A 37-year-old woman presents to your clinic with frequent palpitations.

Comprehensive and Detailed Explanation:

The most appropriate next step for a patient with intermittent palpitations and a normal ECG is Holter monitoring (or event monitoring). This can capture and correlate symptoms with cardiac rhythm.

Toronto Notes 2023 – Cardiology, “Palpitations”:

“Holter or event monitoring is indicated when the initial ECG is normal but the patient has episodic symptoms such as palpitations.”

MCCQE1 Objectives (Cardiology > 34-2: Arrhythmia):

“Candidates must use ambulatory ECG monitoring to investigate intermittent palpitations when resting ECG is unremarkable.”

Echocardiogram (A) assesses structural issues but not rhythm. β-blockers (B) should not be started without diagnosis. Stress testing (D) is for ischemia.

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