Which tests should be included in the workup of long QT syndrome (LQTS)?

Updated: Nov 29, 2017
  • Author: Ali A Sovari, MD, FACP, FACC; Chief Editor: Mikhael F El-Chami, MD  more...
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Routinely check serum levels of potassium (and sometimes magnesium) and thyroid function in patients who present with QT prolongation after arrhythmic events, to eliminate secondary reasons for repolarization abnormalities.

Analysis of repolarization duration (QTc) and morphology on a patient's electrocardiogram (ECG) and on the ECGs of the patient's relatives frequently leads to an accurate diagnosis.

Hinterseer et al found that increased short-term variability of the QT interval—ie, STV(QT)—in symptomatic patients with congenital long QT syndrome (LQTS) could be a useful noninvasive additive marker for diagnostic screening to bridge the gap while waiting for results of genetic testing. [19]  This study is the first in humans to observe this association.

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