What lab work and diagnostic tests are recommended for palpitations?

Recommended Laboratory and Diagnostic Tests for Palpitations

For patients presenting with palpitations, a 12-lead ECG, basic laboratory testing, and ambulatory ECG monitoring are the essential initial diagnostic tests, with additional testing guided by clinical findings. 1, 2

Initial Evaluation

Essential Laboratory Tests

• Complete blood count
• Serum electrolytes (particularly potassium, magnesium, calcium)
• Blood urea nitrogen and serum creatinine
• Fasting blood glucose and glycohemoglobin (HbA1c)
• Thyroid-stimulating hormone (TSH)
• Liver function tests
• Lipid profile 2

Mandatory Initial Cardiac Testing

• 12-lead ECG (Class I recommendation) 1
• Chest radiograph 2

Ambulatory ECG Monitoring

The choice of monitoring device depends on symptom frequency:

• 48-hour ambulatory ECG monitoring (Holter): First-line for patients with frequent palpitations (Class I recommendation) 1
• External event recorder or patch monitor: For less frequent episodes occurring within 2-4 weeks
• Implantable loop recorder (ILR): Consider for patients with infrequent but concerning palpitations when other monitoring fails to identify a cause (Class IIb recommendation) 1

Additional Testing Based on Clinical Suspicion

Echocardiography

• Recommended when:
  • Suspected structural heart disease
  • Abnormal cardiac examination
  • Abnormal ECG findings
  • Palpitations during exertion
  • Family history of sudden cardiac death 2

Exercise Stress Testing

• Indicated when:
  • Palpitations occur during or after exercise
  • Suspicion of exercise-induced arrhythmias
  • Chest pain associated with palpitations suggesting ischemia 1

Electrophysiological Studies (EPS)

• Reserved for:
  • Persistent or recurrent supraventricular tachycardia
  • Evidence of sino-atrial disease or AV block
  • Ventricular pre-excitation
  • Documented sustained ventricular tachycardia 1

Risk Stratification

High-Risk Features Requiring Urgent Evaluation

• Palpitations with syncope or pre-syncope
• Palpitations during exertion
• Family history of sudden cardiac death
• Known structural heart disease
• Abnormal ECG (conduction disorders, ventricular pre-excitation)
• Hemodynamic compromise during symptoms 2

Special Considerations

Post-COVID-19 Palpitations

For patients with palpitations following COVID-19 infection (PASC-CVS), consider:

• Basic laboratory testing including cardiac troponin
• ECG
• Echocardiogram
• Ambulatory rhythm monitor
• Chest imaging (X-ray and/or CT)
• Pulmonary function tests 1

Pitfalls to Avoid

• Performing echocardiography in all patients with palpitations (low yield in those without clinical evidence of cardiac disease)
• Relying solely on 24-hour Holter monitoring for infrequent symptoms
• Failing to correlate symptoms with recorded arrhythmias
• Overlooking non-cardiac causes (anxiety, thyroid disease, anemia, stimulant use)

Follow-up Recommendations

• If initial evaluation is negative but symptoms persist, consider extended monitoring
• Cardiology consultation for abnormal findings, known cardiovascular disease with new symptoms, or persistent unexplained symptoms 1
• Reassess diagnosis if symptoms change in character or frequency

By following this systematic approach, clinicians can efficiently diagnose the cause of palpitations while minimizing unnecessary testing and optimizing patient outcomes.