Approach to Chest Pain: The 4-2-1 Rule
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Example Case
A male patient presents with chest pain. He complains of localized substernal pressure that began 2 hours ago while he was working on his car in the garage. He denies any trauma. He states the pain has been constant since the onset without any specific exacerbating or remitting factors.
He reports mild shortness of breath. He denies fevers, cough, congestion, abdominal pain, nausea, or vomiting. He denies any significant pertinent past medical history and does not take any medications. He smokes 1 pack/day of cigarettes.
Introduction
Chest pain is a common chief complaint presented to healthcare workers, yet the list of potential diagnoses is vast.
Furthermore, some causes of chest pain can be life threatening while others can be managed outpatient.
This can put stress on providers as they do not want to miss an emergent diagnosis.
Having an organized approach to chest pain can help prioritize a list of potential diagnoses and delineate emergent from less emergent causes.
I also came up with the 4-2-1 rule that can be used to help remember the main intrathoracic emergencies that can cause chest pain and hopefully reduce some of that stress.
Using the 4-2-1 rule along with the BREATHE mnemonic for emergent intrathoracic causes of shortness of breath and the UPPER STOMACH mnemonic for emergent causes of upper abdominal pain will help you remember most of the emergent pathology that can cause chest pain.
The main purpose of this blog post is to help provide strategies and considerations on how to best approach the undifferentiated patient with chest pain.
This post is not intended to be a complete comprehensive discussion of all the possible diagnoses for chest pain, nor is it hard fast rules of what definitively should or should not be done.
Each patient will need to be worked up and managed as an isolated case based on the presentation.
However, this post can help provide the tools needed to best optimize the approach to chest pain.
Initial Approach
The first step to managing any patient presenting with chest pain is to perform a primary survey.
Assess the patient’s airway, breathing, and circulation along with the vital signs.
Ask yourself, does the patient look sick or not sick?
IV access and EKG should be obtained immediately upon arrival as the patient is hooked up to the cardiac monitor and pulse oximetry.
Quick Chart Review
If the patient is stable and time allows, performing a quick chart review can provide useful preliminary information about the patient that may help to risk stratify them and create an initial differential.
A chart review does not take much time and can provide pertinent information.
Review the patient’s age, sex, past medical history, social history, medications, vital signs, previous cardiac catheterizations, previous echocardiograms, previous EKGs, and previous healthcare visits/results for similar complaints.
This is not a complete list but serves as an example of some of the information that can be obtained.
Understanding the patient better from a quick chart review can help to prepare you before entering the room, and it may also drive you to ask more detailed questions related to certain diagnoses.
However, it is crucial to use caution with a chart review as to not let it bias you or create premature closure on one particular diagnosis as this could cause you to miss something.
Chest Pain Chart Review Considerations
Vital Signs
Age
Sex
Past medical history, social history, family history, surgical history
Medications
Previous echocardiogram
Previous cardiac catheterization
Previous CT chest or chest x-rays
Previous healthcare visits for similar complaints
Previous EKG
4-2-1 Rule
The list of diagnoses that can cause chest pain is extensive. Furthermore, some etiologies can be life threatening while others are less urgent.
Below demonstrates how many diagnoses are out there that can lead to chest pain.
The above list can be overwhelming and puts pressure on healthcare workers to make sure they are not missing an emergent cause to the patient’s chest pain.
Fortunately, not every diagnosis is life threatening.
Therefore, the first step in every patient with chest pain is to rule out or at least consider the emergent causes.
I developed the 4-2-1 rule as an easy way to remember the 7 main intrathoracic emergencies that cause chest pain.
That is not to say other causes of chest pain cannot become life threatening, but these are the main ones.
I call it the 4-2-1 rule because there are:
4 heart related emergencies to consider (4 chambers in the heart): ACS, aortic dissection, pericarditis/myocarditis, pericardial effusion/tamponade
2 lung related emergencies (2 lungs in the body): PE and pneumothorax
1 esophageal related emergency (1 esophagus in the body): esophageal perforation.
Remembering the 4-2-1 rule will help you consider the main intrathoracic chest pain emergencies in each patient.
Chest Pain Differential
In addition to the 4-2-1 rule for chest pain emergencies, you can also apply the BREATHE mnemonic for shortness of breath emergencies to create a more comprehensive list of diagnoses as chest pain and shortness of breath can overlap.
Once the 4-2-1 rule and the BREATHE mnemonic have been ruled out or at least considered in each patient with chest pain, then there are many other diagnoses that can cause similar complaints.
It is challenging to remember every single one. The best way to approach this is to organize the diagnoses into intrathoracic and extrathoracic sources, and go by organ system/body part.
Use clues from the history, physical, and work up to support or negate them as a possible etiology.
First, consider intrathoracic sources: heart, lungs, aorta, esophagus, chest wall.
Next, consider extrathoracic sources that could be causing referred pain: abdomen, skin, psychiatric, toxidromes.
This is to help ensure that you are at least considering as much as possible. Then once you have obtained your history and physical, you can refine and/or prioritize your differential.
Below is not intended to be an exhaustive list, but rather an example of how you could organize your thoughts and approach your differential.
Chest Pain Differential = Organize by Intrathoracic and Extrathoracic Sources
Intrathoracic Sources
Heart - ACS, stable angina, pericarditis, myocarditis, pericardial effusion/tamponade, valvular disease, coronary dissection, coronary spasm, endocarditis
Aorta - aortic dissection, aortic aneurysm
Lungs - pulmonary embolism, pneumothorax, pneumonia, pleurisy/pleuritis, foreign body aspiration, asthma, COPD
Chest wall - contusion, costochondritis, rib fracture
Esophagus - esophagitis, achalasia, food impaction, esophageal perforation, GERD, esophageal spasm
Extrathoracic Sources
Abdominal source - cholecystitis, hepatitis, gastritis, peptic ulcer disease, pancreatitis, nephrolithiasis
Skin - herpes zoster
Psychiatric - anxiety, panic attack, stress reaction
Toxidrome - sympathomimetic use, cocaine
History of Present Illness
Obtaining a thorough history and having a clear understanding about the onset and nature of the chest pain is important as this can help to prioritize your differential.
For example, understanding if the pain is sharp, pleuritic, pressure, squeezing, crushing, tearing, burning, sudden onset, trauma induced, gradual, postprandial, exertional, improved with rest, localized, radiating, etc. will all be helpful.
Unfortunately, there is no textbook presentation for any cause of chest pain, and symptoms can vary and overlap between diagnoses.
At the end of this post there are example buzzwords and presentations commonly tested on exams and boards.
Once you have had the patient provide as much information as they can, then ask any additional questions that may help to refine your differential.
First, focus on any additional questions you may have pertaining to the 4-2-1 rule of emergent causes.
Then consider other diagnoses by performing a review of systems and asking questions by organ system.
Lastly, make sure to ask questions about other non-chest related diagnoses such as panic attacks, anxiety, abdominal etiologies, toxidromes, etc.
Physical Examination
Chest pain physical examination may include, but is not limited to, auscultation of the heart and lungs, palpation of the chest and back, abdominal examination, assessment of jugular veins, assessment of lower extremities for edema or calf tenderness, assessment of pulses, neurological examination, and assessment of skin overlying area of pain.
Diagnostic Investigation
Upon completion of the primary survey, history, and physical examination, you will likely have a fairly refined and prioritized differential for the patient’s chest pain.
Work up will be based on your differential and will be used to further support or potentially negate the etiologies in your list. Work up considerations include:
All Patients
Nearly all patients with chest pain should receive an EKG and chest x-ray.
Higher Risk Patients
Additional testing should be considered for patients that are higher risk or with concomitant comorbidities.
This may include CBC, chemistry, troponin, and coagulation studies in addition to their EKG and chest x-ray.
Consideration can also be given to d-dimer and BNP.
Advanced imaging such as a CT chest may be required depending on the differential and diagnostic results.
If ultrasound savvy, performing a bedside ultrasound to assess the heart, lungs, aorta, abdomen, and IVC can be useful.
Atypical or Referred Pain
If there is concern for potential abdominal etiologies, then consideration should also be given to LFTs, lipase, lactate, pregnancy test, and urinalysis in addition to work up above.
If abdominal imaging is required considerations can be given to (depending on what is being assessed) upright chest x-ray/abdominal series (free air, obstructive findings), RUQ US (hepatobiliary etiologies), CT abdomen/pelvis, or aortic ultrasound.
If concerned about toxidromes then urine drug screen and toxicology work up may be warranted.
Risk Stratification and Tools
The purpose of this section is to acknowledge risk stratification tools that exist as they may be encountered.
It is not meant to provide management or treatment advice. Scoring systems and tools are just that, and they are not meant to provide concrete instructions on how to manage the patient.
The care should ultimately be up to the provider based on the case at hand. All scoring systems and tools can be found online.
Pulmonary Embolism
Wells Criteria
Wells criteria can be used to help determine the pretest probability of PE and to help risk stratify patients for PE. Risk stratifying the patient can help to create a diagnostic approach to PE.
Generally, low risk patients for PE (Wells score of 0-4) can be considered for a d-dimer. If the d-dimer is negative, then no further work up for PE can be considered. If the test is positive, then a CT PE study should be considered to further rule out PE.
If the patient is high risk for PE (Wells score >4), then a CT PE study can be considered without obtaining a d-dimer first. Again these are not hard fast rules and each case will need to be managed on a case by case basis.
Clinical signs and symptoms of DVT? (3 points)
PE #1 on differential or equally likely (3 points)
Heart rate > 100 (1.5 points)
Immobilization > 3 days or surgery < 4 weeks (1.5 points)
Previously diagnosed DVT or PE (1.5 points)
Hemoptysis (1 point)
Malignancy with treatment last 6 months (1 point)
PERC Rule
The PERC rule is primarily designed for patients who are low risk for PE.
If a patient does not have any of the PERC criteria present and they are low risk for PE, then no further diagnostic testing for PE can be considered.
If the patient does have 1 or more criteria present, then the PERC rule cannot be applied and consideration should be given to order a d-dimer if they are low risk for PE or straight to a CT PE study if they are high risk (although if they are high risk, PERC rule typically should not be applied).
If any of the questions below are answered yes, then the PERC rule cannot be applied for ruling out PE.
Age >/= 50?
Heart Rate > 100?
Oxygen saturation < 95% on room air?
Unilateral leg swelling?
Hemoptysis?
Recent surgery/trauma?
Prior PE/DVT?
Hormone use?
Acute Coronary Syndrome
Heart Score
The heart score is designed to predict the likelihood of an adverse cardiac event at 6 weeks.
Generally a score of 0-3 is low risk and these patients can be considered for discharge, a score of 4-6 is moderate risk and these patients can be considered for admission for further testing, and scores >7 are high risk and these patients should be considered for admission and possible early intervention.
As above, this is simply a tool and decisions need to be made on a case by case basis. The 5 criteria that get factored into calculating a patient’s heart score is:
Clinical suspicion
EKG
Age
Risk factors
Initial troponin
TIMI Score
The TIMI score is designed to estimate mortality, risk of new or recurrent MI, or risk of severe recurrent ischemia requiring urgent revascularization in patients with unstable angina or NSTEMI.
Each criteria listed below is 1 point, and the total number of points correlates to a percent risk of mortality, MI, or need for revascularization.
Age >/= 65
>/= 3 CAD risk factors
Known CAD
ASA use in past 7 days
Severe angina
Positive cardiac marker
EKG ST changes >/= 0.5mm
Exam and Board Prep
Board, medical, and licensure exams commonly use buzzwords or phrases within the question stem. Knowing these will help you quickly associate what the examiner is testing you on.
Below are descriptions you may see on exams that correlate with that particular diagnosis.
Use caution clinically, however, as many patients with chest pain do not present with the classic textbook symptoms. For example, burning chest pain after meals can still be ACS and not GERD.
Conclusion
I hope that helps to organize your approach to chest pain.
Remember the 4-2-1 rule for intrathoracic emergent causes of chest pain that should always be considered: 4 heart related emergencies (ACS, aortic dissection, pericarditis/myocarditis, pericardial effusion/tamponade), 2 lung related emergencies (PE and pneumothorax), and 1 esophageal related emergency (esophageal rupture).
Apply the BREATHE mnemonic as well for shortness of breath emergencies for a more comprehensive emergent differential.
Obtaining a thorough history about the nature of the pain can help to delineate and prioritize your differential.
Work up should be based on ruling out emergent causes and investigating your most likely differential diagnoses.
You can also use risk stratification tools to assist with your decisions.
Lastly, there are buzzwords for each chest pain presentation that are commonly used on exams and licensure boards. Knowing these will help you to identify what the examiner is testing for.
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