INAPPROPRIATELY SHORTER QT INTERVAL AT SLOWERHEART RATE CAN DIFFERENTIATE PATIENTS WITHIDIOPATHIC VENTRICULAR FIBLLATION FROMASYMPTOMATIC BRUGADA SYNDROME

摘要

The electrocardiographic parameters predicting occurrence of ventricular fibrillation (VF) episode in asymptomatic subjects with Brugada-like ECG is still unknown. The aim of this study was to clarify the characteristics of QT-RR relation in idiopathic VF in comparison with asymptomatic subjects having Brugada-like ECG. Methods: The study group consisted of 9 males (age 47 +- 10yo) with I VF (6 Brugada type and 3 non-Brugada type) who had had recent episodes of VF and 9 asymptomatic healthy males with Brugada-like ECG (age 49 +- 15yo). The relation between QT and RR interval was analyzed from 24-hour Holter ECG using automatic measurement system. From QT-RR linear regression lines, both QT intervals extrapolated to RR of 0.6 sec (QT(0.6)) and 1.5 sec (QT(1.5)) were determined. Results: The slope of QT-RR regression line was lower in IVF than in asymptomatic subjects with Brugada-like ECG (0.09 +-0.02 vs. 0.13 +-0.03, p<0.005). QT(1.5) was shorter in IVF than in asymptomatic subjects (0.43 +-0.02sec vs. 0.46 +-0.02sec, p<0.01) but QT(0.6) did not differ between them (0.38 +-0.02sec vs. 0.39 +-0.02sec, ns). Conclusion: Short QT intervals at slower heart rate in idiopathic VF patients suggest that not only ST-segment elevation but also lower slope of QT-RR relation may play an important role for the occurrence of VF episode at night.