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New model quantifies cardiac arrest risk in Brugada syndrome

JACC: Clinical Electrophysiology
Reuters Health - 03/11/2020 - A new risk stratification model for patients with Brugada syndrome (BrS) is based on four risk factors for ventricular arrhythmias/sudden cardiac death (VA/SCD) and can inform the need for an implantable cardioverter defibrillator (ICD), researchers say.

"Identifying high-risk cases prior to a cardiac arrest remains controversial and we wanted to develop a simple 'bedside' risk score to help clinicians," Dr. Pier Lambiase of University College London, UK, told Reuters Health by email. "The score enables doctors to provide a meaningful percentage risk of cardiac arrest at five years according to patient age to enable informed decision making and targeted ICD implantation. Further validation is planned in independent patient cohorts."

As reported in the Journal of the American College of Cardiology: Clinical Electrophysiology, Dr. Lambiase and colleagues evaluated the role of 16 proposed clinical or electrocardiogram (ECG) markers in predicting VA/SCD in 1,110 BrS patients from eight countries (mean age 51.8; 71.8% male). During a mean follow-up of 5.33 years, 114 patients had VA/SCD (10.3%), for an annual event rate of 1.5%.

Four of the 16 risk factors were associated with a higher risk of VA/SCD: probable arrhythmia-related syncope (PAR; hazard ratio, 3.71), spontaneous type 1 ECG (HR, 3.80), early repolarization (HR, 3.42), and a type 1 Brugada ECG pattern in peripheral leads (HR, 2.33).

The risk score model incorporating the four factors had a sensitivity of 71.2% and a specificity of 80.2% for predicting VA/SCD at five years. Calibration plots showed a mean prediction error of 1.2%.

To validate this risk score, the team conducted an out-of-sample cross-validation by country. The four risk factors yielded consistent results across all cross-validation samples.

The authors note, "PAR syncope and a spontaneous type 1 Brugada ECG pattern remain independent predictors of VA/SCD, compatible with the findings of numerous BrS studies. Interestingly, the presence of ER (early repolarization) and a type 1 Brugada ECG pattern in peripheral leads, which has previously only been assessed in a few studies, were shown to be independent predictors of VA/SCD in this cohort."

Currently, the score can be read from the graph and a table in the paper, Dr. Lambiase noted, and an online calculator is in development.

Dr. Chirag Barbhaiya, an electrophysiologist at NYU Langone's Heart Rhythm Center in New York City, commented by email, "Of the four risk factors they identify, two are currently commonly used - type 1 Brugada ECG pattern, and probable arrhythmia-related syncope. The other two risk factors - early repolarization, and type 1 Brugada pattern in peripheral leads - have only been previously reported in smaller studies, so the robustness of the risk associated with these factors is new, and this paper will prompt greater attention to these factors both in clinical care and for further investigation."

"The authors recommend using a cutoff of 5% risk of arrhythmia over five years to determine need for ICD implantation," he noted. "In their model, presence of a type 1 Brugada pattern alone is associated with a 5.9% risk over five years. Multiple prior studies have shown patients with type 1 Brugada pattern and no other risk factors to be at low risk of arrhythmia; thus, the model should be interpreted with caution in these patients."

"Although a minority of patients underwent programmed stimulation in this study, the lack of predictive value even in univariate analysis is notable," he added. "The strength of recommendation for programmed stimulation in the guidelines is weak, and this data further weakens that recommendation."

By Marilynn Larkin

SOURCE: https://bit.ly/2I0QEEg Journal of the American College of Cardiology: Clinical Electrophysiology, online October 28, 2020.

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