34 The consequence of long-term RV pacing dependence: a case study

Introduction Pacemaker implantation is a definitive and recommended treatment for atrioventricular heart block. While demand for pacemaker implantation is rising with our aging demographic- pacemakers may also be indicated in other circumstances. Although complications are rare, there may be significant implications for our patients. We present the case of a young man who had a pacemaker inserted as part of a complex management strategy for cardiac arrhythmia. Case Summary In 2006 our then 40 year old gentleman had a dual chamber pacemaker inserted for complete AV block following radiofrequency ablation for supraventricular arrhythmia. He had a history of problematic atrial fibrillation and had a prior failure of medical therapy and an ablation. He was able to return to a very active life despite being pacing dependant and there were no pacemaker complications. He attended for uncomplicated box changes in 2014 and 2022. In early 2023, aged 57, he presented with NYHA 2–3 symptoms. He had a significant reduction in his functional capacity, he was unable to exercise and his quality of life was poor. A transthoracic echocardiogram demonstrated new regional wall motion abnormalities with apical hypokinesis and wall thinning, an ejection fraction of 46% and a reduction in longitudinal global strain -14% Fig 1. A CT Coronary Angiogram was carried out which concluded there was atherosclerosis but no obstructive coronary artery disease Fig 2. There was no evidence of SCAD, pericardial effusion, pulmonary embolism or lung disease. Cardiac CT imaging also confirmed thinning of myocardium at LV apex. While a MINOCA event was considered the clinical history was not suggestive. A diagnosis of PICM was considered. Our patient was established on guideline directed medical therapy for HFrEF and following optimisation his imaging confirmed that cardiac function had normalised. Discussion Pacemaker induced cardiomyopathy (PICM) is a potential harmful side effect of chronic RV pacing. There is no clear international consensus on a definition for PICM. However it is generally recognised as a fall in LVEF to less than 50% or a decrease in overall LVEF by 10–15% following pacemaker insertion. Chronic RV pacing results in dyssynchronous RV and LV electrical and mechanical activation. Over time this causes asymmetric remodelling and thinning of LV. Retrospective analysis have helped to identify independent early predictors for PICM, including paced QRS duration, RV pacing percentage and LBBB. An RV pacing threshold of >40% is associated with higher cardiovascular mortality. This a particularly important risk factor in patients like our case who are 100% RV pacing dependant. The overall burden of atrial fibrillation is also thought to increase RV pacing dependence. Our patient fulfilled a number of these noted risk factors for PICM. Definitive management of PICM is uncertain. Initiation of HF medications, CRT upgrade and HBP may improve LVEF and clinical symptoms. Conflict of Interest None