Background

The Micra® leadless pacemaker (LP) has been safely implemented into clinical routine. Lead induced tricuspid valve (TCV) disturbance should be unlikely after LP implantation. However, sole right-ventricular (RV) VVI pacing potentially impairs RV function (Fx) and might cause tricuspid valve regurgitation (TCVR). Lately, few smaller studies reported of TCVR after LP implantation. Data in this field is rare, inconsistent and includes the omitted Nanostim® system.

Objective

This substudy of a largest German LP registry sought to investigate whether LP pacing has an impact on RV-Fx and TCV-Fx. This could be relevant in establishing LP as an alternative to traditional VVI-systems, which may cause TCVR and impair RV-Fx.

Methods

Between 06/2016 and 09/2019 140 consecutive pts underwent TPS implantation in two centers. Data of echocardiographic Follow-Up (FU) was collected from 23 (16%) pts (12 women [52%], age 79±9 years) in one center. Investigated parameters were left ventricular function, RV-Fx (TAPSE and basal RV), TCVR (mild, moderate, severe), systolic pulmonary artery pressure (SPAP) and right atrial area (RA) before and after LP.

Results

All 23 pts underwent successful LP implantation. In 5 patients (22%) extraction of conventional devices was performed previous to LP implantation. All other pts were de-novo LP implantations. Mean percentage of RV pacing demand was 54%±41% during FU.

After a median FU of 411 days there were no differences in LV-Fx (53%±9% vs. 54%±8%; p=0.63). Furthermore, RV-Fx evaluated by TAPSE (19mm±4mm vs. 19mm±5mm; p=0.77), basal RV (40mm±8mm vs. 39mm±7mm; p=0.22) and SPAP (42mmHg±19mmHg vs. 38mmHg±16 mmHg; p=0.10) showed no differences before and after LP pacing. After LP implantation following changes of degree in TCVR were observed: Six (23%) pts showed milder TCVR than before (severe to mild or moderate, moderate to mild), 14 (61%) showed no difference and 3 (13%, all de-novo) worsened regarding TCVR (mild to moderate or severe, moderate to severe). All of these were functional TCVR due to RV and LV dilatation with concomitant mitral regurgitation and LV-Fx.

Conclusion

In this substudy of the largest German LP registry implantation of the Micra LP with a high pacing demand was neither associated with impairment of LV- or RVFx, nor TCVR. Further prospective studies comparing conventional VVI with LP systems are ongoing to underline potential benefits of LPs.