Evaluation of Palpitations
Initial Clinical Assessment
Begin by determining whether the palpitations are regular or irregular, as this single distinction fundamentally changes your entire diagnostic approach and differential diagnosis. 1, 2
Critical History Elements
Onset and termination pattern: Sudden onset with sudden termination strongly suggests AVNRT or AVRT, particularly in younger patients 1, 2. Gradual acceleration and deceleration indicates sinus tachycardia, often triggered by infection, volume loss, caffeine, nicotine, or medications 1, 2
Response to vagal maneuvers: Termination by Valsalva or carotid massage suggests re-entrant tachycardia involving AV nodal tissue 1, 2
Associated symptoms:
- Syncope occurs in approximately 15% of SVT patients and may indicate WPW syndrome with rapid AF conduction, valvular aortic stenosis, hypertrophic cardiomyopathy, or ventricular arrhythmias 1
- Polyuria suggests SVT due to atrial natriuretic peptide release from atrial contraction against closed AV valves 1, 2
- Presyncope, chest discomfort, or dyspnea warrant urgent evaluation 1, 2
Duration and frequency: Document number of episodes, duration, and triggers to guide monitoring strategy 1, 2
Family history: Specifically ask about unexpected sudden cardiac death in young relatives, which raises concern for inherited arrhythmia syndromes 1
Medication review: Assess for Class IA/IC antiarrhythmics, antihypertensives, phenothiazines, tricyclics, and recreational drugs 1, 2
Physical Examination Priorities
Look for irregular cannon A waves and irregular variation in S1 intensity during tachycardia, which strongly suggests ventricular origin 2
Assess for signs of congestive heart failure or cardiac outflow obstruction, as these indicate higher risk of adverse outcomes 1
Perform carotid sinus massage (if no recent TIA/stroke or significant carotid stenosis) in elderly patients with palpitations during neck turning 1, 3
Immediate Diagnostic Testing
12-Lead ECG (Mandatory)
Obtain a 12-lead ECG immediately in all patients with palpitations to identify rhythm, look for pre-excitation, determine if regular versus irregular, and assess for structural abnormalities 1, 2, 3. Do not rely on automatic ECG interpretation systems—they are unreliable and commonly suggest incorrect diagnoses 2.
Key ECG findings requiring immediate action:
- Pre-excitation with regular palpitations history = presumptive AVRT → immediate electrophysiology referral 2
- Pre-excitation with irregular palpitations = AF with accessory pathway → immediate EP referral due to sudden death risk 2
- Wide complex tachycardia = possible VT → immediate EP referral 2
- QT prolongation suggests inherited long QT syndrome 1
- Evidence of prior MI, ventricular hypertrophy, or conduction abnormalities predicts higher risk 1
Targeted Laboratory Testing
Do not order routine comprehensive laboratory panels—they have extremely low diagnostic yield and are not recommended. 2, 3 Instead, order targeted tests based on clinical suspicion:
- TSH: Essential to exclude hyperthyroidism 2, 3
- Electrolytes (including calcium and magnesium): Only if history suggests electrolyte disturbance 2, 3
- Complete blood count: Only if anemia suspected 3
- BNP and high-sensitivity troponin: May be considered if cardiac cause suspected, though usefulness is uncertain 3
- Hemoglobin/hematocrit or stool guaiac: Only if acute blood loss suspected 1
- Pregnancy test: In women of childbearing potential 1
Ambulatory ECG Monitoring Strategy
The choice of monitoring depends entirely on symptom frequency:
Daily Palpitations
Several Times Per Week
- Event recorder or loop recorder (superior diagnostic yield and more cost-effective than Holter) 2, 4
Less Than 2 Episodes Per Month
- Implantable loop recorder, especially if symptoms are severe or associated with hemodynamic instability 2, 3
Critical pitfall: Monitoring must continue until symptoms occur while wearing the device—non-diagnostic monitoring should not be considered conclusive 2
Echocardiography Indications
Order echocardiography when:
- Documented sustained SVT to exclude structural heart disease (cannot be reliably detected by physical examination alone) 2
- Clinical suspicion of valvular aortic stenosis, hypertrophic cardiomyopathy, or tachycardia-mediated cardiomyopathy 1, 2
- Abnormal ECG or physical examination suggesting structural disease 3
Mandatory Immediate Electrophysiology Referral
Refer immediately to cardiac electrophysiology for:
- All patients with Wolff-Parkinson-White syndrome (due to potential for lethal arrhythmias) 2
- Wide complex tachycardia of unknown origin documented on any rhythm strip 2
- Severe symptoms during palpitations (syncope, near-syncope, severe dyspnea) 2
- Pre-excitation on ECG with any palpitation history 2
- Drug-resistant or drug-intolerant narrow complex tachycardia 2
- Patients desiring to be free of drug therapy 2
Empiric Management While Awaiting Monitoring
Beta-blockers may be prescribed empirically while awaiting monitoring results, but only after excluding significant bradycardia (<50 bpm) 2, 5. Propranolol 40-80 mg three times daily has established efficacy for SVT and atrial fibrillation rate control 5.
Critical pitfall: Never start Class I or III antiarrhythmic drugs without documented arrhythmia due to significant proarrhythmic risk 2
Special Considerations
Tachycardia-Mediated Cardiomyopathy
- SVT persisting for weeks to months with fast ventricular response can cause reversible cardiomyopathy, emphasizing the importance of timely diagnosis 1, 2
Hypertrophic Cardiomyopathy Patients
- Require 24-48 hour ambulatory monitoring every 1-2 years as part of periodic follow-up 2
- Extended monitoring recommended if additional AF risk factors present (left atrial dilatation, advanced age, NYHA class III-IV) 2
Exercise-Induced Palpitations
- Consider exercise stress testing if palpitations are clearly triggered by exertion 2