Abstract
Funding Acknowledgements
Type of funding sources: None.
Introduction
Pacing-Induced Cardiomyopathy (PICM) can lead to significant morbidity, requiring treatment by device upgrade procedures. The risk of occurrence is directly related to the burden of right ventricular pacing, which can be reduced by careful device programming. When frequent ventricular stimulation cannot be avoided, pacing the conduction system may offer an alternative to myocardial pacing and reduce the risk of PICM. The most recent international pacing guidelines recommend that His-bundle pacing should be considered among 1) patients with EF 36-50% and expected to require >40% ventricular pacing (Vp > 40%) (class IIa); and 2) patients requiring pacing who have block at the level of the AV node (class IIb).
Purpose
This study sought to determine how many patients undergoing bradycardia pacing would have fulfilled those criteria.
Methods
This was a single-centre retrospective study over a 5 year period to the end of April 2020. Demographic and clinical details of patients receiving device implants were obtained from the Pacing Service Database, along with the indication for pacing, electrocardiographic and echocardiographic data. A cardiology consultant with a special interest in pacing reviewed each case with regards to the likelihood of requiring >40% ventricular pacing. Heart block at the level of the AV node was considered present if patients presented with a narrow QRS in conjunction with second or third degree heart block.
Results
1,265 patients underwent pacemaker implant for bradycardia during the study period, 888 for conduction system disease (198 second degree block, 333 complete heart block), 349 for sinus node disease and 28 for other indication. Figure 1 gives a breakdown of patients with conduction system block according to i) level of block; ii) ejection fraction; iii) expectation or not of Vp > 40%. In total, 166 patients had a class IIa indication for His-bundle pacing. 227 patients had block at the level of the AV node, of whom 36 also fulfilled the class IIa criteria for His-bundle pacing; 191 patients (16% of the total) had a sole class IIb indication for His-bundle pacing. Adjusting for the 176 patients who did not undergo echocardiography, up to an additional 45 patients may be expected to have an indication for His-bundle pacing
Conclusion
As many as 32% of patients in a bradycardia pacing population may be eligible for His-bundle pacing. This has significant implications for training and service provision. Abstract Figure 1. Flowsheet showing distribution
Permanent His-Bundle pacing in a patient with advanced conduction system disease: What is the mechanism of QRS narrowing?