Relationship between ST-segment morphology and conduction disturbances detected by signal-averaged electrocardiography in Brugada syndrome

Abstract

Background: Although arrhythmogenesis of Brugada syndrome is still unknown, it has been reported to be associated with conduction disturbances. Two ST-segment morphologies (coved and saddle-back patterns) have been described in this syndrome. No study has sought to determine which morphology has stronger conduction disturbances, thereby associating with life-threatening events.

Methods: Forty-six patients who presented the Brugada-type ECG with either of a characteristic coved (n = 25) or saddle-back (n = 21) pattern of ST-segment morphology underwent signal-averaged ECG (SAECG). SAECG parameters, and the history of life-threatening events defined as syncope or aborted sudden death, were compared between groups.

Results: Although filtered QRS duration did not differ between groups, the incidence of late potentials in the coved group was higher than in the saddle-back group (22 patients (88%) versus 4 patients (19%); P < 0.01), showing lower RMS40 and longer LAS40. Life-threatening events occurred in 17 patients (68%) in the coved group and 7 patients (33%) in the saddle-back group (P = 0.02).

Conclusion: The coved pattern of ST segment was more closely related to conduction disturbances than the saddle-back pattern in patients with Brugada-type ECG. Life-threatening events were more common in patients with the coved ST-segment elevation. Conduction disturbances in the coved pattern of ST segment may reflect a substrate of arrhythmogenesis in Brugada syndrome.

Figure 1

(A) Twelve‐lead ECG during sinus rhythm showing a Brugada‐type ECG classified as coved group. (B) Twelve‐lead ECG during sinus rhythm showing a Brugada‐type ECG classified as saddle‐back group.

Figure 2

(A) Electrocardiographic tracings in leads V₁ to V₃ and the SAECG for the same patient as shown in Figure 1A. The f‐QRS is 114 ms. The late potentials, represented by the shaded area, are positive, showing an RMS₄₀ of 14.8 μV, and an LAS₄₀ of 43 ms. (B) Electrocardiographic tracings in leads V₁ to V₃ and the SAECG for the same patient as shown in Figure 1B. The f‐QRS is 92 ms. The late potentials, represented by the shaded area, are negative, showing an RMS₄₀ of 25.2 μV, and an LAS₄₀ of 34 ms.