Safety and feasibility of a midseptal implantation technique of a leadless pacemaker

The major risk of implanting a leadless pacemaker at the right ventricular (RV) apex is cardiac perforation.The purpose of this study was to describe and prospectively evaluate the safety and feasibility of a technique for midseptal implantation of the Micra leadless pacemaker.We positioned the device at the center of the cardiac silhouette in the right anterior oblique (RAO) view, toward the left in the left anterior oblique (LAO) view, and away from the sternum in the left lateral view.Among the 51 patients (mean age 81.3 ± 9.3 years; 47% men) included in the study, 29 (57%) were >80 years old, 7 (14%) had body mass index <20 kg/m2, 48 (94%) had renal dysfunction, and 33 (65%) had valvular heart disease. The implantation sites were mid and apical septum in 46 (90%) and 5 (10%) patients, respectively. Although RAO and LAO views suggested a septal location, 9 (17.6%) devices were found to be directing at the free wall in the left lateral view and required repositioning. One patient (2%) developed cardiac perforation due to contrast injection against the RV anterior wall before verification of sheath location by lateral view. Mean R-wave sensing and pacing threshold at implantation were 9.7 ± 4.0 mV and 0.61 ± 0.31 V/0.24 ms, respectively. After median follow-up of 218.7 days, the pacing threshold remained stable.In this high-risk patient cohort, midseptal implantation of a leadless pacemaker as guided by RAO, LAO, and left lateral views was achieved in 90% of patients, with a low risk of complications.