What is the initial workup for a patient presenting with palpitations?

Initial Workup for Palpitations

All patients presenting with palpitations require an immediate 12-lead ECG, detailed history focusing on rhythm characteristics (regular vs. irregular, sudden vs. gradual onset/termination), and targeted physical examination—this triad forms the foundation of diagnosis and determines all subsequent testing. 1, 2

Immediate Assessment

History - Critical Pattern Recognition

• Characterize the rhythm pattern: Regular vs. irregular is the single most important distinguishing feature 1
• Onset and termination: Sudden onset/offset strongly suggests AVNRT or AVRT, while gradual acceleration/deceleration indicates sinus tachycardia 1
• Duration and frequency: Determines monitoring strategy (daily symptoms = Holter; infrequent = event recorder) 1
• Response to vagal maneuvers: Termination with Valsalva suggests re-entrant tachycardia involving AV nodal tissue 1
• Associated symptoms: Syncope, presyncope, chest pain, dyspnea, or polyuria (occurs in ~15% of SVT patients) 3, 1
• Precipitating factors: Exercise, caffeine, alcohol, medications, or recreational drugs 1, 4

Physical Examination - Key Findings

• Irregular cannon A waves and irregular variation in S1 intensity during tachycardia: Strongly suggests ventricular origin 4
• Signs of structural heart disease or thyroid dysfunction 2

12-Lead ECG - Immediate Interpretation

• Pre-excitation with regular palpitations: Presumptive AVRT—requires immediate electrophysiology referral 4
• Pre-excitation with irregular palpitations: Strongly suggests atrial fibrillation with accessory pathway—immediate EP referral due to sudden death risk 4
• Wide complex tachycardia: May represent VT or SVT with aberrancy; look for AV dissociation or fusion complexes diagnostic of VT 3
• Baseline abnormalities: May identify underlying structural disease or conduction abnormalities 2

Ambulatory ECG Monitoring Strategy

The frequency of symptoms dictates the monitoring modality:

• Daily palpitations: 24-48 hour Holter monitoring 1, 2
• Several times per week: Event recorders have superior diagnostic yield and cost-effectiveness compared to Holter 1, 5
• Less than 2 episodes per month with severe symptoms: Consider implantable loop recorder 1, 4
• Monitoring must continue until symptoms occur while wearing the device—non-diagnostic monitoring should not be considered conclusive 3, 1

Special Population: Hypertrophic Cardiomyopathy

• 24-48 hour ambulatory monitoring every 1-2 years as part of periodic follow-up 3, 2
• Extended monitoring if additional AF risk factors present (left atrial dilation, advanced age, NYHA class III-IV) 3

Laboratory Testing - Targeted Approach Only

Routine comprehensive laboratory panels are NOT useful and should be avoided. 4 Order tests only based on specific clinical suspicion:

• Thyroid-stimulating hormone: If thyroid symptoms present 4
• Complete blood count: If anemia suspected 4
• Serum electrolytes (including calcium and magnesium): If electrolyte disturbance suspected 4
• Fasting glucose or HbA1c: If hypoglycemia or diabetes suspected 4
• BNP and high-sensitivity troponin: May be considered if cardiac cause suspected, though usefulness uncertain 4

Echocardiography Indications

Order echocardiography when:

• Documented sustained SVT to exclude structural heart disease (cannot be reliably detected by physical exam alone) 1, 2
• Clinical suspicion of structural abnormalities: Valvular disease, hypertrophic cardiomyopathy, or tachycardia-mediated cardiomyopathy 1

Exercise Testing

Consider when palpitations are clearly triggered by exertion 1, 2

Immediate Specialist Referral Criteria

Refer immediately to cardiac electrophysiology for:

• All patients with Wolff-Parkinson-White syndrome (potential for lethal arrhythmias) 1
• Wide complex tachycardia of unknown origin documented on any rhythm strip 1
• Severe symptoms during palpitations (syncope, dyspnea) 1
• Narrow complex tachycardia with drug resistance or intolerance 1
• Patients desiring to be free of drug therapy 1

Empiric Management While Awaiting Monitoring

• Instruct patients in Valsalva maneuver and carotid massage to perform during episodes 1
• Stop all caffeine, alcohol, nicotine; review medications that may trigger arrhythmias 1
• Beta-blocker may be prescribed empirically only after excluding significant bradycardia (<50 bpm) 1

Critical Pitfalls to Avoid

• Never start Class I or III antiarrhythmic drugs without documented arrhythmia due to significant proarrhythmic risk 1
• Do not rely on automatic ECG analysis systems—they are unreliable and commonly suggest incorrect diagnoses 1
• Do not dismiss syncope with palpitations—this requires serious evaluation 1
• Do not order comprehensive laboratory panels routinely—only targeted testing based on clinical suspicion 4