Brugada type 1 electrocardiographic (ECG) pattern occurs in 0.2% of Filipinos. A knowledge gap exists on the natural course of asymptomatic patients with Brugada type 1 ECG pattern. Most studies that reported cohort event rates were taken from hospitals or referral centers. This is the first cohort from an entire country where the subjects were selected randomly. The objective of this study was to describe the frequency of cardiac events at 4 and 6 years of 7 patients with Brugada type 1 ECG pattern of 3,907 patients previously screened from the general population of the Philippines during the National Nutrition and Health Survey. Personal interviews at year 4 using a structured questionnaire were conducted by 1 of the investigators. Occurrences of major (syncope, seizure, unexplained accidents, sudden death) and minor events in subjects and their first- and second-degree relatives were elicited. Six-year follow-up by text messaging was conducted to ascertain vital status and occurrence of cardiac events. All 7 patients with Brugada type 1 ECG pattern were men. Three of the 7 initially asymptomatic subjects (43%, 95 confidence interval 6 to 80) developed a major cardiac event by the fourth year. Those with events were younger than those without events. All 7 were alive by the sixth year. No additional events were noted between the fourth and sixth years. In conclusion, cardiac events are considerable in initially asymptomatic Filipinos with Brugada type 1 ECG pattern.
Brugada type 1 electrocardiographic (ECG) pattern occurs frequently in Filipinos. During the 2003 Philippine National Nutrition and Health Survey (NNHES), 7 of 3,907 subjects (0.2%) from the general population selected in a stratified randomized sampling based on age and geographic region were found to have Brugada type 1 ECG pattern. All subjects were asymptomatic on initial diagnosis. The prognostic significance of this Brugada type 1 ECG sign in initially asymptomatic patients is unknown. In symptomatic patients (syncope, seizure, or sudden cardiac death) this ECG marker identifies a high risk of symptom recurrence or sudden cardiac death, but its significance in those who are asymptomatic is uncertain. Conflicting data exist on event rates in asymptomatic patients with Brugada ECG pattern. Priori et al reported no events in this group, whereas Brugada et al reported a 27% 2-year event rate. This study describes the frequency of cardiac events at 4 and 6 years in the 7 initially asymptomatic patients identified during the 2003 NNHES. Major (sudden death, syncope, seizure, presyncope) and minor (e.g., moaning during sleep but patients easily aroused) events are described.
Methods
The 7 patients with Brugada type 1 ECG pattern (2-mm J-point elevation and ≥1-mm convex ST-segment elevation in leads V 1 and V 2 ) randomly identified from the 3,907 screened from the general population during the 2003 NNHES were initially contacted by a third party to obtain preliminary consent. This was done to protect patients’ privacy. After receipt of this preliminary consent by the third party, formal informed consent was obtained by the investigators.
A visit was done 4 years (2007) after the initial ECG identification. During the visit a validated questionnaire focusing on identifying major and minor cardiac events, identifying family history of similar events, and excluding alternative causes for sudden death was administered to the individual by 1 of the investigators (G.J.). Additional questions not included in the questionnaire were allowed for clarification of points. A 12-lead ECG recording was then obtained.
A follow-up on the sixth year was performed by telephone interview and/or text messaging to ascertain whether any more cardiac events had occurred.
No statistical analysis was performed. Event rate was reported as mean with its 95% confidence interval (CI).
Results
There were 7 patients with Brugada type 1 ECG pattern of 3,907 chosen randomly from the general population in the Philippines during the 2003 NNHES. All were men with mean age of 50 years (37 to 62). Three subjects were <50 years of age. All were asymptomatic at the time of ECG identification, reporting no previous episodes of syncope, presyncope, seizure, unexplained accidents, palpitations, chest pains or shortness of breath before ECG identification in 2003. Five of these 7 were from Luzon, the largest island in the Philippines, and 2 were from Mindanao, the southern tip of the archipelago.
All 7 were alive at follow-up visits 4 years (2007) and 6 years (2009) after initial ECG diagnosis. Repeat 12-lead electrocardiograms in the fourth year still showed Brugada type 1 ECG sign in all subjects. Of the 7 subjects, 3 had a major cardiac event (syncope, seizure, prolonged nonarousability), representing possible spontaneously terminating ventricular arrhythmia. This represents an event rate of 43% (95% CI 6 to 80). The 3 who reported major cardiac events were in their third or fourth decade of life. This is in contrast to the other 4 patients with no reported events who were in their fifth and sixth decades of life. The 3 who reported events had excellent functional capacity, denied angina, and had no known cardiac condition. Only 1 had a known cardiac risk factor (hypertension). These 3 subjects had brief spontaneously terminating major events (syncope and near syncope) during daytime activity (farming, sweeping, 1 while seated); 2 of these 3 also had nocturnal events described as labored breathing, profuse sweating, moaning, and prolonged nonarousability during sleep. The 2 were eventually aroused; however, 1 was brought to the emergency room due to difficulty in arousing him. Upon reaching the emergency room he was fully conscious, although sweating profusely ( Table 1 ). Only 1 of the 3 subjects with events had a first-degree relative (father) who had sudden cardiac death. However, the father was 71 years of at time of death.
| Age (years) ⁎ /Sex | Place of Residence | Major Event † | Minor Event ‡ | First-Degree Relative With Sudden Cardiac Death | Second-Degree Relative With Sudden Cardiac Death |
|---|---|---|---|---|---|
| 49/M | Sarangani | 2 | 0 | 0 | 0 |
| 32/M | Samal, Davao | 4 | 0 | 0 | 0 |
| 37/M | La Trinidad, Benguet | 2 | 1 | Father at 71 years of age | 0 |
| 54/M | Binangonan, Rizal | 0 | 0 | None | 0 |
| 55/M | Bulacan | 0 | 0 | Brother at 38 years of age | 2 nephews (30, 42 years of age) |
| 61/M | Isabela | 0 | 0 | Brother at 51 years of age | 2 nephews (32, 40 years of age) |
| 62/M | Bolinao, Pangasinan | 0 | 0 | 0 | 0 |
† Unexplained death, successful resuscitation, near death requiring hospitalization, unexplained accidents requiring confinement, syncope or near syncope that can be attributed to nonsustained ventricular tachycardia, or witnessed nocturnal agonal respiration.
‡ Being awakened from sleep spontaneously or by vigorous stimulation, with symptoms of severe distress or impending doom.
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