition of a Low Risk Patient – Slightly concerning history but non-ischemic ECG and negative enzymes. 

Here we are specifically talking about Unstable Anginas which can be further divided into two groups i.e negative troponin with ischemic ECG and negative troponin with a non-ischemic ECG. 

Current data shows that if patients have negative troponins with non-ischemic ECG, then prognosis is not bad even if they are diagnosed with unstable angina.  If they have unstable angina with an ischemic EKG, then they have a worse prognosis.

Note - if you see an Ischemic ECG – Get worried even when if the enzymes are normal

Low risk unstable angina with negative troponins can have:

Shared Medical Decision Making -  Do serial troponins and serial ECGs. Current evidence suggests a repeat troponin at hour 3 from initial EKG reduces potential miss rate from 1.7% to <1% at 30 days. Let them make this decision - ask them if they would want to get admitted or if they are happy to follow up as an out-patient with a week. 

Use Clinical Decision Making rules such as HEART/GRACE score to further risk stratify them and most important - Document medical decision-making and Clinical Decision rules  in the patient's record.

Read more on HEART SCORE on REBELEM.


Take Home:

• A good history helps in risk stratification. Don’t rule out ACS just based on the history alone. With the slightest of concern, get an ECG.
• It is okay to send troponins on your patients if you have some degree of concern but If there are no concerns eat all, then do not send troponins.
• Patients who present with chest pain with suspected cardiac ischaemia based on the history but normal ECG should still undergo further diagnostic testing.
• USA can have an ischemic or normal ECG but should always have negative troponins by definition.
• Low Risk - Do Serial ECGs, Shared Decision Making, Clinical Decision Making Rules to further risk stratify and DOCUMENT the decision making in the medical record. 

Further Reading:

• http://hqmeded-ecg.blogspot.co.uk/2014/04/unstable-angina-dr-braunwald-asks-if-it.html
• http://hqmeded-ecg.blogspot.co.uk/2015/06/unstable-angina-still-exists-beware.html
• https://blog.essentialsofem.com/2016/02/25/low-risk-chest-pain-adp-showdown-using-timi-vs-heart-pt-1-of-3-timi/

Author:

              

     Lakshay Chanana

     

     Speciality Doctor

     Northwick Park Hospital

     Department of Emergency Medicine

     England

     @EMDidactic