It is generally agreed that
It is generally agreed that a previous history of aborted cardiac arrest, syncope, presence of a spontaneous type-1 ECG, and male gender are significant predictors of further arrhythmic events [5,7,10,11,32,33].
Exercise testing Some clinical studies have reported the augmentation of ST-segment elevation and/or unmasking of type-1 ECG in the right precordial leads at early recovery periods after exercise in some patients with Brugada syndrome (Fig. 2) [34,35]. We recently investigated the prevalence and the clinical significance of the augmentation of ST-segment elevation at the early recovery phase for risk XMU-MP-1 in Brugada patients . Treadmill exercise testing was conducted in 93 patients with Brugada syndrome (22 documented VF, 35 syncope alone, and 36 asymptomatic) and 102 healthy control subjects. Augmentation of ST-segment elevation ≥0.05mV in leads V1 through V3 compared with baseline was observed at early recovery (1–4min at recovery) in 34 Brugada patients (37%) (Fig. 2A and B) but not in the remaining 59 Brugada patients (63%) (Fig. 2C) or 102 control subjects. The ST-segment elevation was usually ameliorated at peak exercise (Fig. 2A), but it was augmented even at peak exercise in some patients (Fig. 2B). The Brugada patients associated with the ST-segment augmentation at the early recovery phase had a greater risk of subsequent VF than those without (15/34 [44%] vs. 10/59 [17%], P=0.004) during 76±38 months of follow up. Multivariate Cox regression analysis showed that augmentation of ST-segment elevation at the early recovery phase was a significant and independent predictor for cardiac events (P=0.007), especially in patients with a history of syncope alone (6/12 [50%] vs. 3/23 [13%]) and in asymptomatic patients (3/15 [20%] vs. 0/21 [0%]). Thus, augmentation of ST-segment elevation at the early recovery phase during exercise testing was specific in patients with Brugada syndrome and can be a predictor of poor prognosis, especially in patients with syncope alone and in asymptomatic patients.
> Signal-averaged ECG Frequency of late potentials (LP) in the signal-averaged ECG has been reported to be higher in patients with Brugada syndrome than in control subjects. In a single-center study, Ikeda et al. reported a sensitivity of 89%, specificity of 50%, positive predictive value of 70%, and negative predictive value of 77% for LP for risk stratification of life-threatening events .
Fragmented QRS Morita and colleagues reported that fragmented QRS recorded in the standard 12-lead ECGs (with 0- to 150-Hz filters) was more often observed in Brugada patients with VF episodes than in those with syncope or in asymptomatic patients . They also reported that patients who had fragmented QRS frequently experienced recurrence of syncope due to VF within 4 years of the first episode of syncope or VF. More recently, in the PRELUDE study, Priori et al. reported that fragmented QRS was an independent predictor for arrhythmic events in Brugada patients without a history of VF .
Programmed electrical stimulation The usefulness of programmed electrical stimulation (PES) to stratify risk of subsequent arrhythmic events has long been controversial between the Brugada registry and other registries [5,7,10,11,32,33]. To fill this gap, Priori organized a multicenter prospective registry (PRELUDE study) with a uniform protocol in patients with Brugada syndrome without a history of VF . They suggested that arrhythmia inducibility during PES was not a predictor of subsequent events during follow-up but that a ventricular effective refractory period <200ms was an independent predictor for arrhythmic events. Makimoto et al. recently reported a significance of the number of extrastimuli at PES as a predictor of arrhythmic events in patients with type-1 Brugada ECG . Multivariate Cox regression demonstrated that the induction of VF with up to double extrastimuli was an independent predictor. Therefore, they suggested that up to double extrastimuli were adequate at PES to stratify risk in patients with Brugada syndrome.