Key Takeaways
- Acute coronary syndrome (ACS) includes unstable angina, NSTEMI, and STEMI, all caused by reduced blood flow to the myocardium
- OPQRST is the standard mnemonic for assessing chest pain: Onset, Provocation, Quality, Radiation, Severity, Time
- Classic MI signs include crushing substernal chest pain, diaphoresis, dyspnea, nausea, and radiation to the left arm or jaw
- EMTs can assist with prescribed nitroglycerin if systolic BP is above 100 mmHg and the patient has not taken erectile dysfunction medications within 24-48 hours
- Aspirin 160-325 mg should be given to suspected ACS patients unless allergic or contraindicated, and the patient should chew it for faster absorption
- Women, diabetics, and elderly patients may present with atypical MI symptoms such as fatigue, nausea, back pain, or shortness of breath without classic chest pain
- Angina is relieved by rest and nitroglycerin; MI pain typically persists despite rest and nitroglycerin administration
Cardiac Emergencies & Chest Pain Assessment
Cardiac emergencies are a leading cause of death in the United States. An EMT's ability to quickly assess and manage these emergencies can mean the difference between life and death.
Acute Coronary Syndrome (ACS)
Acute coronary syndrome is an umbrella term for conditions caused by sudden reduction in blood flow to the heart muscle:
| Condition | Description | Key Features |
|---|---|---|
| Stable Angina | Temporary chest pain due to exertion or stress | Predictable, relieved by rest/nitroglycerin, lasts <15 min |
| Unstable Angina | Chest pain that occurs at rest or is worsening | Unpredictable, may not resolve with rest/NTG, higher risk |
| NSTEMI | Partial blockage causing cardiac muscle damage | Elevated troponin, no ST elevation on ECG |
| STEMI | Complete blockage causing significant muscle death | ST elevation on ECG, emergent cardiac catheterization needed |
Pathophysiology: Most ACS events occur when an atherosclerotic plaque in a coronary artery ruptures, causing a blood clot (thrombus) to form. This clot partially or completely blocks blood flow to the myocardium.
OPQRST Pain Assessment
When assessing a patient with chest pain, use the OPQRST mnemonic:
| Letter | Stands For | Questions to Ask |
|---|---|---|
| O | Onset | "When did the pain start? What were you doing?" |
| P | Provocation/Palliation | "What makes it better or worse? Does anything change it?" |
| Q | Quality | "Can you describe the pain? Pressure, sharp, burning?" |
| R | Radiation | "Does the pain go anywhere else? Arm, jaw, back?" |
| S | Severity | "On a scale of 0-10, how bad is the pain?" |
| T | Time | "How long have you had this pain? Is it constant or intermittent?" |
Signs and Symptoms of Myocardial Infarction
Classic (typical) presentation:
- Crushing, squeezing substernal chest pain (described as "elephant sitting on my chest")
- Diaphoresis (profuse sweating)
- Dyspnea (shortness of breath)
- Nausea and/or vomiting
- Radiation of pain to the left arm, jaw, neck, back, or epigastric area
- Anxiety or feeling of impending doom
- Pale, cool, clammy skin
- Weakness and fatigue
Atypical presentations (common in women, elderly, diabetics):
- Fatigue or generalized weakness without chest pain
- Shortness of breath as the only symptom
- Nausea, vomiting, or indigestion
- Pain in the back, jaw, or between the shoulder blades
- Dizziness or syncope
- Sudden onset of anxiety
Important: Up to 30% of women experiencing an MI may not have classic chest pain. Always maintain a high index of suspicion.
Nitroglycerin Administration (EMT Assist)
EMTs can assist patients with their own prescribed nitroglycerin under medical direction:
Indications:
- Patient has chest pain consistent with cardiac origin
- Patient has their own prescribed nitroglycerin
- Medical direction authorizes administration
- Systolic blood pressure is greater than 100 mmHg
Contraindications:
- Systolic BP less than 100 mmHg (or per local protocol)
- Patient has taken erectile dysfunction medication (sildenafil/Viagra within 24 hours, tadalafil/Cialis within 48 hours)
- Head injury with increased intracranial pressure
- Patient has already taken the maximum dose (usually 3 doses)
- Infant or child patient
- The medication is not prescribed to the patient
Administration:
- Confirm order with medical direction
- Check blood pressure (must be >100 mmHg systolic)
- Have patient lift tongue
- Place 1 tablet (0.4 mg) sublingually or 1 spray under the tongue
- Reassess blood pressure in 2 minutes
- May repeat every 3-5 minutes up to 3 total doses if pain persists and BP remains adequate
- Monitor for hypotension, headache, and changes in pain level
Aspirin Administration
Aspirin is a critical early intervention for suspected ACS:
Dosage: 160-325 mg (commonly one adult aspirin 325 mg, or two to four baby aspirin 81 mg each)
Route: Chewed (not swallowed whole) for faster absorption
Indications:
- Signs and symptoms of ACS
- No known allergy to aspirin
- Authorized by medical direction or protocol
Contraindications:
- Known aspirin allergy
- Active GI bleeding or bleeding disorders
- Patient already took aspirin today
- Patient unable to swallow
- Children (risk of Reye syndrome)
12-Lead ECG Application (EMT Level)
While interpretation of 12-lead ECGs is typically a paramedic-level skill, many EMS systems train EMTs to apply the leads:
- Purpose: Allows early identification of STEMI for hospital pre-notification
- Transmission: ECG can be transmitted to the receiving hospital for early catheterization lab activation
- Placement: 10 electrodes placed on specific anatomical landmarks (4 limb leads, 6 precordial leads)
- EMT role: Apply leads correctly, transmit if equipped, recognize "STEMI alert" from monitor prompts
A 58-year-old male presents with crushing chest pain, diaphoresis, and nausea. He has prescribed nitroglycerin and his blood pressure is 88/60 mmHg. What should you do?
What is the recommended dose of aspirin for a patient with suspected acute coronary syndrome?
Which presentation is considered an atypical sign of myocardial infarction?
What does the "R" in the OPQRST mnemonic stand for?
Which of the following is a contraindication to assisting with nitroglycerin?
What is the key difference between stable angina and myocardial infarction?
Which of the following are contraindications to assisting a patient with nitroglycerin? (Select all that apply)
Select all that apply