An Intraoperative Fluoroscopic Predictor of Successful Micra Implantation on the Right Ventricular Mid-Septum

The Micra transcatheter pacing system has been adopted globally. However, the procedural parameters for safe Micra implantation on the ventricular wall, particularly in the mid-septum, remain unknown. This study aimed to identify the predictors of Micra implantation on the ventricular mid-septum.

We retrospectively analyzed patients who underwent Micra implantation and had computed tomography (CT) after implantation to confirm the device position. Patients were classified into mid-septum and non-mid-septum groups based on CT findings. To explore predictors associated with mid-septal implantation, fluoroscopic parameters in the standard left anterior oblique (LAO) view were evaluated during implantation, including the presence of an α-loop shape of the delivery catheter and the angle between the axis of the device cup and the tangent of the ventricular septum (angle θ). Logistic regression analysis was performed to identify predictors of mid-septal Micra implantation.

Of 119 patients who underwent Micra implantation, 59 had CT confirmation. Among them, 31 (52.5%) had mid-septal, 18 (30.5%) apical septal, and 10 (17.0%) free wall implantation. Since no cases involved basal septal positioning, the non-mid-septum group consisted of apical septal and free wall implantations. The angle θ was significantly larger and the α-loop shape of the catheter was more frequent in the mid-septum group. However, multivariable analysis identified only the α-loop shape as an independent predictor of mid-septal implantation (adjusted odds ratio, 5.10; 95% CI, 1.40-20.7; p = 0.016).

An α-loop shape of the delivery catheter may serve as a practical fluoroscopic marker for successful mid-septal Micra implantation.