Normalization of global longitudinal strain after a 30-seconds exercise bout in elite athletes
Authors: Verwijs S M , De Bruin-Bon H A C M , Van Hattum J C , Spies J L , Planken R N , Boekholdt S M , Groenink M , Van Den Hoogenband C R , Moen M H , Wilde A A M , Pinto Y M , Jorstad H T 
Published: October 2021

Abstract

Background/Introduction
Transthoracic echocardiography (TTE) is often the first diagnostic imaging modality of choice in athlete care to differentiate between physiological adaptation to sports and pathology. Mechanical strain as outcome measure, i.e. left ventricular (LV) global longitudinal strain (GLS), has been suggested as a tool to detect early signs of myocardial diseases in athletes. However, low or very low rates of myocardial deformation can also be associated with cardiac adaptation to sports. We hypothesize that observing decreased cardiac deformation in elite athletes may be a sign of an outspoken relaxed cardiac state, rather than pathology. Therefore, we investigated whether a short exercise bout can normalize strain values in elite athletes with abnormal resting GLS.

Methods
We prospectively enrolled elite athletes who participated in the ELITE (Evaluation of Lifetime Participation in Intensive Top-level Sports and Exercise) cohort. In short, ELITE is a prospective athlete cohort, which collects medical history, ECG, TTE and cardiac magnetic resonance (CMR) data in elite athletes (Olympic/Paralympic level or comparable). For this analysis, we analysed TTEs of asymptomatic athletes without cardiovascular disease and with a structurally normal heart on CMR. TTE (Vivid, GE) was performed in each athlete according to guidelines at rest. After a short exercise bout, consisting of 20 squats, additional measurements were performed when heart-rate (HR) was comparable to HR during pre-exercise measurements. TTE data was assessed using EchoPAC (GE). Paired t-tests were calculated for functional parameters; boxplots for pre- and post-exercise measurements; and GLS delta (pre- to post-exercise) for each athlete was calculated were plotted; using R. GLS ≥−16% was considered decreased and −16% ≥ GLS &gt;−18% borderline.

Results
Our population comprised 51 athletes (35% women), with a mean age (±SD) of 26.4±5.2 years, and mean BSA of 2±0.3m2. Athletic disciplines consisted of road cycling (n=25), hockey (n=7), swimming (n=5), and 7 miscellaneous sports (n=14). We observed an increase of myocardial deformation after a short bout of exercise: mean GLS delta of 2.6±2% (pre- vs post-exercise GLS: −18.2±2.1% vs −20.8±1.9%; P≤0.001; Figure, A). Furthermore, mean LV stroke volumes were 94±19ml vs 103±23ml (P=0.020), ejection fractions (EF) 57±4% vs 60±4% (P≤0.001), and HR 55±10bpm vs 54±13bpm (P=0.8). Finally, we found a decreased strain in 8 athletes (16%), in 7 of which increased to normal values. Mean delta GLS was 4.5±2.2 (pre- vs post-exercise GLS: −14.9±1.1% vs −19.4±2.7%, P=0.002, Figure, B). The athlete who did not show an increase to normal GLS levels had a decreased LV EF (42%), but showed no other signs of cardiac pathology (MRI, biomarkers, complaints).

Conclusion
In athletes with abnormal GLS at rest, performing a short exercise bout may provide a pragmatic method to separate decreased GLS due to true pathology from sports adaptation.

Funding Acknowledgement
Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Amsterdam Movement Sciences