Brugada Syndrome: Subcutanous ICDs Linked to Misfires

Patients with Brugada syndrome are at risk of inappropriate shocks from subcutaneous implantable cardioverter-defibrillator (sICD) during changes in their electrocardiogram (ECG) pattern, investigators found.

Morphology analysis failed in 24% of patients upon development of a type 1 pattern during ajmaline testing, all due to more pronounced T-waves, reported Louise R.A. Olde Nordkamp, MD, PhD, of Academic Medical Center in Amsterdam, the Netherlands, and colleagues in the August 9, 2016 issue of the Journal of the American College of Cardiology.

All patients with this ajmaline-evoked ECG morphology had appropriate morphology analysis at baseline.

"These patients are accordingly at risk for inappropriate shocks," they wrote. "Sensing might be particularly difficult in Brugada syndrome patients because of the dynamic nature of the ECG morphology."

"We therefore recommend that in the presence of a type-1 Brugada Syndrome ECG after subcutaneous ICD implantation, for example, during fever or during an additional ajmaline test, all three sensing vectors should be evaluated, and the best suitable sensing vector should be programmed."

For their investigation, Olde Nordkamp and colleagues included 88 consecutive patients who were screened for Brugada syndrome at two European centers, 21 of whom had a type 1 ECG. The study population had a mean age of 49 years; 47% were men.

"Over time and during fever, the ECG of Brugada syndrome patients may change from a type 3 or 2 Brugada ECG to type 1 Brugada ECG. Type 1 Brugada syndrome ECG, which is characterized by prominent ST-T segment changes, is particularly relevant because it is strongly linked to the occurrence of arrhythmias," Olde Nordkamp's group suggested.

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