Key result
Increased mechanical dispersion linked to ~69% greater sudden arrhythmic death risk and higher LV fibrosis.
Why the study?
Prior studies linking GLS and MD to SCD presumed cardiac causes from EMS records or death certificates rather than gold-standard autopsies.
Does mechanical dispersion and LV-GLS on pre-mortem echocardiography discriminate between arrhythmic and non-arrhythmic sudden cardiac death?
Observational (n=65)
No
Does mechanical dispersion and LV-GLS on pre-mortem echocardiography discriminate between arrhythmic and non-arrhythmic sudden cardiac death?
Mechanical dispersion on speckle-tracking echocardiography is a non-invasive surrogate for myocardial fibrosis that can independently discriminate true arrhythmic sudden death from non-arrhythmic causes better than LVEF.
Answers are grounded in this paper and cite their sources.
May refine arrhythmic SCD risk assessment beyond LVEF; leaves open prospective validation before clinical adoption.
Background: Global longitudinal strain (GLS) and mechanical dispersion (MD) by speckle-tracking echocardiography can predict sudden cardiac death (SCD) beyond left ventricular ejection fraction (LVEF) alone. However, prior studies have presumed cardiac cause from EMS records or death certificates rather than gold-standard autopsies. Objectives: We sought to investigate whether abnormal GLS and MD, reflective of underlying myocardial fibrosis, are associated with autopsy-defined sudden arrhythmic death (SAD) in a comprehensive postmortem study. Methods: We identified and autopsied all World Health Organization-defined (presumed) SCDs ages 18-90 via active surveillance of out of hospital deaths in the ongoing San Francisco POstmortem Systematic InvesTigation of Sudden Cardiac Death (POST SCD) Study to refine presumed SCDs to true cardiac causes. We retrieved all available pre-mortem echocardiograms and assessed LVEF, LV-GLS, and MD. The extent of LV myocardial fibrosis was assessed and quantified histologically. Results: Of 652 autopsied subjects, 65 (10%) had echocardiograms available for primary review, obtained at a mean 1.5 years before SCD. Of these, 37 (56%) were SADs and 29 (44%) were non-SADs; fibrosis was quantified in 38 (58%). SADs were predominantly male, but had similar age, race, baseline comorbidities, and LVEF compared to non-SADs (all p>0.05). SADs had significantly reduced LV-GLS (median: -11.4% versus -18.5%, p=0.008) and increased MD (median: 14.8 ms versus 9.4 ms, p=0.006) compared to non-SADs. MD was associated with total LV fibrosis by linear regression in SADs (r=0.58, p=0.002). Conclusion: In this countywide postmortem study of all sudden deaths, autopsy-confirmed arrhythmic deaths had significantly lower LV-GLS and increased MD than non-arrhythmic sudden deaths. Increased MD correlated with higher histologic levels of LV fibrosis in SADs. These findings suggest that increased MD, which is a surrogate for the extent of myocardial fibrosis, may improve risk stratification and specification for SAD beyond LVEF. PERSPECTIVES: Speckle tracking echocardiography parameters, in particular mechanical dispersion, may be considered as a non-invasive surrogate marker for myocardial fibrosis and risk stratification in SCD.
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Tastet et al. (2023) conducted an observational in Presumed Sudden Cardiac Death (SCD) (n=65). Increased mechanical dispersion was evaluated on Autopsy-defined sudden arrhythmic death (SAD) (OR 1.69, 95% CI 1.06-2.68, p=0.03). Increased mechanical dispersion was independently associated with autopsy-confirmed sudden arrhythmic death (OR 1.69) and correlated with higher histologic levels of left ventricular fibrosis.
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