P6-32

S312 p⫽0.049). With regard to cardiac mortality a WMI with normal value showed a negative predictive value of 95%. Discussion: The data presented clearly shows that in our ICD Pts with coronary artery disease the WMI was able to predict the inducibility of VT during electrophysiological testing. Furthermore, Pts, who had a low risk for cardiac mortality were identified successfully. The prediction seems to be comparable with studies of T-wave-alternans on P with coronary artery disease. Whereas, the evaluation of a pathological WMI has to be explored in further studies. P6-32 PREDICTION OF LONG-TERM EFFICACY OF CATHETER ABLATION BY SIGNAL-AVERAGED ELECTROCARDIOGRAM AND 24-HOUR HOLTER ELECTROCARDIOGRAM IN ARRHYTHMOGENIC RIGHT VENTRICULAR CARDIOMYOPATHY PATIENTS WITH SUSTAINED VENTRICULAR TACHYCARDIA Kenji Obayashi, MD, Katsuya Kajimoto, MD, Dai Yumino, MD, Tetsuyuki Manaka, MD, Kohei Tanizaki, MD, Morio Shoda, MD, PhD, Nobuhisa Hagiwara, MD and Hiroshi Kasanuki, MD. Tokyo Women’s Medical University, Tokyo, Japan. Purpose: The purpose of our study is to determine whether a long-term efficacy of catheter ablation (CA) for arrhythmogenic right ventricular cardiomyopathy (ARVC) patients (pts) with sustained ventricular tachycardia (VT) can be predicted by non-invasive examination, such as signalaveraged ECG (SAECG) and 24-hour Holter ECG. Methods: In 51 ARVC pts with sustained VT in our hospital, 44 pts who underwent CA were investigated. Three variables in SAECG were quantitatively evaluated before CA: filtered QRS duration (f-QRS), duration of low amplitude signal⬍40␮V (LAS), and root mean square voltage for the last 40ms (RMS). Moreover, arrhythmias on baseline Holter ECG, such as premature ventricular beats (PVB) and nonsustained VT, were evaluated before CA. These variables were compared between pts with and without recurrence of VT during a mean follow-up of 10.4 yrs. Results: There were no significant differences in f-QRS and LAS between pts with (N⫽15) and without (N⫽29) recurrence of VT. However, regarding RMS, there was a significant difference between these two groups (3.7⫾2.5 vs. 15.0⫾19.7 ␮V, p⫽0.03). Frequent PVB on Holter ECG showed a significant difference between these two groups (1767⫾1532 vs. 784⫾1245, p⫽0.03) although there was no significant difference in nonsustained VT. In addition, a criteria of RMS ⬎5.0 ␮V, which was calculated by ROC analysis, gave a sensitivity of 80%, a specificity of 68% and a total accuracy of 72 % for predicting the long-term efficacy of CA. The probability of recurrence of VT showed a significant difference between pts with RMS ⬎5.0 ␮V and ⱕ5.0 ␮V (Figure). Conclusions: The quantitative analysis of SAECG and Holter ECG before CA is useful in predicting the long-term efficacy of CA for ARVC pts with sustained VT.

P6-33 COMBINATION OF HIGH-RESOLUTION MAGNETOCARDIOGRAPHY AND ELECTROCARDIOGRAPHY IN PREDICTION OF ARRHYTHMIC EVENTS AFTER MYOCARDIAL INFARCTION AND CARDIAC DYSFUNCTION

Heart Rhythm, Vol 3, No 5, May Supplement 2006 Petri Korhonen, MD, Terhi Husa, MD, Ilkka Tierala, MD, Heikki Va¨a¨na¨nen, BSc, Markku Ma¨kija¨rvi, MD, Toivo Katila, PhD and Lauri Toivonen, MD. Helsinki University Central Hospital, Helsinki, Finland and Helsinki University of Technology, Espoo, Finland. Background: Both increased fragmentation in magnetocardiographic (MCG) QRS complexes and prolonged QRS duration (QRSd) in highresolution (HR) ECG have shown association to arrhythmic events and sudden cardiac death after myocardial infarction (MI). We studied how the combination of these methods predicts major arrhythmic events ( sudden cardiac death or sustained ventricular arrhythmia) after MI and cardiac dysfunction. Methods: Patients (n⫽158) with acute MI and cardiac dysfunction had high-resolution MCG and HR-ECG registered at hospital discharge. After signal-averaging of 150-250 cardiac cycles intra-QRS fragmentation (FRA) in MCG was computed and previously defined cut-point value of 57.5 was used as the criterion for abnormality. For QRSd in HR-ECG, 114 ms was the cut-point value for abnormality. Results: During a mean follow-up of 50 months (range 1-70) 18 patients had a major arrhythmic event (11 sustained ventricular arrhythmias and 7 sudden cardiac deaths). Both FRA in MCG (log-rank 12.6, P ⬍ 0.001) and QRSd in HR-ECG (log-rank 8.0, P ⬍ 0.005) were significant predictors of MAEs. Also in multivariate analysis including several clinical variables both FRA and QRSd had independent predictive value. The combination of the parameters (FRA ⬎ 57.5 and QRSd ⬎ 114 ms) did not outperform the prediction of FRA alone (log-rank 12.2, P ⬍ 0.001). Positive predictive accuracy (PPA) of FRA was superior to QRSd whereas negative predictive accuracies (NPA) were similar (Table). The parameter combination did not increase significantly PPA or NPA. Conclusion: Increased intra-QRS fragmentation in MCG exhibiting inhomogeneous fragmented depolarization predicts major arrhythmic events after MI. Combining MCG with QRS duration in HR-ECG does not increase the prediction derived from MCG alone. Table FRA

PPA 23%

NPA 96%

QRSd Combined criterion

PPA 19% PPA 25%

NPA 96% NPA 95%

P6-34 HOLTER-DERIVED QT VARIABLES IN RISK STRATIFICATION FOR SUDDEN CARDIAC DEATH IN PATIENTS WITH CHRONIC HEART FAILURE WITH PRESERVED SYSTOLIC FUNCTION Eiichi Watanabe, MD, PhD, Kenji Yasui, MD, PhD, Itsuo Kodama, MD, PhD, Yoshihiro Sobue, MD, Hiroshi Takeuchi, BSc, Toshiaki Terasawa, BSc and Hitoshi Hishida, MD, PhD. Fujita Health University, Toyoake, Japan, Department of Bioinformation Analysis, Nagoya, Japan, Nagoya University, Nagoya, Japan, Fujita Health University School of Medicine, Toyoake, Japan and Suzuken Co., Ltd., Nagoya, Japan. Background: Since the sudden cardiac death (SCD) occurs frequent in patients with chronic heart failure (CHF), this group of patients is of primary concern when identifying candidates for the prevention of SCD with implantable defibrillators. The mechanism of SCD may be attributed to interplay of factors representing the autonomic regulation of the heart, reduced left ventricular ejection fraction (LVEF), and electrical instability. We evaluated the prognostic significance of circadian variations in RR and QT intervals and QT dynamicity (QT/RR slope) in CHF patients with preserved systolic function as compared with heart rate turbulence, pump function, renal function and neurohumoral factor. Methods and Results: We prospectively enrolled 121 patients with worsening CHF in sinus rhythm with QRS ⬍ 120 ms (age, 67 ⫾ 14 years, mean ⫾ SD; range, 34-87 years). The prevalence of ischemic and non-