Management of untreatable ventricular arrhythmias during pharmacologic challenges with sodium channel blockers for suspected Brugada syndrome

Abstract

Pharmacologic challenge with sodium channel blockers is part of the diagnostic workout in patients with suspected Brugada syndrome. The test is overall considered safe but both ajmaline and flecainide detain well known pro-arrhythmic properties. Moreover, the treatment of patients with life-threatening arrhythmias during these diagnostic procedures is not well defined. Current consensus guidelines suggest to adopt cautious protocols interrupting the sodium channel blockers as soon as any ECG alteration appears. Nevertheless, the risk of life-threatening arrhythmias persists, even adopting a safe and cautious protocol and in absence of major arrhythmic risk factors. The authors revise the main published case studies of sodium channel blockers challenge in adults and in children, and summarize three cases of untreatable ventricular arrhythmias discussing their management. In particular, the role of advanced cardiopulmonary resuscitation with extra-corporeal membrane oxygenation is stressed as it can reveal to be the only reliable lifesaving facility in prolonged cardiac arrest.

Type‐I Paradox of Brugada Syndrome

“…VF occurs in <1% of all tests and <2% of all positive tests,18 but may become incessant 17. With this call for caution in mind, we present our take‐home message from the study by Ueoka, regarding patient subgroups that could potentially benefit from the well‐described diagnostic aspects, and newly described prognostic value, of the test.…”

“…Anyone wishing to perform (or undergo) a SCB test should first become familiar with the publication by Poli on the risk of refractory VF that can be triggered by the test 17. VF occurs in <1% of all tests and <2% of all positive tests,18 but may become incessant 17.…”

“…Furthermore, in this study only 2% of patients were female and only 1 was younger than 18 years. This is important because the test appears to be not only less predictive,21 but also less safe for women and children 17…”

Prognostic Significance of the Sodium Channel Blocker Test in Patients With Brugada Syndrome

“…Female sex is a possible risk for arrhythmic events during an SCB test 6. We could not determine sex risk of the SCB test in this study because we performed the test in only 5 female patients (2%).…”

“…The extents of PQ prolongation and QRS widening during the SCB test can be a clue for the existence of SCN5A mutation 2, 3, 4. Although the SCB test is essential for diagnosis in non–type 1 patients, an unexpected response to administration of an SCB, such as atrioventricular block or ventricular tachyarrhythmias (VTAs), occasionally emerges in some patients 5, 6…”