Key result
His-pacing did not significantly improve global longitudinal strain (-11.1 ms vs -10.8 ms) or mechanical dyssynchrony compared to biventricular pacing at 6 months (P=ns for difference).
Why the study?
The clinical role of His-CRT remains to be established, and whether His-pacing is more efficient than BiV-CRT in improving mechanical synchrony and longitudinal contractile function was unknown.
Does His-pacing improve mechanical synchrony and longitudinal contractile function compared to biventricular pacing in patients with symptomatic heart failure, LVEF ≤35%, and left bundle branch block?
RCT (n=50)
1:1
Does His-pacing improve mechanical synchrony and longitudinal contractile function compared to biventricular pacing in patients with symptomatic heart failure, LVEF ≤35%, and left bundle branch block?
p-value: p=ns
His-bundle pacing and biventricular pacing provide similar improvements in mechanical synchrony and longitudinal contractile function at 6 months in patients with heart failure and left bundle branch block.
Background The clinical role for HIS-pacing in cardiac resynchronization therapy (HIS-CRT) is promising but is yet to be established. The randomised His-alternative study showed better remodelling with HIS-CRT compared to patients receiving conventional biventricular pacing (BIV-CRT) in the per-protocol-analysis. Purpose In this substudy we investigated whether HIS-pacing was more efficient compared to BIV-CRT in improving mechanical synchrony and longitudinal contractile function. Methods In the His-Alternative study 50 patients with symptomatic heart failure, left ventricular ejection fraction (LVEF) ≤35% and Left bundle branch block were randomized 1:1 to His-CRT or BiV-CRT and followed for 6 months. At implantation, 7 patients crossed over from His-pacing to LV-pacing in the His-CRT group and 1 patient crossed over from LV-pacing to His-pacing in the BiV-CRT group. All patients had echocardiography performed including 2D-strain echocardiography to asses global systolic longitudinal deformation (GLS) at baseline and 6 months. Mechanical dyssynchrony was measured as SD of time-to-peak in all 12 segments of the left ventricle (TPS-SD). Results There were no significant differences in baseline characteristics between patients receiving HIS-CRT and BIV-CRT with regard to dyssynchrony and longitudinal systolic strain. LVEF was significantly higher at 6 months (48±8% vs. 42±8%; p<0.05) in the HIS-CRT group. However, GLS did not significantly improve more with HIS-CRT compared to BIV-CRT, (−8.7ms ± 2.0 to −11.1 ms ± 2.0 vs −9.1 ms ± 2.7 to −10.8±2.5 ms ± 2.8, P = ns for difference) and regarding resynchronization measured as TPS-SD there was no significant difference either (110 ms ± 51 to 47 ms ± 10 vs. 115 ms ± 42 to 60 ms ± 21, P = ns for difference). Conclusion In this substudy, HIS-pacing did not prove more efficient than BIV-CRT in resynchronizing the left ventricle, nor did the observed improvement in longitudinal function differ significantly between methods. However, the number of included patients was rather small and larger studies are needed to fully assess the possible benefits of HIS-CRT. Funding Acknowledgement Type of funding sources: None.
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Hoejgaard et al. (2022) conducted an RCT in Symptomatic heart failure with LVEF ≤35% and left bundle branch block (n=50). His-pacing (HIS-CRT) vs. Conventional biventricular pacing (BIV-CRT) was evaluated on Global systolic longitudinal deformation (GLS) and mechanical dyssynchrony (TPS-SD) (p=ns). His-pacing did not significantly improve global longitudinal strain (-11.1 ms vs -10.8 ms) or mechanical dyssynchrony compared to biventricular pacing at 6 months (P=ns for difference).
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