Elevated pacing thresholds in Micra leadless pacemakers decreased significantly over 6 months (87% of high and 85% of very high thresholds improved), suggesting repositioning is unnecessary if ≤2 V.
Cohort (n=1,249)
Yes
Does the pacing threshold of Micra leadless pacemakers with elevated thresholds at implantation decrease over 6 months compared to traditional transvenous leads?
p-value: p=<.001
BackgroundDevice repositioning during Micra leadless pacemaker implantation may be required to achieve optimal pacing thresholds.ObjectiveThe purpose of this study was to describe the natural history of acute elevated Micra vs traditional transvenous lead thresholds.MethodsMicra study VVI patients with threshold data (at 0.24 ms) at implant (n = 711) were compared with Capture study patients with de novo transvenous leads at 0.4 ms (n = 538). In both cohorts, high thresholds were defined as >1.0 V and very high as >1.5 V. Change in pacing threshold (0–6 months) with high (1.0 to ≤1.5 V) or very high (>1.5 V) thresholds were compared using the Wilcoxon signed-rank test.ResultsOf the 711 Micra patients, 83 (11.7%) had an implant threshold of >1.0 V at 0.24 ms. Of the 538 Capture patients, 50 (9.3%) had an implant threshold of >1.0 V at 0.40 ms. There were no significant differences in patient characteristics between those with and without an implant threshold of >1.0 V, with the exception of left ventricular ejection fraction in the Capture cohort (high vs low thresholds, 53% vs 58%; P = .011). Patients with an implant threshold of >1.0 V decreased significantly (P 2 V, only 18.2% had a threshold of ≤1 V at 6 months and 45.5% had a capture threshold of >2 V.ConclusionsPacing thresholds in most Micra patients with elevated thresholds decrease after implant. Micra device repositioning may not be necessary if the pacing threshold is ≤2 V. Device repositioning during Micra leadless pacemaker implantation may be required to achieve optimal pacing thresholds. The purpose of this study was to describe the natural history of acute elevated Micra vs traditional transvenous lead thresholds. Micra study VVI patients with threshold data (at 0.24 ms) at implant (n = 711) were compared with Capture study patients with de novo transvenous leads at 0.4 ms (n = 538). In both cohorts, high thresholds were defined as >1.0 V and very high as >1.5 V. Change in pacing threshold (0–6 months) with high (1.0 to ≤1.5 V) or very high (>1.5 V) thresholds were compared using the Wilcoxon signed-rank test. Of the 711 Micra patients, 83 (11.7%) had an implant threshold of >1.0 V at 0.24 ms. Of the 538 Capture patients, 50 (9.3%) had an implant threshold of >1.0 V at 0.40 ms. There were no significant differences in patient characteristics between those with and without an implant threshold of >1.0 V, with the exception of left ventricular ejection fraction in the Capture cohort (high vs low thresholds, 53% vs 58%; P = .011). Patients with an implant threshold of >1.0 V decreased significantly (P 2 V, only 18.2% had a threshold of ≤1 V at 6 months and 45.5% had a capture threshold of >2 V. Pacing thresholds in most Micra patients with elevated thresholds decrease after implant. Micra device repositioning may not be necessary if the pacing threshold is ≤2 V.
Piccini et al. (Thu,) conducted a cohort in Pacemaker implantation (n=1,249). Micra leadless pacemaker vs. Traditional transvenous leads was evaluated on Change in pacing threshold (0-6 months) with high (1.0 to <=1.5 V) or very high (>1.5 V) thresholds (p=<.001). Elevated pacing thresholds in Micra leadless pacemakers decreased significantly over 6 months (87% of high and 85% of very high thresholds improved), suggesting repositioning is unnecessary if ≤2 V.
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