If you work in an emergency department setting, you have probably managed patients with borderline positive troponins. We have all ordered a troponin when a patient presents with suspected Acute Coronary syndrome (ACS). This is universally true for all emergency providers. Often, during the review of your labs for this patient you may note the troponin is slightly above normal limits or “borderline”. You will need to make clinical decisions in regards to the management of this patient not only based off the borderline troponin but the patients clinical picture (presentation, history, risk factors, labs, EKG, imaging, etc.).
Questions To Ask
Does this patient need further workup in the emergency department? Does this patient require an admission to the hospital or even observation for serial troponins? Can I safely send the patient home? How do I proceed and what will guide the medical decision making process? Our patients with a borderline positive Troponin need a clear designation. Is this possible/definite ACS or no ACS with Troponin elevation? Let’s also keep in mind that there are several causes of troponin elevation other than myocardial ischemia. But we will focus on ACS as this is an extensive topic.
What is Troponin?
Let us define troponin and identify how to use this lab value to guide our practice in the emergency setting. A cardiac troponin is a serologic test that should be ordered as soon as possible when there is a suspicion for ACS. The troponin is a specific and sensitive biomarker of myocardial injury. It detects biochemical evidence of myocardial injury at lower concentrations and also allows for discrimination of small changes in concentration eve within a normal range. Cardiac troponin achieves peak serum concentration after 12 hours, but can be detected much earlier with newer high-sensitivity tests.
First and foremost, patients who present with signs and symptoms of acute coronary syndrome and who also have ST elevation in two or more contiguous EKG leads need not wait for a troponin value. These patients by definition are having STEMI and need immediate cardiac catheterization. Conversely, symptomatic patients who do not meet STEMI criteria have ACS and must wait for troponin results.
The management of patients with elevated troponins can also vary depending on the patient’s condition. In general, the first point of action revolves around the first troponin result. Patients with a positive troponin and symptoms of ACS are defined as having Non-ST Elevation MI (NSTEMI). Management for NSTEMI includes consultation with a cardiologist, hospital admission, and also likely anticoagulation. Current guidelines from the American College of Cardiology (ACC) suggest that it is safe for patients with NSTEMI to have earlier intervention. We recommend Cardiology consultation for this reason.
Elevated Positive Troponin without ACS
Managing patients who have signs and symptoms of ACS and a positive troponin is pretty straightforward. Patients without symptoms of ACS should not have a troponin drawn or sent. This is what a cardiologist would say. Likewise, a purist might say that the troponin is a specific test designed for a specific condition. However, anyone practicing emergency medicine can attest that our patients are far from specific. In fact, we are surrounded by poor historians, elderly, diabetic, female, weak, short of breath, and [enter any other potential ACS symptom]. For this reason, the troponin has evolved to essentially be a catch-all safety net for our patients. It is very common for patients without clear-cut ACS symptoms to result a positive troponin value. You should admit patients with unexplained positive troponins to the hospital and serial troponins should also be started. Cardiology consultation – which may include stress testing or even catheterization – should also be made.
Patients with a chronically elevated troponin and no clinical suspicion of ischemia should have other reasons explored. These reasons can include, but are not limited to the following:
Rhabdomyolysis with Cardiac Injury
The entire clinical picture may not be clear in the emergency department setting. Often times a delayed diagnosis will present itself. This usually happens after more history Is given and more tests are resulted. For example, patients who have chronic renal failure often have chronically elevated troponins. These patients must have serial troponin concentrations rather than single values to define myocardial injury.
The HEART Score and Positive Troponin
History, ECG, Age, Risk factors, and single high-sensitivity Troponin elevation can be used together as a scoring system to identify clinical risk. This commonly used resource is especially helpful for management of patients who have low to medium risk of ACS.
The Heart Score is a highly validated pathway which allows for the early discharge of
low risk patients from the ED setting without the need for stress testing. Likewise, these patients have been demonstrated to have a 0.4 percent 30-day risk of MI.
There are several online calculators available to help with your management decisions. We recommend that however you use these tools, you carefully document which tool you used in the medical record.
Regardless of your approach, remember that the troponin is a single data point, and does not define your patient by itself. A correct diagnosis is made by a combination of clinical skill, patient history, exam findings, and thought. I hope this brief article helps with your decision making!
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