QT interval response during standing-induced tachycardia can help in diagnosing long QT syndrome

Feb. 16, 2010( Medscape)

Summary : The QT interval response during sinus tachycardia induced by standing can serve as a useful bedside test in diagnosing long QT syndrome.

Basis for Study : The goal of this study was "to determine whether the short-lived sinus tachycardia that occurs during standing will expose changes in the QT interval that are of diagnostic value."

Detailed Summary of Study : 68 patients with long QT syndrome and 82 control subjects underwent ECGs while resting supine and then after getting up quickly. Changes in the QT interval in response to standing were then analyzed to see if they could distinguish between the groups.

Results/Body : Although the subjects' heart rate accelerated by the same amount in both groups upon standing, the average QT interval shortened in the controls but increased in the long QT patients. During maximal tachycardia the corrected QT interval increased significantly less in the control subjects than in the patients. "Receiver-operating characteristic curves showed that the test adds diagnostic value."

Sources & Other Links ; Viskin S, Postema PG, Bhuiyan ZA, Rosso R, Kalman JM, Vohra JK, Guevara-Valdivia ME, Marquez MF, Kogan E, Belhassen B, Glikson M, Strasberg B, Antzelevitch C, Wilde AA.. The response of the QT interval to the brief tachycardia provoked by standing: a bedside test for diagnosing long QT syndrome. J Am Coll Cardiol. 2010 Jan 22.


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