Review of conduction system pacing

Presented at Medicine Grand Rounds, Medical University of South Carolina, August 2024

1. Conduction System Pacing Sergio L Pinski MD, FHRS Medical University of South Carolina Ralph H. Johnson VA Medical Center Charleston, South Carolina, USA @ SergioPinski

2. Cardiac pacemaker : one of the top inventions of the 20 th century National Society of Professional Engineers 10 top engineering feats 1934-1994 Nylon First working nuclear pile ENIAC electronic computer The transistor Boeing 707 jet airline Inertial navigation guidance system Telstar communications satellite Apollo 11 Helium-neon laser Implantable pacemaker

3. Redwood. Br Med J 1969;1:29 Dismal natural history of patients with Stoke-Adams attacks

4. Miyazawa et al. Card Electrophysiol Clin 2022;14:133 Immediate improvement of hemodynamics with RV pacing in complete heart block

5. Dual-chamber pacemakers Dual-chamber ( ie , right atrial and right ventricular leads) became standard in the late 80s Dual-chamber implantable defibrillators followed in the mid 90s Units also incorporated rate-responsiveness, the capability to detect the patient activity (generally a motion sensor) and increase the pacing rate accordingly to mimic the sinus node This was heralded as “physiologic pacing”

6. Sgarbossa et al. Ann Intern Med 1993;119:359

7. Dual- chamber pacing was not significantly better tan single- chamber pacjng in randomized studies Toff et al. NEJM 2005;353:145 Lamas et al. NEJM 2002;346:1854 Sinus node dysfunction AV block

8. Every incremental 1% of VP increases the risk for heart failure hospitalizations by 5% Sweeney et al. Circulation . 2003:107:2932.

9. Study stopped early due to evidence of harm with active AV pacing Better quality of life without active pacing Harm depended on DDDR patients who had >40% ventricular pacing Detrimental effect of right ventricular stimulation established in the randomized DAVID study 506 patients with ICD indication (LVEF <40%) but no pacing indication randomized to dual-chamber active pacing DDDR 70 BPM vs back up ventricular pacing VVI 40 BPM Wilkoff et al. JAMA 2002; 288:3115

10. Detrimental acute and chronic effects of right ventricular pacing Contraction follows excitation. Electrical dyssynchrony leads to mechanical dyssynchrony Less coordinated contraction Drop in LV ejection fraction Drop in cardiac output and increase in filling pressure Increase in myocardial oxygen consumption Adverse remodeling, chamber enlargement Fibrosis

11. Detrimental effect of short term RV pacing on LVEF Nahlawi et al. JACC 2004;44:1883

12. Incidence of RV pacing-induced cardiomyopathy in patients with AV block and preserved LV systolic function Kiehl et al. Heart Rhythm 2016;13:2272

13. Pacing-induced cardiomyopathy is generally reversible when electrical synchrony is restored Khurshid & Frankel. Cardiol Clin 2023;41:449

14. Prevention of pacing-induced cardiomyopathy Minimize ventricular stimulation when not needed. Feasible only in patients paced for sinus node dysfunction Single-chamber atrial pacing: risk of AV block in follow up Atrial pacing modes with ventricular back up pacing Have to tolerate long, at times non physiologic, PR intervals Pauses triggered by paroxysmal heart block, can be symptomatic and even arrhythmogenic

15. Ideal universal method would entail minimizing electrical dyssynchrony

16. Dilated Cardiomyopathy Normal Longer Relaxed Shorter Curry CW, et al. Circulation 2000;101:e2. LV dyssynchrony in dilated cardiomyopathy with left bundle branch block

17. Biventricular pacing: original cardiac resynchronization therapy LV epicardial pacing obtained by a transvenous lead inserted in a lateral coronary vein via the coronary sinus In the US, most often delivered with defibrillator back-up Despite improvement in techniques, feasible in less than 90% of candidates due to anatomical limitations

18. DCM - Intrinsic DCM - Resynchronization Resynchronization Therapy

19. Figure 2 Sipahi et al. Amer Heart J 2012; 163:260 I:10.1016/j.ahj.2011.11.014 ) Cardiac resynchronization therapy is one of the most studied and established treatments in cardiology

20. Ploux et al. Heart Rhythm 2015:12:782 Biventricular pacing achieves imperfect resynchronization

21. Conduction system of the heart

22. Conduction system pacing would act as an electrical “bypass” Sdogkos et al. Heart Failure Rev 2024;29:45

23. Potential advantages of conduction system pacing Maintain LV function, prevent development of pacing-induced cardiomyopathy in patients with bradycardic indication for pacing. Equal or supersede biventricular pacing as method of resynchronization in patient with ventricular dyssynchrony (mainly left bundle branch block) and heart failure.

24. 3830 Lead Specifications: 4.1 FR lead body diameter Bipolar Fixed screw helix Steroid eluting Polyurethane outer insulation Cable inner conductor

25. Zanon et al. Europace 2018;20:1819

26. Selective His bundle capture @ SergioPinski

27. @ SergioPinski Non-selective to selective His capture during threshold testing

28. Non- selective His Bundle Pacing does not Produce LV Dysynchrony Vijayaraman et al. JACC 2018; 72:927

29. Abdelrhaman et al. JACC 2018; 71:2319 Clinical Outcomes of His Bundle Pacing Compared to Right Ventricular Pacing

30. @ SergioPinski Permanent His bundle pacing can correct LBBB and restore LV synchrony

31. Upadhyay et al. Circulation 2019;139:1876

32. His bundle pacing as a bailout is accepted indication

33. Keene et al. J Cardiovasc Electrophysiol 2019; 30:1984 Huang et al. Heart 2019;105;137 Pacing threshold to correct LBBB can be high

34. Muthumala et al. J Thorac Dis 2019;11:1742 Direct left bundle branch pacing Huang et al. Heart Rhythm 2020; 16:1791

35. Jastrzębski et al. Europace 2020; 22:156

36. Selective and non selective LBB capture Huang et al. Heart Rhythm 2019;16:1791

37. Site of capture and morphology of the QRS Jastrzębki et al. Eur Heart J 2022;43:4161

38. Criteria for LBB capture Huang et al. Heart Rhythm 2019 ; 16:1791 Unipolar paced QRS with RBBB morphology LBB potential Pacing stimulus to peak R wave in V5-V6 ( ie , LVAT, “short”, does not change with increasing output) Non- selective to selective , or non- selective to septal with reduction in output, rapid pacing , or extrastimulus

39. Fixed cutoff criteria for LBB capture Jastrzębski et al. Heart Rhythm 2021;18:943 Optimal 82.5 ms 100% specificity 74 ms Optimal 101 ms 100% specificity 80 ms

40. Complications of left bundle branch pacing LBB area pacing lead complications 8.3% Acute perforation to LV 3.7% Lead dislodgement 1.5% Acute chest pain 1 % Capture threshold rise 0.7% Acute coronary syndrome 0.4% Trapped/damaged helix 0.4% Delayed perforation to LV 0.1% Other 0.7% Jastrzębki et al. Eur Heart J 2022;43:4161

41. Performance of His vs left bundle branch pacing leads Vijayarman et al. Heart Rhythm 2024; (in press)

42. Combining LBBAP and LV pacing Jastrzębski et al. Heart Rhythm 2022;19:13

43. Multicenter observational comparison of LBB vs biventricular pacing in candidates for resynchronization Vijayarman et al. JACC 2023;82:228

44. Conduction system pacing may prevent ventricular tachyarrhythmias Herweg et al. Circulation 2024;149:379

45. 2023 conduction pacing guidelines: pts with pacing indication

46. Clinical Outcomes After the Ablation of the AV Junction in Patients with Atrial Fibrillation : Impact of CRT Mittal et al. J Am Heart Assoc 2017:6:e007270

47. @ SergioPinski

48. Huang et al. Heart Rhythm 2022;19:1948 Randomized, cross-over comparison of His bundle pacing vs biventricular pacing c ombined w ith a trioventricular n ode a blation in permanent atrial f ibrillation with h eart f ailure w ith r educed LVEF RV His LV

49. AV nodal ablation and left bundle branch pacing Chaumont et al. Arch Cardiovasc Dis 2024; (in press)

50. Meta-analysis of improvement in LVEF with LBB pacing El Iskandarani et al. J Cardiovasc Electrophysiol 2024;35:1536

51. Conduction system pacing improves LV function more than biventricular pacing in randomized studies Felix et al. Heart Rhythm 2024:21:881

52. 2023 conduction pacing guidelines: pts with atrial fibrillation

53. 2023 conduction pacing guidelines: pts with heart failure and no bradycardia pacing indication

54. Left bundle pacing with new defibrillation lead Ponnusamy et al. Heart Rhythm 2024; (in press)

55. Ongoing Randomized Clinical Trial: Conduction System Pacing vs Biventricular Pacing

56. Leadless pacemaker: now also available in a dual-chamber configuration Ip J. Heart Rhythm 2024;21:488

57. Two visions of the future of cardiac pacing Physiologic pacing (His, LBB) Leadless Grassroots movement – Little support from companies Promoted by companies Technology relatively primitive Technology rapidly improving Potential for more complications Potential for fewer complications ( ie , infection) Less expensive More expensive Bradycardia and resynchronization Bradycardia alone

58. Conclusions Conduction system pacing represents a true paradigm shift Provides functional resynchronization with a single lead Technological improvements needed and forthcoming Criteria for left bundle branch capture need refinement Conduction system pacing has the potential to completely prevent pacing-induced cardiomyopathy. Currently useful bailout for challenging biventricular device Randomized clinical trials will determine if conduction system pacing can replace biventricular pacing in most resynchronization indications