Are all left bundle branch blocks the same? Myocardial mechanical implications by cardiovascular magnetic resonance.

AIMS: Left bundle branch block (LBBB) is usually associated with structural myocardial diseases progressively leading to left ventricular (LV) dysfunction. We sought to determine the mechanical implications of LBBB (as defined based on Strauss' criteria) by Cardiovascular Magnetic Resonance (CMR). METHOD AND RESULTS: We included consecutive patients referred to CMR to assess the structural cause of LBBB. CMR scans consisted of cine, stress perfusion, and late gadolinium enhancement (LGE) sequences. Myocardial deformation was assessed by tissue tracking analysis; LGE was quantified using the full width at half maximum method. We included 86 patients [63% male, 70 years (60-72)] with mean QRS duration 150 ± 13 msec. A structural disease was identified on CMR in 53% of patients (ischemic heart disease, IHD, 31%; non-ischemic heart disease, NIHD, 22%), while LBBB-related septal dyssynchrony (SD) was the only abnormality in 47%. LGE was found in 42% of patients. LVEF and myocardial deformation were impaired. Despite similar ECG characteristics, myocardial strain differed significantly between IHD, NIHD and SD patients, and patients with SD showed less impaired myocardial deformation. Indexed LV end-systolic volume and LGE extent were independently associated with impaired strain. CONCLUSIONS: Patients with LBBB show different structural and mechanical properties, and LGE extent has an unfavourable effect on myocardial mechanics.

A pilot image interpretation teaching intervention to improve competence and confidence of radiographers to detect left ventricular thrombus in routine cardiac MRI scans.

INTRODUCTION: Prompt diagnosis of left ventricular (LV) thrombus is clinically important, as it may require immediate anti-coagulation treatment. The aim of this study was to determine if a teaching intervention delivered by cardiovascular magnetic resonance (CMR) physicians would increase the CMR radiographers' ability to detect LV thrombus on a routine CMR scan. METHODS: A cohort of 25 patients (14 with and 11 without LV thrombus) were identified. A multi-parametric CMR protocol had been performed in all patients. Ten radiographers reviewed the 25 randomised anonymised studies on a workstation, documenting the presence/absence of LV thrombus and their confidence level on a 7-point Likert scale. Two senior CMR fellows then delivered a focused teaching programme to the radiographers and all 25 randomised scans were reassessed 1 month after the teaching intervention. RESULTS: Following dedicated training, there was a significant improvement in correct thrombus identification per radiographer (pre-training: 75 ± 6% vs post-training: 85 ± 6%, p = 0.009). The size of the thrombus was not associated with the likelihood of incorrectly identifying LV thrombus size prior to the training session (p = 0.2), but a trend was observed between smaller thrombus size and incorrect identifications post-training (p = 0.06). The radiographers' overall confidence in assessing the cases prior to the teaching session was high (5.6 ± 0.8 out of 7). Following the teaching session, self-reported confidence did not vary significantly (5.9 ± 0.7 out of 7, p = 0.42). When evaluating the teaching session, radiographers provided very positive feedback, rating the usefulness of the teaching intervention as highly educative (8.8 ± 0.4 out of 10). CONCLUSIONS: This is the first study that has explored the ability and confidence of CMR radiographers in detecting LV thrombus on routine CMR scans as a result of the teaching intervention delivered by CMR physicians. IMPLICATIONS FOR PRACTICE: A teaching intervention can improve CMR radiographers' diagnostic skills and diagnostic confidence.