HIS BUNDLE VS. RV MYOCARDIAL PACING AND BIOMARKERS OF COLLAGEN METABOLISM AND FIBROSIS IN DETECTION OF NEGATIVE LV REMODELLING

Background
His bundle pacing (HBP) represents physiological method of cardiac pacing. RV myocardial pacing (RVMP) can result in negative left ventricular (LV) remodelling which is reflected in left ventricular ejection fraction (LVEF) decline and should also be reflected in changes of plasmatic levels of biomarkers of collagen metabolism and fibrosis.

Purpose
To investigate a change in the LVEF and plasmatic levels of selected biomarkers in HBP and RVMP in patients with significant bradycardia after six months of follow-up.

Methods
Patients with bradycardia were randomised to HBP or RVMP. Echocardiographic examination and plasmatic concentrations of matrix metalloproteinase 9 (MMP), tissue inhibitor of metalloproteinase 1 (TIMP), galectin-3 (GAL), ST2/IL-33R (ST2) and transforming growth factor β1 (TGF) were collected on the 1st and 180th day after randomisation.

Results
Forty-nine patients had RVMP and 43 patients had HBP during the study period. Both groups had similar baseline clinical characteristics, baseline levels of studied cytokines and burden of ventricular pacing. LVEF significantly declined in RVMP group, but remained the same in HBP group– Figure 1. No patients with HBP required an upgrade to cardiac resynchronization therapy, compared to six patients from RVMP group (p = 0,057). After six months of pacing a significant decline of ST2 and TIMP was observed in RVMP group. In the HBP group ST2, MMP, and TGF significantly declined and plasmatic concentrations of TGF were significantly lower compared to RVMP group – Figure 2.

Conclusion
HBP in contrary to RVMP preserves LVEF. The plasmatic levels of TGF could potentially serve as a marker of RVMP detrimental effect.