Electrocardiographic predictors of successful resynchronization of left bundle branch block by His bundle pacing
Ahran D Arnold1, Matthew J Shun-Shin1, Daniel Keene
1National Heart and Lung Institute, Imperial College London, Hammersmith Hospital, London, UK.
Insights
His bundle pacing (HBP) can effectively resynchronize the ventricles in most patients with left bundle branch block (LBBB), potentially restoring normal heart activation patterns. This method may offer superior resynchronization compared to biventricular pacing (BVP).
Area of Science:
- Cardiology
- Electrophysiology
- Medical Devices
Background:
- His bundle pacing (HBP) is an alternative to biventricular pacing (BVP) for cardiac resynchronization therapy (CRT) in heart failure patients with left bundle branch block (LBBB).
- The equivalence of HBP-achieved ventricular activation to intact conduction systems and its resynchronization efficacy in all LBBB patients remain unclear.
Purpose of the Study:
- To compare ventricular activation times and patterns between His bundle pacing CRT (His-CRT), biventricular pacing CRT (BVP-CRT), LBBB, and intact conduction systems.
Main Methods:
- Noninvasive epicardial mapping (ECG imaging) was used in LBBB patients during BVP and temporary HBP.
- Intrinsic activation was mapped, and left ventricular activation times (LVAT) were measured.
- Epicardial propagation mapping (EPM) visualized wavefronts, with normal patterns established from healthy subjects.
Main Results:
- His-CRT shortened LVAT by ≥10 ms in 87.5% of LBBB patients.
- Complete ventricular resynchronization, indistinguishable from normal subjects, was achieved in 33.3% of LBBB patients with His-CRT.
- EPM identified propagation discontinuity in 83% of LBBB patients, predicting successful HBP resynchronization (p=0.04).
Conclusions:
- Noninvasive electrocardiographic mapping can identify LBBB patients suitable for HBP resynchronization.
- His-CRT may achieve maximal ventricular resynchronization, restoring normal activation times and patterns, potentially surpassing BVP.
- HBP offers a promising approach to optimize CRT in specific LBBB patient populations.
Background:
His bundle pacing (HBP) is an alternative to biventricular pacing (BVP) for delivering cardiac resynchronization therapy (CRT) in patients with heart failure and left bundle branch block (LBBB). It is not known whether ventricular activation times and patterns achieved by HBP are equivalent to intact conduction systems and not all patients with LBBB are resynchronized by HBP.
Objective:
To compare activation times and patterns of His-CRT with BVP-CRT, LBBB and intact conduction systems.
Methods:
In patients with LBBB, noninvasive epicardial mapping (ECG imaging) was performed during BVP and temporary HBP. Intrinsic activation was mapped in all subjects. Left ventricular activation times (LVAT) were measured and epicardial propagation mapping (EPM) was performed, to visualize epicardial wavefronts. Normal activation pattern and a normal LVAT range were determined from normal subjects.
Results:
Forty-five patients were included, 24 with LBBB and LV impairment, and 21 with normal 12-lead ECG and LV function. In 87.5% of patients with LBBB, His-CRT successfully shortened LVAT by ≥10 ms. In 33.3%, His-CRT resulted in complete ventricular resynchronization, with activation times and patterns indistinguishable from normal subjects. EPM identified propagation discontinuity artifacts in 83% of patients with LBBB. This was the best predictor of whether successful resynchronization was achieved by HBP (logarithmic odds ratio, 2.19; 95% confidence interval, 0.07-4.31; p = .04).
Conclusion:
Noninvasive electrocardiographic mapping appears to identify patients whose LBBB can be resynchronized by HBP. In contrast to BVP, His-CRT may deliver the maximum potential ventricular resynchronization, returning activation times, and patterns to those seen in normal hearts.
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