Unmasking Long QT Syndrome in the Emergency Department: A Case Report

Long QT syndrome (LQTS) is an uncommon disorder that can lead to potentially life-threatening dysrhythmias. LQTS can be genetic, acquired, or both.

A 44-year-old female with well-controlled hypertension and asthma presented with chest tightness. An initial electrocardiogram yielded a normal corrected QT interval of 423 milliseconds (ms) (normal <480 ms in females). Albuterol was administered and induced agitation, tremulousness, and tachycardia. Follow-up electrocardiograms demonstrated extreme prolongation of the corrected QT interval to 633 ms and morphology change of the T wave. Lab values were later notable for hypokalemia and hypomagnesemia, attributable to a recently started thiazide diuretic. The patient was ultimately diagnosed with congenital LQTS after initial unmasking by albuterol in the emergency department.

LQTS can be unmasked or exacerbated by electrolyte abnormalities and QT prolonging medications.