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Omar Abdul Razakjr, Yeo Wee Tiong, Seow Swee Chong and Singh Devinder
American Heart Hospital Journal Volume 8 No.1

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Long QT syndrome (LQTS) is a rare potentially life-threatening condition. Physicians must remain vigilant and consider LQTS as apossible etiology in patients with a history of syncope. Prolongation of the QT interval on electrocardiogram (ECG) is an essentialcomponent for the diagnosis of LQTS, despite the limitations of this technique. Experience of analyzing the ECG and calculatingcorrected QTc still remain relevant and are the mainstay diagnostic tools. Often, the first sign of the problem is observed after careful evaluation of the resting ECG for the hallmark of the disorder. Unfortunately, more than 60% of physicians—even cardiologists—have been known to misinterpret the QT interval on ECG. The cases discussed in this article highlight the variable clinical presentation of prolonged QT interval and the need to be highly vigilant in clinical evaluation.

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The term 'torsades de pointes,' coined in 1966 todescribe the peculiar appearance of a ventriculartachycardia occurring in an elderly woman withheart block, is often translated as a 'twisting of the points,'referring to the beat-to-beat changes in the QRS axis.¹Congenital syndromes involving QT-interval prolongationand syncope or sudden death were first described in the late1950s and early 1960s.^1-3 However, the congenital long QTsyndrome (LQTS) is rare, while the acquired LQTS,particularly associated with use of various drugs, is common.The few electrocardiographically documented cases ofsyncope or sudden death in patients with a congenital LQTShave been characterized by torsades de pointes.⁴ Because ofthe malignant clinical features of LQTS and the need for aprompt diagnosis that leads to effective treatment, everyphysician should be aware of its varied clinical presentationand also be able to recognize LQTS on electrocardiogram(ECG). Often, the first sign of the problem is observed oncareful evaluation of the resting ECG for the hallmark of thedisorder. Unfortunately, more than 60% of physicians—even cardiologists— have been known to misinterpret theQT interval on ECG.5 In this article we present three cases ofprolonged QT interval presented to National University Hospital, Singapore, with the aim of increasing awarenessand knowledge about LQTS within the general medicalcommunity. These cases highlight the variable clinicalpresentation of prolonged QT interval and the need to behighly vigilant in clinical evaluation.

Clinical Cases
The first case is an octogenarian woman hospitalized forfrequent falls due to syncope and knee pain under theorthopaedics team. She has a past medical history ofhypertension and paroxysmal atrial fibrillation. Hermedications include tramadol hydrochloride, hydrochlorthiazide,and aspirin. Clinical examination wasotherwise unremarkable except for the clinical findings ofosteoarthritis of the bilateral knee joints. Laboratoryinvestigation showed hypokalemia (serum potassium2.9mmol/l), which was attributed to hydrochlorthiazide. Theelectrocardiogram showed sinus rhythm and prolonged QTcof 592 milliseconds, but this abnormality went unrecognizedby the attending physician (see Figure 1).

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