Identification of the potential LQT2 carriers by using the caviar method

The congenital Long QT Syndrome (LQTS) is an inherited disorder of ventricular repolarization that predisposes affected individuals to sudden death. The analysis of conventional ECG may be misleading, and we need non invasive markers to identify more accurately patients with rhese conditions. In the LQn syndrome, the fast-deluyed rectifier current Ikr is altered and leads tu a prolonged Action Potential Duration (APD) in midmyocardial areas that in turn translates to a prolonged QT interval and a widened T-wave. The aim of this work was to find new ECG parameters which can be used to identify LQ72 curriers in a large population. The study population was composed of 67 normal healthy subjects and I1 known carriers of U HERG mutation flour dierenr mutations and four families). For each subject a 12-lead digital ECG was recorded and analyzed by using the spatiotemporal CAVIAR method. With only one single CAVIAR measurement we could correctly classify 93.6% of the cases. This measurement, called UDIR, represents the diference in orientation between the T wave and the beginning of QRS. Its values are significantly higher in the Le72 patients (mGD±58.5° /spl plusmn14.5°) than in the normal population (m&SD±21.6° ±14.6°)with a pvalue< 1OE-9. This study demonstrates that it could be possible to identlB potential LQn carriers by analyzing spatiotemporal ECG waveform patterns of a conventional 12 -lead ECG.