a Kitasato Clinical Research Center, School of Medicine, Kitasato University, Sagamihara, Kanagawa, Japan b Department of Physical Therapy, School of Health Sciences, Toyohashi SOZO University, Toyohashi, Aichi, Japan c Medical Informatics, Graduate School of Medical Sciences, Kitasato University, Sagamihara, Kanagawa, Japan d Boseione Clinic, Hatano, Kanagawa, Japan e Tsukuba International Clinical Pharmacology Clinic, Tsukuba, Ibaraki, Japan Background: Recently, a short QT interval (QT) has been thought to be a risk factor of the fatal cardiac arrhythmia as well as a prolonged QT. To avoid unexpected sudden death caused by such arrhythmia that occurred during the phase 1 clinical trials for new drugs, it is important to set beforehand the lower limit of the QT reference value and exclude the inadequate candidates for the trials. However, there was no criterion to reasonably exclude individuals with the short QT from the candidates. The purpose of this study is to set the lower limit of QT reference value in rest electrocardiograms (ECGs) in healthy young Japanese men. Methods: The rest ECGs of 1932 healthy young Japanese men (age, 20-35 years; body mass index, 18.5-25 kg/m 2 ) recorded in the screening test for the phase 1 trial in the clinic A were used for this study. The QT and R-R were measured by the computer (FCP-7431 version S; Fukuda Denshi, Redmond, WA) and verified by a cardiologist. At the first step, we divided the whole range of R-R (0.6-1.5 seconds) into 12 subgroups with the width of 75 milliseconds and located 1932 individuals (consisting of the pair of R- R vs QT) on the corresponding subgroups according to the R-R. By using the bootstrap method in each subgroup, we estimated the lower limit of the QT reference value with 95% confidence interval (CI). Finally, we approximated these 12 points representing the lower limit of the QT reference value in each subgroup by the exponential regression equation QT lower limit = α*RR β and determined its parameters. Results: The lower limit of the reference value of the QT was adequately approximated by the exponential equation QT lower limit = 373*R-R 0.3 . The range of CI widened in both extremes of R-R where the number of cases could not be sufficiently collected. Conclusion: By using the bootstrap method, we were able to approximate the lower limit of the QT reference value of healthy young Japanese men by the exponential equation QT lower limit = 373*R-R 0.3 with the 95% CI. This equation was considered to apply to the ECG screening test to exclude the individuals with short QT. doi:10.1016/j.jelectrocard.2011.09.017 The value of electrocardiographic databases—some case studies Shen Luo a , Peter Macfarlane b a Cardiac Science, WI b University of Glasgow, UK An electrocardiographic (ECG) database is the key for research, develop- ment, and evaluation of ECG methodology, criteria, automated waveform detection, and other. Study 1: The CTS (simulation) and CSE (biologic) ECG databases were used for comparison of 3 methods for manually measuring commonly used intervals and durations: (1) a single ECG cycle from lead 2, (2) an average beat derived from 10 seconds of lead 2, and (3) an online editor with electronic calipers used on a single ECG cycle across 12 simultaneously recorded leads. Three readers used the methods to annotate the databases. Results show that the third method provided the best results for CTS and stable performances for noisy situations. The mean (SD) differences for QT interval with added high-frequency noise, for example, were -0.45 (3.95), 0.86 (2.08), and 0.22 (1.08) milliseconds for the 3 methods, respectively. This study, therefore, suggests that single-beat manual measurements to annotate ECGs should not be used when an online editor incorporating 12 leads is superior. Study 2: The use of databases of normal ECGs has shown that ECG diagnostic criteria require to be sex and race based, for example, STj amplitude is higher in men than in women and higher in black men compared with white men. Criteria for ST-elevation myocardial infarction therefore need to be age, sex, and race based, for example, the upper limit of normal STj V 2 for black men is 0.318 mV but is 0.265 mV for white men aged 40 to 49 years. ST thresholds for ST- elevation myocardial infarction therefore need to be higher in black men. Study 3: A new database of pacemaker ECGs recorded at the body surface with sampling rate at 32 000 sps was developed to improve automated pacemaker stimulus detection. Pacemaker stimulus amplitudes, durations, and morphologies including a comparison with current guidelines were investi- gated first. Results showed that 56.6% of all stimuli studied, atrial or ventricular, had an amplitude or duration below the detection thresholds that manufacturers can use to claim that their equipment meets current guidelines, or the current guidelines for pacemaker stimulus detection are required to be updated. Digital pacemaker stimulus detection algorithms were developed based on the database, and their performance was evaluated as sampling rate changed. A high-speed sampling approach significantly increased the accuracy (Sens, 77.51%; PPV, 90.32% based on the 12-lead 500-sps data stream; Sens, 99.51; PPV, 100% based on the 2-lead 32 000-sps data stream). Conclusion: Databases are integral to the advancement of ECG. doi:10.1016/j.jelectrocard.2011.09.018 RTc dispersion indicate the adaptation for ICD implantation in patients with asymptomatic Brugada syndrome using a vector composition high-resolution mapping system Takashi Nakagawa, Osamu Okazaki, Sonoko Ishihara, Naohisa Hiraishi, Riri Watanabe, Munehiro Kamimura, Yuichi Tamori, Masaya Yamamoto, Shingo Ito, Yuriko Tanaka, Hisao Hara, Masao Moroi National Center for Global Health and Medicine, Tokyo Japan Recently, the indication for ICD implantation is controversial in a patient with asymptomatic Brugada syndrome (asBrS) without family history. ICD therapy is effective for the prevention from sudden cardiac death due to Brugada syndrome. We performed the evaluation in autonomic nerve activity as heart rate variability, ventricular delayed potential as late potential, and RT dispersion (RTD) using a vector composition high- resolution mapping system, simultaneously. The development of 187-channel vector-projected high-resolution ECG (DREAM-ECG; Fukuda Denshi Co, Redmond, WA) and the clinical application evaluated a risk stratification in comparison with Na-channel blocker provocation test and VT induction study on EPS. We evaluated 4 patients (3 men and a woman) with asBrS. Scattered pattern in RTD indicated for the induction of VF and can be an induction of ICD implantation in patients with asBrS. It was thought that scattered RTD may play one of the important predictive factor as the diagnosis of VF induction and repolarization heterogeneity. doi:10.1016/j.jelectrocard.2011.09.019 Estimated duration of ventricular fibrillation or simply VF quality? César Navarro a , Rebecca Di Maio a , Ian Thompson a , Andrew Howe b , John Anderson a a HeartSine Technologies, Belfast, Northern Ireland b Queen's University, Belfast, Northern Ireland Introduction: After the publication of a 3-phase time-sensitive model by Weisfeldt and Becker in 2002, research has focused on developing treatments specific to each of 3 phases of VF and means to establish its duration from the onset. There are proposed methods in the literature to estimate VF duration suggesting that early VF is in keeping with electrocardiographic morphology, exhibiting higher frequency content or higher median slopes. In addition, some studies conclude that shock outcome is related to both the initial rhythm observed before VF and VF duration itself. A perfusing rhythm before VF onset is associated with increased incidence of ROSC when compared with pulseless electrical activity and asystole. Short VF duration is associated with higher chances of ROSC. Methodology: A database of 12 patients was analyzed retrospectively. VF morphology was analyzed before every 1 of 64 shocks. Furthermore, VF morphology was analyzed before and after 17 episodes of cardiopulmonary resuscitation (CPR). 746 Poster Session 1 / Journal of Electrocardiology 44 (2011) 742–747