Influence of left bundle branch block on left atrial strain parameters in patients with ischaemic and non-ischaemic dilated cardiomyopathy

Left atrial (LA) strain parameters predict mortality in patients with ischaemic/non-ischaemic dilated cardiomyopathy (DCM). Left bundle branch block (LBBB) is a common conduction abnormality in those patients. To date, the impact of LBBB on LA strain parameters assessed by cardiovascular magnetic resonance imaging (cMRI) has not been studied systematically. In this retrospective single-centre study, we included 20 (10 female) controls without DCM or LBBB, 21 (11 female) patients with LBBB without DCM, 20 (7 female) patients with DCM without LBBB, and 20 (9 female) patients with DCM and LBBB. LA volumes and strain were assessed semi-automatically using the cvi42® and Segment® software. LA reservoir/conduit strain and corresponding strain rates were significantly impaired in patients with DCM (p = 0.003/0.022 respectively < 0.001/0.004) in comparison to controls. The presence of LBBB did not lead to significant changes of LA reservoir/conduit strain in controls (p = 0.919/0.391) nor in patients with DCM (p = 0.862/0.999), same was true for LA reservoir/conduit strain rate in patients with DCM (p = 0.999/0.812). LA conduit strain rate of patients with LBBB was significantly impaired in comparison to controls (p = 0.005). Left ventricular dilatation was associated with significantly impaired LA reservoir/conduit strain/strain rates. The presence of LBBB was not associated with additional impairment in LA strain/strain rate parameters in patients with ischaemic/non-ischaemic DCM, supporting the robustness of LA functional parameters in the presence of this common conduction abnormality. However, in patients with LBBB without dilatation LA conduit strain rate was significantly impaired in comparison to controls and further studies are needed to evaluate the impact of this finding.