Determinants of myocardial mechanics in top-level endurance athletes: three-dimensional speckle tracking evaluation

<span class="paragraphSection"><div class="boxTitle">Aims</div>The determinants of systolic function in the performing heart are not completely understood. Aim of the study was to assess the contributors of left ventricular (LV) strain components, using 3D speckle tracking echocardiography (STE) in endurance athletes.<div class="boxTitle">Methods and Results</div>A total of 36 top-level male endurance athletes (AT) and 36 age-matched sedentary normal controls (NC) underwent standard and real-time 3D echocardiography. Global longitudinal strain (GLS), global circumferential strain (GCS), global area strain (GAS), and global radial strain (GRS) were assessed using 3D STE. AT had significantly higher GLS (−22.1 ± 4.4 vs. −18.4 ± 3.5%; <span style="font-style:italic;">P</span> < 0.0001), GCS (−17.9 ± 2.4 vs. −16.0 ± 3.2; <span style="font-style:italic;">P</span> = 0.006), and GAS (−35.5 ± 6.7 vs. −30.2 ± 4.9; <span style="font-style:italic;">P</span> < 0.0001), while GRS did not differ significantly with NC. At separate multiple linear regression analyses, heart rate emerged as independent predictor of GLS (<span style="font-style:italic;">β</span> = −0.37, <span style="font-style:italic;">P</span> < 0.002), GCS (<span style="font-style:italic;">β</span> = −0.32, <span style="font-style:italic;">P</span> = 0.007), GAS (<span style="font-style:italic;">β</span> = −0.37, <span style="font-style:italic;">P</span> < 0.001), and GRS (<span style="font-style:italic;">β</span> = −0.29, <span style="font-style:italic;">P</span> = 0.019); LV mass was independently associated with GLS (<span style="font-style:italic;">β</span> = 0.34, <span style="font-style:italic;">P</span> = 0.009) and GAS (<span style="font-style:italic;">β</span> = 0.41, <span style="font-style:italic;">P</span> < 0.001) but not with GCS and GRS, while diastolic blood pressure predicted GCS (<span style="font-style:italic;">β</span> = −0.46, <span style="font-style:italic;">P</span> < 0.0001), GAS (<span style="font-style:italic;">β</span> = −0.28; <span style="font-style:italic;">P</span> = 0.006), and GRS (<span style="font-style:italic;">β</span> = −0.42, <span style="font-style:italic;">P</span> < 0.001). No independent correlation emerged for body surface area and stroke volume. By replacing LV mass with end-diastolic volume, the latter showed independent association with GCS (<span style="font-style:italic;">β</span> = −0.65, <span style="font-style:italic;">P</span> = 0.028) and with GRS (<span style="font-style:italic;">β</span> = −0.60, <span style="font-style:italic;">P</span> < 0.05).<div class="boxTitle">Conclusion</div>AT have an increased myocardial function at rest when compared with NC, this being elicited mainly by subendocardial and mid-wall fibres. Sinus bradycardia, LV mass, and afterload are independent determinants of supernormal myocardial deformation at rest.</span>

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