Feature tracking strain analysis detects the onset of regional diastolic dysfunction in territories with acute myocardial injury induced by transthoracic electrical interventions

Figures

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  Figure 1. CMR as a non-invasive tool for assessing regional tissue, systolic and diastolic abnormalities. (a) T1 map with the left ventricle segmented into six territories; orange depicts higher T1 after the intervention, (b) feature tracking strain highlighting the inferoseptal segment, (c) circumferential strain curve of each of the six segments displaying mechanical dispersion after the electrical intervention (pink highlighted inferoseptal segment in (b), red is the global strain curve) and (d) strain rate curve.

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  Figure 2. Study protocol. CMR cardiovascular magnetic resonance exam, SAX short axis stack.

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  Figure 3. Regional impact of electrical interventions on the LV. For the respective slice, the T1 map acquired at 5 h post electrical intervention depicts higher signal (orange) in the septum indicating myocardial injury. This matches the histological samples in which interstitial space is greatest in sample acquired from the septum in comparison to the lateral wall. The polar plots on the bottom row depict the quantitative measurements for each of the six segments in the slice at baseline (green) and 5 h post intervention (red), with the change between timepoints shaded in grey.

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  Figure 4. Ability of CMR feature tracking to discriminate incremental increases of LV interstitial space. Receiver operating curves demonstrate the area under the curve of the regional diastolic and systolic feature tracking strain measurements in comparison to localized samples assessed histologically for interstitial space. Analysis was performed using three cut-offs increasing with more severe myocardial injury.

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  Figure 5. Impact of electrical interventions on the RV. Left: slice positions of the right ventricle (endocardium = yellow, epicardium = blue). Right: circumferential strain at end-systole indicating a worsening in strain (yellow-orange) 5 h after electrical intervention.

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  Figure 6. Summary figure. The illustration highlights the aim of the study and the key findings of global and regional systolic and diastolic dysfunction assessed by CMR feature tracking strain techniques, and of myocardial tissue injury quantified non-invasively by CMR T1 mapping and serology and by invasive histological assessments.