Brugada syndrome in Thailand: Three decades of progress

Abstract

Our group began investigating the cause of sudden unexplained death syndrome in Thailand in 1994 and found that among sudden unexplained death syndrome patients, the Brugada phenotype was ubiquitous. Following this important observation, Brugada syndrome (BrS) became our main research focus and has galvanized our collaboration with several global prominent scientists over the past 30 years. Through this collaborative research, we made major progress toward better understanding of the syndrome and gained knowledge in genetic background, pathophysiology, and new management. Two consensus reports were published to help define diagnostic criteria, risk stratification, and management of BrS patients. In this review, we share our experiences and progress of our research and development of our program that was designed to identify the cause of sudden death, understand pathophysiology of the syndrome, and develop effective and safe management and therapy of BrS patients. Although our work in Thailand was challenging at the beginning, it later blossomed into a multicollaborative research enterprise that has produced several important findings that have shed light on the pathophysiology of BrS and development of a new effective treatment modality, catheter ablation.

Keywords: Ablation; Brugada syndrome; Ion channelopathy; Sudden cardiac death; Sudden unexplained death syndrome; Ventricular fibrillation.

Figure 1

An example of how higher lead positioning can unmask a Brugada electrocardiography pattern. Note that the Brugada electrocardiography pattern is absent in the standard lead positioning at the fourth intercostal space (ICS) but is present in V2 at the third ICS and present in both V1 and V2 at the second ICS.

Figure 2

An example of how ajmaline, sodium-channel blocker, unmasks the Brugada electrocardiography pattern in conjunction with higher intercostal space (ICS) lead positioning (see text for details).

Figure 3

A comparison of the effects of ajmaline vs procainamide for unmasking Brugada intercostal space (ICS) pattern (see text for detail). ICS, intercostal space.

Figure 4

(Top) Kaplan-Meier survival curves for the 2 treatment arms (implantable cardioverter-defibrillator vs β-blocker (propranolol). The primary endpoint was mortality. Modified from Nademanee et al with permission. (Bottom) Cumulative proportion of ventricular fibrillation/death occurrence using the composite endpoints of recurrent ventricular tachycardia/ventricular fibrillation (VF) or cardiac arrest from which the patient was resuscitated or death.

Figure 5

Kaplan-Meier survival curves for 2 treatment arms (implantable cardioverter-defibrillator [ICD] vs no ICD) in asymptomatic Brugada syndrome patients. The primary endpoint was mortality.

Figure 6

A composite picture of the CARTO-merge maps showing the cardiac computed tomography that is merged with the electroanatomic maps of the right ventricular outflow tract (RVOT) epicardium. The double annotation map (A2-A1), shown on the left, illustrates the scale of abnormal prolonged duration of the ventricular electrograms in the anterior RVOT as displayed in the color-coded area; the blue represents the longest duration (>160 ms) during sinus rhythm. The right inset displays the electrograms recorded from the NaviStar-ThermoCool catheter at the site of the anterior aspect of the RVOT epicardium (arrow). Red dots represent ablation points. Note that the duration of the electrograms in this area is quite prolonged (>160 ms) and low voltage (0.84 mV), is fractionated, and has prolonged duration (183 ms) and delayed depolarization beyond the end of the lead II-QRS complex (150 ms). M1= unipolar distal; M1M2 = bipolar distal; M2 = unipolar of the second electrode; M3M4 = bipolar proximal.