Morphological identification of brugada type 1 pattern using loop recorder: a feasibility study

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Abstract Introduction The presence of spontaneous type 1 Brugada pattern (BP1) is associated with an elevated risk of arrhythmic events. Diagnosis of this condition is often underestimated due to its intermittent nature. While periodic ambulatory ECG monitoring can distinguish patients with pharmacologically induced patterns from those with spontaneous patterns, the diagnostic capabilities of this method are limited. Implantable cardiac monitors (ICM), designed to continuously record heart rhythm, may offer higher sensitivity in detecting patients with intermittent patterns. However, the ICM's ability to morphologically identify the ST segment elevation associated with BP1 remains uncharted. Purpose This study aimed to assess the ICM's capacity to morphologically identify the ST segment elevation associated with BP1. Methods We enrolled all patients who underwent ajmaline testing (AT) between November 2022 and September 2023 in our centre. For positive patients, the external simulator of a loop recorder was utilized to evaluate four positions (I-II left intercostal space at a 45° tilt, II-III left intercostal space at a 45° tilt, II-III right parasternal intercostal space, and II-III left parasternal intercostal space). These positions were selected to capture the trace with the most significant ST segment elevation at the J point during the peak positivity of the ECG during the ajmaline test. Measurements from the recorded traces were acquired using dedicated software. Results Out of 50 patients, 21 (male-to-female ratio 1.62:1, mean age 43.4±13.1 years) had a positive AT result. Seventeen patients exhibited ST segment elevation in the simulator trace during the highest ajmaline dose. Among these patients, the optimal recording position was in the I-II left intercostal space at a 45° tilt in 66.7% of cases. The median ST segment elevation recorded by the simulator was 0.9 mm (interquartile range 0.6-1.1 mm). Notably, there was no observed correlation between the extent of ST segment elevation in the ECG and that recorded by the simulator trace (Pearson linear coefficient = 0.09). Conclusions ICM may offer the potential to record BP1, a finding that holds significant diagnostic and prognostic implications for asymptomatic patients with pharmacologically induced BP1. Further research is needed to develop useful programming algorithms for the automatic recording of this pattern.