This study will evaluate the association between right ventricular pacing and the risk of pacing-induced cardiomyopathy.

Background:

Right ventricular (RV) pacing may lead to pacing-induced cardiomyopathy (PICM) and heart failure (HF). The detrimental effects of RV pacing have been attributed to the abnormal and dyssynchronous electrical and mechanical activation of the myocardium. The activation is affected by the RV pacing site. Understanding the consequences of different RV pacing sites and the patterns of dyssynchrony may help to choose the optimal treatment for the individual patient.

Aim and objectives:

The overall aim of this project is to investigate the association between RV pacing site and the risk of PICM. Contrast enhanced cardiac computed tomography (CT) will be applied for precise localization of the RV pacing. Furthermore, investigation of the association between PICM and different mechanical and electrical myocardial activation patterns during RV pacing will be conducted using new echocardiographic and electrocardiographic methods.

Methods:

The study is designed as a retrospective cohort study with clinical follow-up. Patients with prior pacemaker implantation due to advanced atrioventricular block will be included. The study baseline is retrospective and defined as time of pacemaker implantation and follow-up is time of inclusion. Baseline data will be extracted from the Danish Pacemaker- and ICD Registry, electronic medical records (EMR) and review of echocardiographs. Follow-up data will be extracted from existing data in the EMRs as well as generated during a follow-up visit with a clinical examination. For assessment of cardiac function, RV lead position and electrical and mechanical activations patterns, the examination will include a transthoracic echocardiography, an electrocardiogram, a 3-dimensional chest photo, and a contrast-enhanced cardiac CT. Data will be analysed for differences between those who develop PICM and those who do not.

Expected outcomes and perspectives:

The hope is that this project will generate knowledge and awareness on pacemaker treatment and the risk of PICM. Understanding the pathophysiology behind PICM is key to learning how to prevent it. Accordingly, this project has the potential to contribute to improving pacemaker treatment and the quality of care for the large and still growing PM population.

Inclusion Criteria:

• Male or female ≥ 18 years
• De novo DDD PM implanted at Aalborg University Hospital
• PM implantation due to advanced AV block
• Duration of pacemaker treatment ≥ 1 year at time of screening
• Normal LVEF (≥50%) prior to PM implantation
• Actively attending follow-up at the PM outpatient clinic at Aalborg University Hospital after PM implantation

Exclusion Criteria:

• No written informed consent
• Baseline TTE not available or insufficient quality for assessment of LVEF
• Contraindications to a new contrast CT if no previous contrast-enhanced cardiac CT, showing RV lead position, is available
• RV pacing load < 40%.
• Deceased
• Not attending follow-up at the PM outpatient clinic at Aalborg University Hospital after PM implantation
• Device complications with removal of original implanted pacing lead > 3 months after primary implantation
• Subjects with severe ischemic heart disease and severe valvular heart disease.
• Terminal illness or unable to provide informed consent at time of screening

Subjects with a normal or near-normal ejection fraction prior to pacemaker implantation who received a DDD-pacemaker due to high-degree AV block ≥ 1 years prior to screening.