What is the initial management for an adult patient with no known medical history presenting with tachycardia and chest pain?

Initial Management of Tachycardia with Chest Pain

For an adult with tachycardia and chest pain, immediately assess hemodynamic stability—if the patient shows hypotension, altered mental status, acute heart failure, or shock, proceed directly to synchronized cardioversion without delay for diagnostic workup. 1, 2

Immediate Assessment and Stabilization

First 60 Seconds: Vital Signs and Monitoring

• Attach cardiac monitor, obtain vital signs including blood pressure and heart rate, establish IV access, and assess oxygen saturation 2
• Provide supplemental oxygen if hypoxemia or respiratory distress is present, as hypoxemia commonly drives tachycardia 2
• Evaluate for signs of increased work of breathing (tachypnea, intercostal retractions, suprasternal retractions) 3

ECG Within 10 Minutes

• Obtain and interpret a 12-lead ECG within 10 minutes of arrival to identify ST-segment elevation myocardial infarction (STEMI) 3
• However, do not delay cardioversion to obtain a 12-lead ECG in unstable patients—immediate treatment takes priority 1, 2
• If initial ECG is nondiagnostic and symptoms persist, perform serial ECGs to detect ischemic changes 3

Hemodynamic Stability Assessment

Unstable Patient (Immediate Cardioversion Required)

The patient is unstable if tachycardia is causing any of the following 1, 2:

• Hypotension or signs of shock
• Acute altered mental status
• Ischemic chest pain
• Acute heart failure (pulmonary edema)
• Severe dyspnea

For unstable patients: sedate if conscious and time permits, then perform immediate synchronized cardioversion 1, 2. Do not attempt adenosine, beta-blockers, or amiodarone as first-line therapy in hemodynamically unstable patients—adenosine risks worsening hypotension, amiodarone takes 30 minutes to work, and beta-blockers have negative inotropic effects 1.

Stable Patient (Diagnostic Workup Proceeds)

If the patient is hemodynamically stable, proceed with focused history and diagnostic evaluation 3:

History Elements to Obtain

• Nature of chest pain: Retrosternal discomfort (pressure, tightness, squeezing) suggests angina; sharp pain worsening with inspiration suggests pericarditis 3
• Onset and duration: Anginal symptoms build gradually over minutes; sudden ripping pain radiating to the back suggests aortic dissection 3
• Associated symptoms: Palpitations, dyspnea, dizziness, or syncope 4, 5
• Cardiovascular risk factors: Prior coronary disease, diabetes, hypertension, smoking 3

Cardiac Biomarkers

• Measure cardiac troponin (preferably high-sensitivity troponin) as soon as possible after presentation 3
• Obtain serial troponin at 6-12 hours if initial value is normal and suspicion for acute coronary syndrome (ACS) remains 3
• Elevated troponin indicates myocardial injury and mandates treatment per ACS protocols 3

Chest Radiograph

• Obtain chest X-ray to evaluate for other cardiac, pulmonary, and thoracic causes of symptoms (pneumothorax, pneumonia, aortic dissection, pulmonary embolism) 3

Tachycardia-Specific Considerations

Rate Threshold for Clinical Significance

• Heart rates >150 beats per minute are more likely to represent primary arrhythmias requiring treatment 3
• Heart rates <150 beats per minute are more likely secondary to underlying conditions (fever, dehydration, anemia, hypoxia) unless ventricular dysfunction is present 3

Sinus Tachycardia

If the rhythm is sinus tachycardia, do not treat the rate itself—identify and treat the underlying cause (pain, anxiety, hypovolemia, hypoxia, anemia, fever) 3. Normalizing heart rate in compensatory tachycardia can be detrimental when cardiac output depends on the rapid rate 3, 2.

Supraventricular Tachycardia (SVT)

For stable patients with regular narrow-complex tachycardia suggestive of SVT 4, 5:

• Attempt vagal maneuvers (Valsalva maneuver is safer and more efficacious than carotid massage, especially in elderly) 4
• If vagal maneuvers fail, adenosine is first-line pharmacotherapy (6 mg rapid IV push, followed by 12 mg if needed) 3, 4
• Never give adenosine to unstable patients with hypotension 1

Wide-Complex Tachycardia

Presume wide-complex tachycardia is ventricular tachycardia and cardiovert immediately in unstable patients 1, 2. Even if the arrhythmia self-terminates, urgent cardiology consultation and echocardiography are required 1, 2.

Critical Pitfalls to Avoid

• Never delay cardioversion in unstable patients while obtaining diagnostic tests 1, 2
• Never use AV nodal blocking agents (adenosine, beta-blockers, calcium channel blockers) in pre-excited atrial fibrillation, as this accelerates ventricular response and can cause cardiac arrest 2
• Never give adenosine for irregular or polymorphic wide-complex tachycardia 2
• Never attempt to normalize heart rate when tachycardia is compensatory (e.g., in shock, heart failure with poor cardiac function) 3, 2

Disposition and Follow-Up

Immediate Cardiology Consultation Required For:

• Any suspected ventricular tachycardia, even if self-terminated 1, 2
• Elevated troponin with ECG changes 3
• Recurrent ischemia or hemodynamic instability 3
• Pre-excitation with irregular palpitations (suggests atrial fibrillation with Wolff-Parkinson-White syndrome—sudden death risk) 2, 5

Outpatient Referral Appropriate For:

• Drug-resistant or drug-intolerant narrow-complex tachycardia 2
• Patients desiring freedom from long-term drug therapy (catheter ablation option) 2, 5
• Clear history of paroxysmal regular palpitations 2