What testing is recommended for palpitations (irregular heart rhythms)?

Testing for Palpitations

For patients with frequent or sustained palpitations, 48-hour ambulatory ECG monitoring is the recommended first-line test to identify the likely cause. 1, 2, 3

Initial Diagnostic Workup

Essential First Steps

• 12-lead ECG is mandatory for all patients presenting with palpitations to identify baseline rhythm abnormalities, pre-excitation patterns, conduction defects, and signs of structural heart disease 1, 2, 3
• Look specifically for: pre-excitation (WPW syndrome), QT prolongation, Brugada pattern, signs of hypertrophic cardiomyopathy, prior infarction, or ventricular hypertrophy 1

Targeted Laboratory Testing

Avoid routine comprehensive laboratory panels - they have been shown to be not useful in palpitation evaluation 2, 4

Order labs only when clinically indicated based on history and exam: 2, 4

• Thyroid-stimulating hormone (TSH) if thyroid symptoms present
• Complete blood count if anemia suspected
• Serum electrolytes (including calcium and magnesium) if electrolyte disturbance suspected
• Fasting glucose if hypoglycemia or diabetes suspected
• BNP and high-sensitivity troponin may be considered if cardiac cause suspected, though usefulness is uncertain 2

Ambulatory ECG Monitoring Strategy

The choice of monitoring depends on symptom frequency: 2, 3, 5

For Daily Palpitations

• 24-48 hour Holter monitoring is appropriate 4, 3, 5

For Weekly Episodes

• External event recorder or wearable loop recorder for 2-4 weeks 3, 5
• 30-day external continuous monitoring may be considered 6

For Infrequent Episodes (Monthly or Less)

• Implantable loop recorder (ILR) should be considered when no cause is identified after prolonged ECG monitoring 1, 2, 3
• ILR is particularly useful for patients with recurrent unexplained palpitations who are at low risk of sudden cardiac death 1, 2

Structural Heart Disease Evaluation

Echocardiography Indications

Order echocardiography when: 1, 3

• Documented sustained palpitations to exclude structural heart disease
• Abnormal ECG findings suggesting cardiomyopathy
• Clinical suspicion of valvular disease, hypertrophic cardiomyopathy, or tachycardia-mediated cardiomyopathy
• Physical exam suggests structural abnormality

Echocardiography is recommended for all patients with suspected or known ventricular arrhythmias 1

Advanced Cardiac Imaging

• Cardiac MRI or CT should be considered when echocardiography does not provide accurate assessment of left or right ventricular function 1

Exercise Testing

Exercise ECG is indicated when: 1, 3

• Palpitations are triggered by exertion
• Evaluating for exercise-induced arrhythmias (CPVT, catecholaminergic VT)
• Assessing for silent ischemia in patients with intermediate probability of coronary disease
• Testing response to therapy in adrenergic-dependent arrhythmias

Important caveat: Exercise testing in patients with life-threatening arrhythmias should only be performed where resuscitation equipment and trained personnel are immediately available 1

Electrophysiological Studies

EPS is NOT routinely recommended for palpitations 1

EPS is Indicated When: 1

• Palpitations preceding syncope in patients with structural heart disease
• Documented sustained ventricular tachycardia requiring ablation assessment
• Pre-excitation (WPW) identified on ECG with symptomatic tachycardia
• Persistent or recurrent supraventricular tachycardia requiring ablation

EPS Has Low Yield For: 1

• Unexplained palpitations without documented arrhythmia
• Patients without structural heart disease

Immediate Specialist Referral Criteria

Refer immediately to cardiac electrophysiology for: 4, 3

• Wolff-Parkinson-White syndrome (pre-excitation on ECG with paroxysmal palpitations) - due to risk of sudden death
• Wide complex tachycardia of unknown origin
• Severe symptoms during palpitations (syncope, presyncope, severe dyspnea)
• Drug-resistant or drug-intolerant narrow complex tachycardia
• Pre-excitation with irregular palpitations (suggests atrial fibrillation with accessory pathway)

Critical Pitfalls to Avoid

• Do NOT start class I or III antiarrhythmics empirically without documented arrhythmia 4
• Do NOT order comprehensive laboratory panels routinely - target testing based on clinical suspicion 2, 4
• Do NOT rely on automatic ECG interpretation - these systems are unreliable and frequently incorrect 4
• Do NOT dismiss syncope occurring with palpitations - this requires urgent evaluation 4, 3

Special Population: Hypertrophic Cardiomyopathy

Patients with HCM and palpitations require: 4, 3

• 24-48 hour ambulatory monitoring every 1-2 years as part of routine follow-up
• Extended monitoring if additional atrial fibrillation risk factors present (left atrial dilatation, advanced age, NYHA class III-IV)