Initial Workup for Sudden Tachycardia and Panic Symptoms
The initial workup for a patient presenting with sudden tachycardia and panic symptoms should include a 12-lead ECG, basic biochemistry panel, thyroid function tests, and cardiac troponin measurement to distinguish between cardiac and non-cardiac causes. 1, 2
Immediate Assessment
Clinical Evaluation
Obtain detailed symptom characteristics:
- Onset (sudden vs. gradual)
- Duration (paroxysmal vs. sustained)
- Associated symptoms (chest pain, dyspnea, lightheadedness, syncope)
- Triggers (exercise, stress, meals, sleep)
- Relieving factors (vagal maneuvers, rest, position changes)
Physical examination focusing on:
- Vital signs (heart rate, blood pressure, respiratory rate)
- Cardiovascular exam (irregular pulse, jugular venous pulsations, heart sounds)
- Signs of hyperthyroidism (tremor, exophthalmos)
- Signs of heart failure (pulmonary rales, peripheral edema)
Essential Diagnostic Tests
12-lead ECG (during symptoms if possible) 2
- To identify arrhythmia pattern (narrow vs. wide complex)
- Look for pre-excitation patterns suggesting accessory pathways
- Document rate, regularity, and P wave morphology
- Complete blood count (to detect anemia)
- Basic metabolic panel (electrolytes, renal function)
- Cardiac troponin (to rule out myocardial injury)
- Thyroid function tests (TSH, free T4)
- Glycemic status (HbA1c and/or fasting glucose)
Continuous cardiac monitoring during evaluation
- Multi-lead ECG monitoring to capture paroxysmal events
Differential Diagnosis Considerations
Cardiac Causes
- Supraventricular tachycardia (SVT)
- AVNRT (AV nodal reentrant tachycardia)
- AVRT (AV reentrant tachycardia)
- Atrial tachycardia
- Atrial fibrillation/flutter
- Sinus tachycardia (appropriate or inappropriate)
- Ventricular tachycardia (less common but important to exclude)
Non-Cardiac Causes
- Panic disorder (diagnosis of exclusion)
- Thyroid disorders
- Anemia
- Dehydration/hypovolemia
- Medication effects or withdrawal
- Substance use (caffeine, alcohol, stimulants)
Important Clinical Considerations
Cardiac vs. Panic Disorder
Studies show that up to 67% of patients with paroxysmal SVT meet diagnostic criteria for panic disorder, and SVT remains unrecognized in approximately 55% of patients after initial medical evaluation 3. Women are more likely than men to have PSVT symptoms attributed to psychiatric causes (65% vs. 32%) 3.
Monitoring Strategies
- Event monitors are significantly more effective than Holter monitors for detecting paroxysmal arrhythmias (47% vs. 9% detection rate) 3
- Consider extended monitoring for patients with recurrent symptoms
Warning Signs Requiring Urgent Evaluation
- Syncope or pre-syncope
- Chest pain
- Persistent tachycardia despite rest
- Signs of hemodynamic instability
- Abnormal cardiac biomarkers
Follow-up Recommendations
For patients with documented arrhythmias:
- Referral to cardiology/electrophysiology
- Consider stress testing to evaluate for underlying coronary disease
- Echocardiogram to assess cardiac structure and function
For patients with negative initial workup but persistent symptoms:
- Extended cardiac monitoring (event recorder, patch monitor)
- Consider tilt table testing if orthostatic symptoms are present
Common Pitfalls to Avoid
- Misattributing symptoms to anxiety without adequate cardiac evaluation
- Focusing only on heart rate and missing paroxysmal arrhythmias
- Using inadequate monitoring techniques (Holter instead of event monitoring)
- Failing to recognize pre-excitation on resting ECG
- Overlooking thyroid dysfunction as a potential cause
By following this systematic approach, clinicians can effectively differentiate between cardiac arrhythmias and panic disorder, ensuring appropriate treatment and avoiding misdiagnosis of potentially serious cardiac conditions.