Abstract
BackgroundLeft bundle branch block (LBBB) is common following trans-catheter aortic valve replacement (TAVR) and has been linked to increased mortality, although whether this is related to less favourable cardiac reverse remodeling is unclear. The aim of the study was to investigate the impact of TAVR induced LBBB on cardiac reverse remodeling.Methods48 patients undergoing TAVR for severe aortic stenosis were evaluated. 24 patients with new LBBB (LBBB-T) following TAVR were matched with 24 patients with a narrow post-procedure QRS (nQRS). Patients underwent cardiovascular magnetic resonance (CMR) prior to and 6 m post-TAVR. Measured cardiac reverse remodeling parameters included left ventricular (LV) size, ejection fraction (LVEF) and global longitudinal strain (GLS). Inter- and intra-ventricular dyssynchrony were determined using time to peak radial strain derived from CMR Feature Tracking.ResultsIn the LBBB-T group there was an increase in QRS duration from 96 ± 14 to 151 ± 12 ms (P < 0.001) leading to inter- and intra-ventricular dyssynchrony (inter: LBBB-T 130 ± 73 vs nQRS 23 ± 86 ms, p < 0.001; intra: LBBB-T 118 ± 103 vs. nQRS 13 ± 106 ms, p = 0.001). Change in indexed LV end-systolic volume (LVESVi), LVEF and GLS was significantly different between the two groups (LVESVi: nQRS -7.9 ± 14.0 vs. LBBB-T -0.6 ± 10.2 ml/m2, p = 0.02, LVEF: nQRS +4.6 ± 7.8 vs LBBB-T -2.1 ± 6.9%, p = 0.002; GLS: nQRS -2.1 ± 3.6 vs. LBBB-T +0.2 ± 3.2%, p = 0.024). There was a significant correlation between change in QRS and change in LVEF (r = -0.434, p = 0.002) and between change in QRS and change in GLS (r = 0.462, p = 0.001). Post-procedure QRS duration was an independent predictor of change in LVEF and GLS at 6 months.ConclusionTAVR-induced LBBB is associated with less favourable cardiac reverse remodeling at medium term follow up. In view of this, every effort should be made to prevent TAVR-induced LBBB, especially as TAVR is now being extended to a younger, lower risk population.
Highlights
Left bundle branch block (LBBB) is common following trans-catheter aortic valve replacement (TAVR) and has been linked to increased mortality, whether this is related to less favourable cardiac reverse remodeling is unclear
Matching 24 patients with TAVR-induced left bundle branch block (LBBB-T) were identified. These were matched with 24 patients with a narrow post-procedure QRS (nQRS) post-procedure for sex, valve type, and baseline cardiovascular magnetic resonance (CMR) variables known to impact on reverse remodeling following TAVR including left ventricular (LV) ejection fraction (LVEF), indexed LV mass and indexed LV end diastolic volume (LVEDVi) [16] (Fig. 1)
3 patients died within the 6 m follow up period and 5 patients declined follow up (Fig. 1). 24 patients with LBBB-T and 41 patients with nQRS on discharge electrocardiogram completed both baseline and 6 m scans and were available for retrospective matching in a 1:1 fashion (Fig. 1). 48 patients were included in the final analysis, 24 with LBBB-T and 24 with nQRS
Summary
Left bundle branch block (LBBB) is common following trans-catheter aortic valve replacement (TAVR) and has been linked to increased mortality, whether this is related to less favourable cardiac reverse remodeling is unclear. TAVR-induced left-bundle branch block (LBBB-T) has been linked to reduced survival [3,4,5] and increased hospitalisation [6], in keeping with population based studies suggesting reduced overall survival in healthy individuals with LBBB [7] and in patients with heart failure and LBBB [8]. The mechanism for this increased mortality is debated; one hypothesis is that LBBB-T is a precursor to further more lethal conduction abnormalities [9], another is that LBBB-T leads to abnormal left ventricular (LV) remodeling and heart failure death via a LBBB-induced cardiomyopathy [10]. The novel technique of feature tracking allows accurate estimation of global longitudinal strain (GLS) and inter- and intraventricular dyssynchrony which are of interest in this population and may be able to assess the impact of LBBB on cardiac function beyond simple mechanical dyssynchrony [14]
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