What is the best course of action for a patient with palpitations and shortness of breath (SOB), potentially with a history of cardiovascular disease or respiratory conditions?

Evaluation and Management of Palpitations with Shortness of Breath

For any patient presenting with palpitations and shortness of breath, immediately assess hemodynamic stability and perform a 12-lead ECG within minutes of contact—this is your diagnostic cornerstone and will guide all subsequent management. 1, 2

Immediate Assessment and Stabilization

First 5 Minutes: Hemodynamic Status

• Check vital signs immediately: blood pressure, heart rate, respiratory rate, and oxygen saturation 1
• If hemodynamically unstable (systolic BP <90 mmHg, altered mental status, severe respiratory distress, or signs of shock): prepare for synchronized cardioversion while obtaining IV access 1
• If stable: proceed with systematic evaluation while maintaining continuous cardiac monitoring 1

Obtain 12-Lead ECG Immediately

• The ECG is the gold standard for diagnosis and must be performed on presentation 2, 3
• Look specifically for:
  • Tachyarrhythmias: supraventricular tachycardia (SVT), atrial fibrillation, atrial flutter, or ventricular tachycardia 1
  • Pre-excitation patterns: delta waves suggesting Wolff-Parkinson-White syndrome 4
  • ST-segment changes: elevation (acute MI, pericarditis) or depression (ischemia) 1, 5
  • Structural clues: left ventricular hypertrophy, chamber enlargement 1

Critical History Elements

Symptom Characterization

• Onset and duration: sudden versus gradual, seconds versus hours 1, 2
• Associated symptoms requiring urgent evaluation 1, 2:
  • Chest pain or pressure (consider acute coronary syndrome)
  • Syncope or near-syncope (suggests hemodynamically significant arrhythmia)
  • Severe dyspnea or orthopnea (acute heart failure)
  • Diaphoresis (autonomic instability)

Red Flag Features

• Recent weight loss, heat intolerance, tremor: thyroid storm can precipitate life-threatening arrhythmias 4
• Recent viral illness: suggests possible myocarditis or pericarditis 5
• Known structural heart disease: dramatically increases risk of malignant arrhythmia 1, 3

Diagnostic Workup

Essential Initial Tests

• Continuous cardiac monitoring: institute within minutes of patient contact 1
• Laboratory evaluation 1:
  • Troponin (rule out acute coronary syndrome)
  • Thyroid-stimulating hormone (TSH) and free T4 (thyrotoxicosis)
  • Electrolytes, particularly potassium and magnesium (arrhythmogenic if abnormal)
  • Complete blood count (anemia can cause compensatory tachycardia)
  • BNP or NT-proBNP if heart failure suspected

Transthoracic Echocardiography

• Perform early TTE in all patients with suspected heart failure to confirm diagnosis, quantify left ventricular function, assess valvular disease, and identify structural abnormalities 1
• Urgent echocardiography indicated if 1:
  • Hemodynamic instability
  • New murmur on examination
  • Suspected acute valvular dysfunction
  • Signs of tamponade or pericardial effusion

Extended Monitoring if Initial ECG Non-Diagnostic

• 24-48 hour Holter monitor if arrhythmia not captured on initial ECG but high clinical suspicion 1, 2
• Inpatient telemetry for 24-48 hours if syncope of unknown origin or high suspicion for arrhythmic cause 1

Management Based on Specific Findings

Acute Supraventricular Tachycardia (e.g., AVNRT)

1. First-line: vagal maneuvers (Valsalva in supine position for 10-30 seconds, carotid massage after confirming no bruit) 1
2. If unsuccessful: IV adenosine 6 mg rapid push, followed by 12 mg if needed (terminates AVNRT in ~95% of cases) 1
3. If adenosine fails or not feasible: IV beta-blockers, diltiazem, or verapamil 1
4. If hemodynamically unstable: synchronized cardioversion 1

Acute Heart Failure with Congestion

• Oxygen therapy if SpO2 <90% or based on clinical judgment 1
• Non-invasive ventilation for respiratory distress 1
• IV diuretics (furosemide) for volume overload 1
• Vasodilators if blood pressure permits (most AHF patients present with normal or high BP) 1
• Maintain systolic BP >90 mmHg and adequate peripheral perfusion 1

Atrial Fibrillation with Rapid Ventricular Response

• Rate control: IV beta-blockers, diltiazem, or verapamil to slow AV nodal conduction 1
• Anticoagulation with heparin if new-onset or hemodynamically significant 1
• Electrical cardioversion if hemodynamically unstable 1
• Avoid beta-blockers in acute decompensated heart failure or severe bronchospastic disease 1

Common Pitfalls to Avoid

• Do not delay ECG acquisition: waiting for laboratory results or detailed history before obtaining ECG can miss time-sensitive diagnoses 2, 3
• Do not assume benign etiology in patients with structural heart disease: heart disease is the major predictor of risk for death or significant arrhythmia in patients with palpitations 1
• Do not misinterpret agonal gasps as normal breathing: this is a manifestation of cardiac arrest requiring immediate CPR 1
• Do not use beta-blockers in patients with severe conduction abnormalities or sinus node dysfunction: these can be exacerbated 1
• Do not confuse early repolarization with acute pericarditis on ECG: clinical context (positional chest pain, recent viral illness, pericardial friction rub) is essential 5

Disposition Decisions

Admit for Inpatient Monitoring If:

• Syncope of unknown origin 1
• Hemodynamic instability at any point 1
• Acute heart failure requiring IV therapy 1
• High-risk arrhythmia (ventricular tachycardia, symptomatic bradycardia, high-grade AV block) 1
• Suspected acute coronary syndrome 1

Outpatient Management Acceptable If:

• Benign etiology confirmed (sinus tachycardia from anxiety, caffeine, deconditants) 2, 3
• Stable chronic atrial fibrillation with adequate rate control 1
• No structural heart disease and reassuring workup 2
• Ensure cardiology follow-up within 1-2 weeks 1