OBJECTIVES: The purpose of this study was to test for a genetic component to risk for acquired long QT syndrome (LQTS). BACKGROUND: Many drugs prolong the QT interval, and some patients develop excessive QT prolongation and occasionally torsades de pointes-the acquired LQTS. Similarities between the acquired and congenital forms of the long QT syndrome suggest genetic factors modulate susceptibility. METHODS: Intravenous quinidine was administered to 14 relatives of patients who safely tolerated chronic therapy with a QT-prolonging drug (control relatives) and 12 relatives of patients who developed acquired LQTS, and ECG intervals between groups were compared. RESULTS: Baseline QT and heart-rate corrected QT (QTc) were similar (QT/QTc: 394 +/- 28/410 +/- 20 ms vs 395 +/- 24/418 +/- 20 ms; control vs acquired LQTS) and prolonged equally in the two groups. The interval from the peak to the end of the T wave, an index of transmural dispersion of repolarization, prolonged significantly with quinidine in acquired LQTS relatives (63 +/- 17 to 83 +/- 18 ms, P = .017) but not in control relatives (66 +/- 19 to 71 +/- 18 ms, P = 0.648). In addition, the baseline peak to end of the T wave as a fraction of the QT interval was similar in both groups but was longer in acquired LQTS relatives after quinidine (16.3 +/- 3.5% and 19.5 +/- 3.9% in control and acquired LQTS relatives, respectively, P = .042). CONCLUSIONS: First-degree relatives of patients with acquired long QT syndrome have greater drug-induced prolongation of terminal repolarization compared to control relatives, supporting a genetic predisposition to acquired long QT syndrome.
OBJECTIVES: The purpose of this study was to test for a genetic component to risk for acquired long QT syndrome (LQTS). BACKGROUND: Many drugs prolong the QT interval, and some patients develop excessive QT prolongation and occasionally torsades de pointes-the acquired LQTS. Similarities between the acquired and congenital forms of the long QT syndrome suggest genetic factors modulate susceptibility. METHODS: Intravenous quinidine was administered to 14 relatives of patients who safely tolerated chronic therapy with a QT-prolonging drug (control relatives) and 12 relatives of patients who developed acquired LQTS, and ECG intervals between groups were compared. RESULTS: Baseline QT and heart-rate corrected QT (QTc) were similar (QT/QTc: 394 +/- 28/410 +/- 20 ms vs 395 +/- 24/418 +/- 20 ms; control vs acquired LQTS) and prolonged equally in the two groups. The interval from the peak to the end of the T wave, an index of transmural dispersion of repolarization, prolonged significantly with quinidine in acquired LQTS relatives (63 +/- 17 to 83 +/- 18 ms, P = .017) but not in control relatives (66 +/- 19 to 71 +/- 18 ms, P = 0.648). In addition, the baseline peak to end of the T wave as a fraction of the QT interval was similar in both groups but was longer in acquired LQTS relatives after quinidine (16.3 +/- 3.5% and 19.5 +/- 3.9% in control and acquired LQTS relatives, respectively, P = .042). CONCLUSIONS: First-degree relatives of patients with acquired long QT syndrome have greater drug-induced prolongation of terminal repolarization compared to control relatives, supporting a genetic predisposition to acquired long QT syndrome.
Authors: David G Strauss; Jose Vicente; Lars Johannesen; Ksenia Blinova; Jay W Mason; Peter Weeke; Elijah R Behr; Dan M Roden; Ray Woosley; Gulum Kosova; Michael A Rosenberg; Christopher Newton-Cheh Journal: Circulation Date: 2017-02-17 Impact factor: 29.690
Authors: Saagar Mahida; Andrew J Hogarth; Campbell Cowan; Muzahir H Tayebjee; Lee N Graham; Christopher B Pepper Journal: J Interv Card Electrophysiol Date: 2013-03-21 Impact factor: 1.900
Authors: Daniel Scherer; Katharina von Löwenstern; Edgar Zitron; Eberhard P Scholz; Ramona Bloehs; Sven Kathöfer; Dierk Thomas; Alexander Bauer; Hugo A Katus; Christoph A Karle; Claudia Kiesecker Journal: Naunyn Schmiedebergs Arch Pharmacol Date: 2008-05-06 Impact factor: 3.000