3075Global longitudinal strain and mechanical dispersion in the general population aged 50–64 years – results from the echocardiography study of the Swedish CArdioPulmonary bioImage Study (SCAPIS)
Authors: Kylhammar D , Hult L , Blomstrand P , Engstrom G , Johnson J , Ostgren C J , Engvall J 
Published: October 2019

Abstract

Background
The Swedish CArdioPulmonary bioImage Study (SCAPIS) was initiated to improve understanding of underlying mechanisms in order to prevent cardiovascular and pulmonary disease. 30 000 individuals aged 50–64 years, randomly selected from the general population, were included in the study. Six-thousand-eight-hundred of the individuals underwent transthoracic echocardiography.
Global longitudinal strain (GLS) and mechanical dispersion (MD) are novel echocardiographic measures of left ventricular (LV) systolic function and electrical instability reflecting risk for malignant arrhythmia, respectively. Previous studies suggest that the limit of normal for GLS is −16% and that MD >70 ms may be associated with increased risk for malignant arrhythmias. GLS and MD have, however, not before been investigated in a large population-based study.

Purpose
The purpose of this first project within the SCAPIS echocardiography study is to determine the prevalence of impaired GLS and MD in the general population aged 50–64 years.

Methods
GLS and MD, defined as mean peak longitudinal strain of the 18 LV segments and standard deviation of time-to-peak strain for the 18 LV segments, respectively, were analysed using a commercially available software. For group comparisons, the independent-samples t-test, the Mann-Whitney U-test or One Way Analysis of Variance with the Bonferroni post hoc test were performed. Values are mean±standard deviation.

Results
1850 examinations have so far been reviewed, whereof image quality was considered adequate for strain analysis in 1480 individuals (80%). Image quality, assessed as the number of visually assessable LV segments, was better for the second half of the examinations, as compared to the first half (p<0.001). Of the 1480 individuals where GLS and MD were assessed, 51% were women and mean age was 57±4.4 years with no difference in age between the sexes (p=ns). Mean GLS was −20±2% and men had significantly more negative (p<0.001) GLS values than women (−21±2% vs. −19±2%). There was no significant difference (p=ns) in GLS when comparing individuals aged 50–54, 55–59 or 60–64 years, respectively. GLS values were less negative than −16% in 1.9% of the study population. Mean MD was 41±12 ms with no significant difference (p=ns) between the sexes. MD was significantly lower (p<0.001) among individuals aged 50–54 years, as compared to those aged 55–59 or 60–64 years, respectively. MD was >70 ms in 1.6% of the study population.

Conclusions
These preliminary data from the SCAPIS echocardiography study suggest that, in the general population aged 50–64 years, 1.9% have impaired GLS and 1.6% have increased MD, which is possibly associated with a higher risk for malignant arrhythmias. Men had more negative GLS values than women and MD was lower in the lowest age tertile. Further analyses are ongoing.

Acknowledgement/Funding
The Swedish Heart and Lung Foundation. Grants from Linkoping University. ALF-grants from the Swedish government (LIO-700841).