Advantages of the QDOT MICRO Catheter in Finding Conduction Gaps in Pulmonary Vein Isolation Compared With the Conventional 3.5-mm Tip Electrode.

backgroundPulmonary vein isolation (PVI) remains a cornerstone treatment for atrial fibrillation; however, residual conduction gaps often hinder first-pass success and contribute to late reconnection, leading to arrhythmia recurrence. The QDOT MICRO catheter (Biosense Webster Inc., CA, USA) is equipped with three microelectrodes at its tip. Their small size and short inter-electrode spacing allow for a more detailed recording of intracardiac potentials. This study evaluated the utility of the QDOT MICRO catheter in detecting conduction gaps during PVI.

methodsForty-four gaps in 40 patients undergoing initial PVI were analyzed by comparing electrograms recorded using microelectrodes and conventional 3.5-mm tip electrodes.

resultsAt the gap sites, the local electrogram voltage recorded by microelectrodes was significantly higher than that by 3.5-mm tip electrodes (median, 0.449 vs. 0.195 mV, p < 0.001), representing a 2.3-fold amplification. The prevalence of fragmented potentials at the gap sites was significantly higher with microelectrodes than with 3.5-mm tip electrodes (61% vs. 30%, p < 0.001). In 36% of gaps, fragmented potentials were detected with microelectrodes, whereas the 3.5-mm electrodes recorded nonfragmented signals, contributing to accurate gap detection. In 11% of gaps, the amplitude was extremely low with 3.5-mm tip electrodes [median 0.107 (IQR 0.088-0.112) mV], rendering the interpretation of local electrogram challenging. However, microelectrodes amplified the signal [median 0.215 (IQR 0.176-0.283) mV], allowing for accurate identification and interpretation.

conclusionMicroelectrodes enhance the detection and characterization of conduction gaps, particularly under low-voltage or in scarred tissue, thereby improving ablation accuracy.