Hinge point fibrosis is highly prevalent in male elite water polo players
Authors: Verwijs S.M , Van Hattum J.C , Pinto Y.M , Boekholdt S.M , Planken R.N , Groenink M , Van Randen A , Bakermans A.J , Nederveen A.J , Van Den Berg-Faaij A.M , Van Luijk R.D , Moen M.H , Van Den Hoogenband C.R , Wilde A.A.M , Jorstad H.T 
Published: November 2020

Abstract

Background/Introduction
The grey zone between cardiac adaptation to sports and exercise and (early stages of) cardiac pathology constitutes one of the greatest challenges for clinicians involved in the care for (elite level) athletes. Cardiac magnetic resonance imaging (CMR) with late gadolinium enhancement (LGE) is a central diagnostic tool to help differentiate between physiological adaptation and pathology. LGE as seen in myocardial fibrosis has been shown to be a strong predictor for cardiac events. While general (ie. dynamic, static sports) levels of physiological adaptation in athletes have been described, sports-specific CMR findings are essentially lacking, and a systematic sport-specific investigation of LGE is absent.

Purpose
To establish a sports-specific baseline for CMR indices in apparently healthy, male elite water polo players.

Methods
We performed a cross-sectional study in Olympic-level male water polo players. All athletes were asymptomatic and were examined during pre-participation screening. The athletes underwent a comprehensive CMR protocol consisting of long- and short-axis cine imaging, LGE and was performed on two 3 Tesla MRI-scanners (Philips). CMR data were analysed using Circle Cardiovascular Imaging software, and statistical analyses were performed in R.

Results
We screened 24 athletes with a mean age (±SD) of 24.2±3.6 years and body surface area (BSA) of 2.23±0.2 m2. The athletes had indexed end-diastolic volumes of 101.87±33.01 ml and 104.51±43.24 ml, stroke volumes of 140.70±33.23 and 139.44±29.93 ml, and ejection fractions of 56.68±9.07% and 52.98±8.18%, in the left- and right ventricle, respectively. Thirteen athletes (54.2%) had LGE consistent with hinge point fibrosis (HPF+) (one case example presented in the figure). Another two athletes had other patterns of LGE (LGE+). There was a trend towards having a smaller BSA in the LGE+ and HPF+ groups (2.18±0.17 m2 in LGE+ vs 2.31±0.10 m2 in LGE−, p=0.056, and 2.18±0.18 m2 in HPF+ vs 2.29±0.10 m2 in HPF−, p=0.072).

Conclusion
Myocardial fibrosis is present in more than 50% of asymptomatic elite water polo players, with a predilection for the inferior hinge point. Our findings in asymptomatic elite athletes suggest that HPF could be a normal finding in athletes instead of an early sign of pathology. Further studies are warranted to investigate if the HPF is associated with long-term cardiac changes or the development of cardiac pathology.
Figure 1. Late gadolinium enhanced short axis image (left) combined with a polar map of cardiac segmentation (right) depicting the fibrosis pattern in a case of an elite male water polo player alongside the inferior hinge point - as expressed in the percentage of myocardium exceeding the mean signal intensity of reference myocardium plus six-times standard deviation.

Funding Acknowledgement
Type of funding source: Public grant(s) – National budget only. Main funding source(s): Harald Jørstad has received funding from the Amsterdam Movement Sciences and the National Olympic Committee & National Sports Federation