Approach to chest pain: Clinical sciences

Chest pain is a common chief complaint, with a broad differential diagnosis that includes some potentially life-threatening causes. So your workup needs to focus on ruling out these dangerous causes before considering more benign ones. 

Let’s take a look at this approach. 

Your first step in evaluating a patient presenting with chest pain is to systematically assess their ABCDEs, which stands for airway, breathing, circulation, then disability and exposure. This helps you judge if the patient is stable or unstable, so you can treat any issues at each step. Your patient may, for example, require endotracheal intubation.   
In an unstable patient, your priority is to stabilize their airway, breathing, and circulation. Once they are stabilized, your next step is to evaluate for life-threatening causes of chest pain, such as ST-elevation myocardial infarction or STEMI for short, cardiac tamponade, aortic dissection, pulmonary embolism, or tension pneumothorax. And remember, even if your patient is stable, it does not rule out these life-threatening conditions.   
So what do you do in the case of a stable patient presenting with chest pain?  

Your evaluation begins with a focused history and physical examination, or H&P, alongside an electrocardiogram, or ECG. That ECG needs to be performed and interpreted promptly! You’re going to use it to evaluate the patient for some life-threatening conditions.  

At the same time, if you suspect the patient has a critical illness or might become unstable, acute management will be required. First, place them on continuous cardiac monitoring with pulse oximetry and establish IV access. If they are hypoxemic, you should also provide supplemental oxygen. 

Okay, now that you’ve done the history and physical, the ECG, and acute management, it’s time to check for the acute coronary syndrome or ACS.  

The first condition to look for is an ST-elevation myocardial infarction, or STEMI. 
 
In an ECG, look for localized ST-elevations in 2 contiguous leads. If present, that’s diagnostic for a STEMI. 
  
However, a left bundle branch block or LBBB can mask ST elevation, so the diagnosis can also be made if there’s a new LBBB with a presentation consistent with ACS. LBBB typically presents as QRS longer than 120ms, a dominant S wave in V1, and broad notched R waves and absent Q waves in the lateral leads, like V6.   
If there is no ECG evidence of a STEMI, you need to assess clinical findings for other immediately life-threatening conditions.