A 32-year-old woman presents with recurrent episodes of sudden-onset palpitations, chest tightness, and fear of dying lasting 15–20 minutes, occurring unpredictably 2–3 times per week for the past 3 months. She reports no chest pain, dyspnea, or syncope during attacks. Physical examination and resting ECG are normal. Which investigation is most appropriate to exclude cardiac etiology before confirming panic disorder?

Explanation

## Investigation of Choice: 24-Hour Holter Monitoring ### Clinical Context This patient presents with classic panic attack symptoms: sudden onset, brief duration (15–20 min), autonomic hyperarousal (palpitations, chest tightness), and catastrophic cognitions (fear of dying). The normal resting ECG does not exclude paroxysmal arrhythmias. ### Why Holter Monitoring is the Answer **Key Point:** 24-hour Holter monitoring is the investigation of choice to detect paroxysmal arrhythmias (SVT, atrial fibrillation, premature beats) that may mimic panic attacks and occur unpredictably during daily activities. **High-Yield:** Holter monitoring captures heart rhythm over 24 hours, correlating symptoms with ECG findings—essential for ruling out arrhythmia-induced panic-like symptoms before attributing them to a primary psychiatric disorder. **Clinical Pearl:** Patients with panic disorder often report palpitations as a cardinal symptom; Holter monitoring provides objective evidence that symptoms are NOT cardiac in origin, which itself can be therapeutic (reassurance). ### Comparison of Cardiac Investigations | Investigation | Indication | Sensitivity for Panic Mimic | Yield in This Case | |---|---|---|---| | **24-h Holter** | Paroxysmal arrhythmias, symptom correlation | High for episodic SVT, AF, ectopy | **BEST** — captures unpredictable events | | Transthoracic echo | Structural heart disease (valve, cardiomyopathy) | Low — no structural disease suspected | Not indicated; echo is normal in panic | | Exercise stress test | Inducible ischemia, exercise-triggered arrhythmia | Moderate — but attacks are unpredictable, not exertional | Not indicated; no exertional pattern | | Coronary angiography | Significant coronary stenosis | High but invasive | Contraindicated; no evidence of ACS or ischemia | **Mnemonic: HOLTER for Panic Screening — H = Hourly capture, O = Occult arrhythmias, L = Long duration (24 h), T = Temporal correlation, E = Exclude cardiac, R = Reassure patient.** ### Algorithm for Panic vs. Cardiac Chest Pain ```mermaid flowchart TD A["Sudden-onset palpitations + chest tightness"]:::outcome --> B{"Resting ECG normal?"}:::decision B -->|Yes| C{"Symptoms unpredictable, brief, with catastrophic thoughts?"}:::decision B -->|No| D["Acute ECG abnormality — manage as cardiac"]:::urgent C -->|Yes| E["Order 24-h Holter to exclude paroxysmal arrhythmia"]:::action C -->|No| F["Consider structural disease — echo, stress test"]:::action E --> G{"Holter shows arrhythmia?"}:::decision G -->|Yes| H["Treat arrhythmia; reassess for panic"]:::outcome G -->|No| I["Confirm panic disorder diagnosis"]:::outcome ``` ### Key Diagnostic Principle In panic disorder, the goal is **exclusion of medical mimics** before confirming a psychiatric diagnosis. Holter monitoring is the most efficient, non-invasive, and cost-effective test to rule out paroxysmal cardiac arrhythmias that could present identically to panic attacks.