Electrocardiogram predictors of leadless pacemaker implantation in the right ventricular free wall

Abstract

Abstract Background Leadless pacemakers (LLP) carry the potential risk of cardiac injury, especially when implanted in the free wall of the right ventricle. Purpose To investigate the ECG criteria for distinguishing free wall implantation of LLP, further clarification is needed. Methods We conducted a retrospective study involving 17 patients who underwent LLP implantation, followed by chest computed tomography to confirm the implantation site. Patients were categorized into three groups based on the location of implantation (septum [Sep], apex [Apex], and free wall [FW]), and we compared the morphology of the 12-lead ECG during LLP pacing. Results Among the implantation sites, nine were in the Sep (52.9%), five in the Apex (29.4%), and three in the FW (15.8%). In terms of pacing QRS morphology, the FW group exhibited significantly longer QRS duration (Sep: 145.6±15.2 vs. Apex: 161.6±3.6 vs. FW: 175.3±16.6, P<0.01), a notched QRS complex in lead III (Sep: 0.0% vs. Apex: 0.0% vs. FW: 100.0%, P<0.01), and a shorter peak deflection index (PDI) in lead V1 (Sep: 0.59±0.07 vs. Apex: 0.55±0.06 vs. FW: 0.40±0.02, P<0.01) than the other two groups. Receiver operating curve analysis to predict FW implantation revealed that a PDI of 0.42 in lead V1 (Area under the curve [AUC]=1.00, specificity=100.0%, sensitivity=100.0%, P<0.01) and a QRS duration of 173 msec (AUC=0.89, specificity=100%, sensitivity=66.7%, P<0.01) were the optimal cutoff values. Conclusion The LLP FW implantation group had a longer QRS duration, a notched QRS complex in lead III, and a shorter PDI in lead V1 compared to the other pacing sites.