What to consider in a patient with a new left bundle branch block (LBBB) after transcatheter aortic valve replacement (TAVR), besides using an event monitor?

Management of New LBBB After TAVR

In patients with new LBBB after TAVR, you must extend inpatient telemetry monitoring for at least 2 days (up to 7 days if no ambulatory monitoring planned), followed by ambulatory electrocardiographic monitoring for at least 14 days post-discharge, with infrastructure to respond to high-degree AV block within one hour. 1

Inpatient Monitoring Strategy

Prolonged telemetry is essential because high-degree AV block (DH-AVB) can develop days after the procedure, with most events clustering within the first 7-8 days post-TAVR. 1

• Minimum 2 days of inpatient telemetry if the conduction disturbance remains stable and you plan to use ambulatory monitoring after discharge 1
• Up to 7 days of inpatient telemetry if ambulatory electrocardiographic monitoring (AEM) will NOT be employed post-discharge 1
• This applies to any patient with new or worsened conduction disturbance (PR or QRS interval increase ≥10%) 1

The rationale: In the MARE trial, 10% of patients with new-onset persistent LBBB developed DH-AVB requiring permanent pacemaker (PPM), occurring at a median of 30 days post-TAVR (range 5-281 days). 1 One fatal case involved syncope with intracranial hemorrhage in a patient without routine monitoring. 1

Post-Discharge Ambulatory Monitoring

Ambulatory electrocardiographic monitoring for ≥14 days is appropriate for any patient with new LBBB or PR/QRS interval extended by ≥10%. 1

• The monitoring system must have capacity to receive and respond to DH-AVB within one hour and dispatch emergency medical services 1
• In studies, 10% of patients developed DH-AVB at a median of 6 days post-discharge (range 3-24 days), with most events within 8 days 1
• Importantly, 29% of patients with new LBBB experience their first episode of high-degree AV block AFTER discharge 1

Critical caveat: DH-AVB has been documented even in patients with normal pre- and post-TAVR ECGs, and 14-30 days of monitoring may not capture all occurrences. 1

Consider Electrophysiology Study

Intraprocedural or early post-procedure EP study with His-ventricular (HV) interval measurement can risk-stratify patients with new LBBB. 2, 3

• HV interval ≥65 ms after TAVR is modestly predictive of high-grade AV block (sensitivity 80%, specificity 79%) 1
• HV interval >70 ms or significant HV prolongation (>30% increase) with procainamide challenge warrants strong consideration for PPM 3
• HV interval <55 ms intraprocedurally can safely exclude infrahisian conduction delay and facilitate discharge with ambulatory monitoring 2, 3

In one study, among patients with new LBBB post-valve deployment, 45% had infranodal conduction delay intraprocedurally, but 66% had LBBB resolution by the next day. 2 Patients with normal HV intervals intraprocedurally did not develop prolongation to >55 ms the following day. 2

Permanent Pacemaker Considerations

PPM implantation may be considered for new persistent LBBB, though evidence is mixed (Class IIb recommendation). 1

• Definite PPM indication: New AV block with symptoms or hemodynamic instability that does not resolve (Class I) 1
• Studies show 11.5-15.2% of patients with new LBBB require PPM within one year 4
• However, early PPM for new LBBB is NOT protective against increased mortality 1
• Among patients who receive PPM for new LBBB, only 3.5-11% are completely pacemaker-dependent at follow-up, and 24% recover left bundle conduction (median 5 weeks) 5

Clinical Outcomes to Monitor

New LBBB after TAVR is associated with worse clinical and echocardiographic outcomes, independent of PPM placement:

• Higher 1-year heart failure hospitalizations (10.7% vs 4.4%) 6
• Lower LVEF at 30 days and 1 year (55.9% vs 59.3% at 30 days; 55% vs 60.1% at 1 year) 6
• Higher LV end-diastolic and end-systolic volume indices at 1 year 6
• Persistent LBBB (vs resolved) is associated with worse LVEF and higher PPM rates 6
• No difference in 3-year mortality compared to patients without new LBBB (30.9% vs 30.6%) 6

Practical Algorithm

1. Identify new LBBB or QRS/PR prolongation ≥10% on post-TAVR ECG
2. Extend inpatient stay: Minimum 2 days telemetry (up to 7 days if no outpatient monitoring available) 1
3. Consider EP study with HV interval measurement before discharge 2, 3
   • HV >70 ms or significant prolongation with procainamide → discuss PPM
   • HV <55 ms → safe for discharge with monitoring
4. Arrange ≥14 days ambulatory monitoring with rapid-response capability 1
5. Serial ECGs and echocardiography to assess for LBBB resolution and LV function 6
6. Close follow-up as PPM requirement can occur up to 1 year post-TAVR 4