Roles of MDA-LDL/OX-LDL/LOX-1 and TNF-α/TLR4/NF-κB Signaling Pathways in Myocardial Damage by Implantations of Cardiac Pacemakers in Elderly Patients

Introduction: Permanent pacemakers are an established treatment for sick sinus syndrome and high-grade atrioventricular block. Permanent cardiac pacemaker implantations may damage the myocardium. Objective: This study evaluated markers of myocardial injury, oxidative stress and inflammation in elderly patients with permanent pacemaker implantations. Methods: Various markers were measured at 1, 2, 3 and 4 months after permanent pacemaker implantations in elderly patients. Results: The levels of high-sensitivity troponin T (hsTnT), lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1), malondialdehyde-modified low-density lipoprotein (MDA-LDL), oxidized low-density lipoprotein (OX-LDL), tumour necrosis factor-alpha (TNF-alpha), toll-like receptor 4 (TLR4) and nuclear factor-kappa B (NF-kappa B) were increased in 2-month group compared with control and 1- month groups (P<0.001), and were further increased at 4-month group compared with 2- and 3- month groups after pacemaker implantations (P<0.001). Patients with dual-chamber pacemakers had higher levels of hsTnT, LOX-1, MDA-LDL, OX-LDL, TNF-alpha, TLR4 and NF-kappa B than patients with single chamber pacemakers (P<0.001). Patients who underwent the pacemakers with the active fixation leads had raised levels of hsTnT, LOX-1, MDA-LDL, OX-LDL, TNF-alpha, TLR4 and NF-kappa B compared patients with pacemakers using the passive fixation leads (P<0.001). Myocardial blood flows in 3-month and 4-month groups were lower than 1-month and 2-month groups (P<0.001). Conclusion: Levels of hsTnT, LOX-1, MDA-LDL, OX-LDL, TNF-alpha, TLR4 and NF-kappa B were elevated in elderly patients with permanent pacemaker implantations and the activations of oxidative stress and pro-inflammatory signalling pathways may be associated with myocardial damages and ischemia after pacemaker implantations in elderly patients.