Key result
Microelectrode mapping yields ~1 mV higher voltages than standard bipolar mapping, identifying smaller scar regions.
Why the study?
Assessment of ventricular myocardial substrate critically depends on mapping electrode size, wavefront orientation, and interelectrode distance, prompting evaluation of microelectrode mapping during VT catheter ablation.
Does microelectrode mapping improve the identification of viable myocytes and substrate assessment compared to standard bipolar mapping in patients undergoing catheter ablation for ventricular tachycardia?
Observational (n=21)
Yes
Does microelectrode mapping improve the identification of viable myocytes and substrate assessment compared to standard bipolar mapping in patients undergoing catheter ablation for ventricular tachycardia?
Effect estimate: Difference 0.98 mV (95% CI 0.93-1.04)
p-value: p=<0.01
Microelectrode mapping is more sensitive than standard bipolar mapping for identifying viable myocytes in sinus rhythm, resulting in smaller measured scar areas and potentially facilitating target recognition for VT ablation.
May refine VT substrate mapping; hypothesis-generating for clinical outcomes pending prospective validation.
Introduction The assessment of the ventricular myocardial substrate critically depends on the size of mapping electrodes, their orientation with respect to wavefront propagation, and interelectrode distance. We conducted a dual‐center study to evaluate the impact of microelectrode mapping in patients undergoing catheter ablation (CA) of ventricular tachycardia (VT). Methods We included 21 consecutive patients (median age, 68 [12], 95% male) with structural heart disease undergoing CA for electrical storm ( n = 14) or recurrent VT ( n = 7) using the QDOT Micro catheter and a multipolar catheter (PentaRay, n = 9). The associations of peak‐to‐peak maximum standard bipolar (BV c ) and minibipolar (PentaRay, BV p ) with microbipolar (BV μMax ) voltages were respectively tested in sinus rhythm with mixed effect models. Furthermore, we compared the features of standard bipolar (BE) and microbipolar (μBE) electrograms in sinus rhythm at sites of termination with radiofrequency energy. Results BV μMax was moderately associated with both BV c ( β = .85, p < .01) and BV p ( β = .56, p < .01). BV μMax was 0.98 (95% CI: 0.93−1.04, p < .01) mV larger than corresponding BV c , and 0.27 (95% CI: 0.16−0.37, p < .01) mV larger than matching BVp in sinus rhythm, with higher percentage differences in low voltage regions, leading to smaller endocardial dense scar (2.3 [2.7] vs. 12.1 [17] cm 2 , p < .01) and border zone (3.2 [7.4] vs. 4.8 [20.1] cm 2 , p = .03) regions in microbipolar maps compared to standard bipolar maps. Late potentials areas were nonsignificantly greater in microelectrode maps, compared to standard electrode maps. At sites of VT termination ( n = 14), μBE were of higher amplitude (0.9 [0.8] vs. 0.4 [0.2] mV, p < .01), longer duration (117 [66] vs. 74 [38] ms, p < .01), and with greater number of peaks (4 [2] vs. 2 [1], p < .01) in sinus rhythm compared to BE. Conclusion microelectrode mapping is more sensitive than standard bipolar mapping in the identification of viable myocytes in SR, and may facilitate recognition of targets for CA.
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Russo et al. (2023) conducted an observational in Ventricular tachycardia in structural heart disease (n=21). Microelectrode mapping (QDOT Micro catheter) vs. Standard bipolar mapping and minibipolar mapping was evaluated on Difference in voltage amplitude between microbipolar and standard bipolar mapping in sinus rhythm (Difference 0.98 mV, 95% CI 0.93-1.04, p=<0.01). Microelectrode mapping yielded voltages 0.98 mV larger than standard bipolar mapping (95% CI 0.93-1.04; p<0.01), leading to smaller identified endocardial dense scar and border zone regions.
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