Abstract 13054: Longitudinal Strain-Derived Myocardial Work to Reflect the Systolic Performance of Athlete’s Heart

Abstract

Introduction: In athletes, the exercise training-induced enhancement of myocardial contractility is challenging to be captured using conventional echocardiographic parameters due to their load-dependency. Hypothesis: As speckle-tracking echocardiography (STE)-derived myocardial work (MW) is considered to be less dependent on loading conditions than global longitudinal strain (GLS), we hypothesized that it reflects cardiac contractility more reliably, and thus, it represents a robust resting marker of the athlete's heart. Accordingly, we investigated whether MW can capture the supernormal LV systolic performance of swim-trained rats and elite human swimmers even during resting conditions. Methods: Sixteen rats underwent a 12-week swim training program and were compared to controls (n=16). STE was performed to assess GLS, which was followed by invasive pressure-volume (P-V) analysis to measure contractility (slope of end-systolic P-V relationship [ESPVR]). Global MW index (GMWI) was calculated from GLS curves and LV pressure recordings. In the human investigations, 20 elite swimmers and 20 healthy sedentary controls were enrolled. GMWI was calculated through the simultaneous evaluation of GLS and non-invasively approximated LV pressure curves at rest. All subjects underwent cardiopulmonary exercise testing to determine peak oxygen uptake (VO 2 /kg). Results: Exercised rats exhibited higher values of GLS, GMWI, and ESPVR than controls (-20.9±1.7 vs. -17.6±1.9 %, 2745±280 vs. 2119±272 mmHg·%, 3.72±0.72 vs. 2.61±0.40 mmHg/μL, all p<0.001). Ordinary least squares modeling revealed that GLS was predominantly determined by sex and afterload, whereas the major determinants of GMWI were contractility and exercise. In humans, regular exercise training was associated with decreased GLS (-17.6±1.5 vs. -18.8±0.9 %, p=0.002) but increased GMWI at rest (1899±136 vs. 1755±234 mmHg·%, p=0.025). GMWI correlated positively with VO 2 /kg (r=0.53, p<0.001). Conclusions: GMWI precisely reflected LV contractility in a rat model of exercise-induced LV hypertrophy and captured the supernormal systolic performance in human athletes even at rest. Our findings endorse the utilization of MW analysis in the evaluation of the athlete's heart.