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Kusumoto et al 2018 Bradycardia Clinical Practice Guidelines

Circulation. 2019;140:e382–e482. DOI: 10.1161/CIR.0000000000000628 August 20, 2019 e443 CLINICAL STATEMENTS AND GUIDELINES

for approximately 80% of cases.S8.1.2.5.1-1–S8.1.2.5.1-4 A pathology study has identified individual patients in whom the conduction system was affected preferentially during allograft rejection, but a relationship between bradycardia and allograft rejection has not been found more generally in analyses of large databases.S8.1.2.5.1-1–S8.1.2.5.1-5 Guidelines for the use of permanent pacing are the same for those that apply generally for SND and atrioventricular block, and in particular careful evaluation for the presence of symptomatic SND (Online Data Supplement 50).

8.1.2.5.2 Surgical Myectomy and Alcohol Septal Ablation for Hypertrophic Cardiomyopathy

Recommendations for Patients Undergoing Surgical Myectomy or Alcohol Septal Ablation for Hypertrophic Cardiomyopathy Referenced studies that support recommendations are summarized in Online Data Supplements 51 and 52.

COR LOE Recommendations

I B-NR 1.  In patients with second-degree Mobitz type II atrioventricular block, high-grade atrioventricular block, or persistent complete atrioventricular block after alcohol septal ablation or surgical myectomy, permanent pacing is recommended before discharge.S8.1.2.5.2-1–S8.1.2.5.2-4

IIa B-NR 2.  In selected patients with hypertrophic cardiomyopathy who require permanent pacing for rate support after alcohol septal ablation or surgical myectomy and are at high risk for sudden cardiac death and meaningful survival of greater than 1 year is expected, selecting a device with defibrillator capabilities is reasonable.S8.1.2.5.2-5–S8.1.2.5.2-7

IIb C-LD 3.  In patients with hypertrophic cardiomyopathy who undergo alcohol septal ablation and who are at risk for developing late atrioventricular block, prolonged ambulatory electrocardiographic monitoring may be considered.S8.1.2.5.2-1,S8.1.2.5.2-2,S8.1.2.5.2-

4,S8.1.2.5.2-7,S8.1.2.5.2-8

IIb C-LD 4.  In patients with hypertrophic cardiomyopathy, evaluation of ventriculoatrial conduction by EPS at the time of alcohol septal ablation may be considered for identifying future risk of atrioventricular block.S8.1.2.5.2-9

Synopsis

In patients with hypertrophic cardiomyopathy and symptoms attributable to left ventricular outflow tract obstruction, surgical myectomy or alcohol septal ablation may be used to reduce septal thickness and improve symptoms.S8.1.2.5.2-10 Risk of abnormal atrioventricular conduction varies widely among observational studies with estimates of 10% to 33% for alcohol septal ablation and 3% to 4% for surgical myectomy.S8.1.2.5.2-10–S8.1.2.5.2-15 The wide reported range is in part attributable to differences in baseline conduction properties. For example, in patients undergoing surgical myectomy requirement for permanent pacing was 2% but increased to 10% if baseline conduction abnormalities were present.S8.1.2.5.2-13 A meta-analysis of observational studies suggests that the risk of abnormal atrioventricular conduction requiring permanent pacing is higher with alcohol septal ablation relative to myectomy (10% versus 4.4%).S8.1.2.5.2-11 However, a recent analysis of the National Inpatient Sample Database found similar 9% to 14% requirements for PPM for both alcohol septal ablation and surgical myectomy.S8.1.2.5.2-16 Development of RBBB is observed in approximately 60% of patients after alcohol septal ablation and up to 90% of patients develop LBBB after surgical myectomy.S8.1.2.5.2-13,S8.1.2.5.2-15

Recommendation-Specific Supportive Text

1.	 Transient atrioventricular block after alcohol septal ablation is observed in approximately 15% to 50% of patients and usually resolves within 24 hours.S8.1.2.5.2-1–S8.1.2.5.2-4,S8.1.2.5.2-11–S8.1.2.5.2-15 The development of intraprocedural atrioventricular block is more likely in patients with preexisting LBBB, older patients, women, and the use of larger doses of ethanol.S8.1.2.5.2-17 Protocols for implantation of a PPM varied from study to study, but most implanted a PPM if complete atrioventricular block was present >24 hours after alcohol septal ablation although actual time of implant varied with a range of 2 to 7 days. In some studies, patients with persistent complete atrioventricular block >24 hours commonly required permanent pacing for rate support at 2 weeks while, in other studies, recovery of atrioventricular conduction was observed in most patients.S8.1.2.5.2-2–S8.1.2.5.2-4,S8.1.2.5.2-13 PPMs are implanted in 2% to 10% of patients after septal myectomy usually for persistent complete heart block.S8.1.2.5.2-15,S8.1.2.5.2-18 2.	 Selected patients with hypertrophic cardiomyopathy are at risk for sudden cardiac death. The 2011 ACCF/AHA guidelines for the diagnosis and treatment of hypertrophic cardiomyopathy and the 2017 AHA/ACC/HRS ventricular arrhythmias and sudden cardiac death guidelines have identified several risk factors for sudden cardiac death including prior history of ventricular arrhythmias, a family history of sudden cardiac death, unexplained syncope, and a maximal left ventricular wall thickness ≥30 mm.S8.1.2.5.2-5–S8.1.2.5.2-7,S8.1.2.5.2-10,S8.1.2.5.2-19 Surgical myectomy has been associated with decreased risk of sudden death in 1 large cohort.S8.1.2.5.2-20 3.	 Late heart block with initial identification >48 hours has been observed in some but not all studies after alcohol septal ablation. Potential risk factors for persistent atrioventricular block

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