Characteristic Features of QRST Integral Mapping in Patients With High Risk Brugada Syndrome

Abstract

rugada syndrome (BS) is associated with a high risk of sudden cardiac death secondary to life-threatening arrhythmias; that is, ventricular tachycardia and fibrillation (VT/VF) in young and otherwise healthy adults. 1-4 ECG abnormalities constitute the hallmark of BS and include a coved or saddleback-type ST-segment elevation in the right precordial leads (V1-3) accompanied by T wave alterations, with or without some degree of right bundle branch block in the absence of identifiable structural cardiac abnormalities. However, there are a substantial number of patients who show Brugada-type ECGs but do not develop fatal arrhythmias. Therefore, it is important in the clinical practice to discriminate patients with the Brugada-type resting ECG who are at a high risk for lifethreatening ventricular arrhythmias from those at low risk. However, at present there is not a non-invasive method of risk stratification.Among the approaches to detect patients at risk of lifethreatening ventricular arrhythmias, QRST integral mapping is of particular interest. The spatial distributions of the QRST integrals reflect an anatomic and electrophysiological substrate for fatal ventricular arrhythmias. 5-10 It has Circulation Journal Vol. 71, January 2007 been shown that QRST integral mapping is capable of assessing the vulnerability to ventricular arrhythmias in various heart diseases. [11][12][13][14] Accordingly, we investigated whether patients with Brugada-type resting ECGs and life-threatening arrhythmias can be non-invasively characterized using QRST integral mapping. If so, QRST integral mapping could be a new non-invasive screening method to discriminate between high and low risk patients with regard to life-threatening arrhythmias. In the present study, QRST isointegral maps and QRST integral departure maps were created in patients with Brugada-type resting ECGs with at least 1 of the following: aborted sudden death, a history of spontaneous sustained VT/VF or programmed electrical stimulation (PES)-inducible sustained VT/VF. These findings were compared with those of Brugada-type ECG patients who had not experienced such cardiac events. Methods Study GroupsThis retrospective study included 24 consecutive patients with Brugada-type resting ECGs, all of whom underwent body-surface QRST isointegral mapping at Kurume University Hospital from January 1997 to August 2005. The enrolled patients had no evidence of structural abnormalities of the heart based upon cardiac echocardiograms, coronary angiograms, and right and left ventriculograms. None of the patients enrolled in this study was taking antiarrhythmic drugs. The present study was approved by the Ethical Committee for Clinical Research of Kurume University, and all subjects gave written informed consent.The Brugada-type ECGs were recognized as having type- Characteristic Features of QRST Integral Mapping in Patients With High Risk Brugada SyndromeMasaaki Kanahara, MSc; Hisashi Kai, MD*; Koji Toyomasu, MD**; Teruhisa Yoshida, MD*; Tatsuro Hiraki, MD*; Kimitaka Sagawa, MD...