Jonathan P Piccini1, Kurt Stromberg2, Kevin P Jackson3, Verla Laager2, Gabor Z Duray4, Mikhael El-Chami5, Christopher R Ellis6, John Hummel7, D Randy Jones8, Robert C Kowal9, Calambur Narasimhan10, Razali Omar11, Philippe Ritter12, Paul R Roberts13, Kyoko Soejima14, Shu Zhang15, Dwight Reynolds16. 1. Duke University Medical Center, Durham, North Carolina. Electronic address: jonathan.piccini@duke.edu. 2. Medtronic plc, Mounds View, Minnesota. 3. Duke University Medical Center, Durham, North Carolina. 4. Clinical Electrophysiology, Department of Cardiology, Medical Centre, Hungarian Defence Forces, Budapest, Hungary. 5. Emory University Hospital, Atlanta, Georgia. 6. Vanderbilt University Medical Center, Nashville, Tennessee. 7. Ohio State University, Columbus, Ohio. 8. Providence Health & Services, Portland, Oregon. 9. BHVH at Baylor University Medical Center, Dallas, Texas. 10. CARE Hospitals, CARE Foundation, Hyderabad India. 11. Electrophysiology and Pacing Unit, National Heart Institute, Kuala Lumpur, Malaysia. 12. Hôpital Cardiologique du Haut-Lévêque, CHU Bordeaux, Université Bordeaux, IHU LIRYC, Bordeaux, France. 13. University of Southampton, Southampton, United Kingdom. 14. Department of Cardiology, Kyorin University Hospital, Tokyo, Japan. 15. Clinical EP Lab and Arrhythmia Center, Fuwai Hospital, Beijing, China. 16. Cardiovascular Section, University of Oklahoma Health Sciences Center, OU Medical Center, Oklahoma City, Oklahoma.
Abstract
BACKGROUND: Device repositioning during Micra leadless pacemaker implantation may be required to achieve optimal pacing thresholds. OBJECTIVE: The purpose of this study was to describe the natural history of acute elevated Micra vs traditional transvenous lead thresholds. METHODS: 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. RESULTS: 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 < .001) in both cohorts. Micra patients with high and very high thresholds decreased significantly (P < .01) by 1 month, with 87% and 85% having 6-month thresholds lower than the implant value. However, when the capture threshold at implant was >2 V, only 18.2% had a threshold of ≤1 V at 6 months and 45.5% had a capture threshold of >2 V. CONCLUSIONS: 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.
BACKGROUND: Device repositioning during Micra leadless pacemaker implantation may be required to achieve optimal pacing thresholds. OBJECTIVE: The purpose of this study was to describe the natural history of acute elevated Micra vs traditional transvenous lead thresholds. METHODS: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. RESULTS: Of the 711 Micrapatients, 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 < .001) in both cohorts. Micrapatients with high and very high thresholds decreased significantly (P < .01) by 1 month, with 87% and 85% having 6-month thresholds lower than the implant value. However, when the capture threshold at implant was >2 V, only 18.2% had a threshold of ≤1 V at 6 months and 45.5% had a capture threshold of >2 V. CONCLUSIONS: Pacing thresholds in most Micrapatients with elevated thresholds decrease after implant. Micra device repositioning may not be necessary if the pacing threshold is ≤2 V.
Authors: Anthony C McCanta; Gira S Morchi; Froilan Tuozo; Farhouch Berdjis; Joanne P Starr; Anjan S Batra Journal: HeartRhythm Case Rep Date: 2018-08-01