Abstract 11769: Impact of Exercise to the Heterogeneity of Regional Left Ventricular Mechanics

Abstract

Background: The segmental heterogeneity of strain and strain rate in speckle tracking echocardiography are pitfalls in the assessment of left ventricular (LV) mechanics in subjects without LV wall motion abnormality. We aimed to assess the segmental heterogeneity of strain and strain rate at rest and during exercise in healthy subjects. Methods: Twenty-three healthy young volunteers (38 ± 10 years, 13 female) underwent supine bicycle stress testing. Segmental circumferential (Scirc), radial (Srad) and longitudinal (Slong) end-systolic strains and corresponding peak systolic strain rates (SRcirc, SRrad, SRlong) were obtained by STE (EchoPac, GE Medical) for each of 16 LV segments at rest and during exercise. Global values of strain and strain rate components were obtained by averaging segmental values. Results: At rest, all three end-systolic strains showed significant segmental heterogeneity (p < 0.01 for all comparisons). In contrast, peak systolic SRcirc and SRrad had uniform values throughout segments, while SRlong had modest segmental heterogeneity (p = 0.02). During exercise, heart rate (67 ± 10 to 136 ± 19 bpm), systolic blood pressure (124 ± 13 to 170 ± 21mmHg), and biplane ejection fraction (58 ± 4 to 72 ± 5 %), increased significantly (p < 0.001 for all comparisons). At peak exercise, there was a small, but significant increase in global Slong (-19.9 to -23.9%, p < 0.001) and Scirc (-19.6 to -24.2%, p < 0.001) without the change in Srad (46.8 to 41.1%, p > 0.05). On the other hand, all global systolic strain rates almost doubled during exercise; SRcirc from -1.26 to -2.49 s -1 , p < 0.0001; SRrad from 1.82 to 3.26 s -1 , p < 0.0001; SRlong from -1.56 to -2.93 s -1 , p < 0.0001. Importantly, segmental heterogeneity following exercise was not present for all strain and strain rate components (p > 0.05 for all comparisons). Conclusions: Segmental heterogeneity was less pronounced in peak systolic strain rates than in end-systolic strains at rest. Exercise abolished segmental heterogeneity for all strain and strain rate components. Overall, peak systolic strain rate is least affected by segmental heterogeneity and may be more useful in the assessment of LV mechanics than end-systolic strain.