Exercise Strain Rate Imaging Demonstrates Normal Right Ventricular Contractile Reserve and Clarifies Ambiguous Resting Measures in Endurance Athletes

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Abstract

Background

The significance of reduced right ventricular (RV) deformation reported in endurance athletes (EAs) is unclear, highlighting the ambiguities between physiologic RV remodeling and pathology. The aim of this study was to test the hypothesis that RV functional reserve would be normal in EAs despite reduced deformation measures at rest.

Methods

Forty EAs and 15 nonathletes (NAs) performed maximal incremental exercise with simultaneous echocardiographic measures of RV function. Two-dimensional (2D) and color-coded Doppler acquisitions were used to quantify peak systolic strain and strain rate (SRs) for the basal, mid, and apical RV free wall. A second surrogate of contractility, the RV end-systolic pressure-area relationship, was calculated from the tricuspid regurgitant velocity and the RV end-systolic area. Changes in multiple measures obtained throughout exercise were used to assess the affect of exercise on RV contractility.

Results

Compared with NAs at rest, basal RV strain and SRs were reduced in EAs, with good agreement between 2D and Doppler methods. During exercise, there was a strong linear correlation between heart rate and global SRs (r = −0.74 and r = −0.84 for Doppler and 2D methods, respectively, P < .0001), which was similar for EAs and NAs (P = .21 and P = .97 for differences in mean regression slopes by Doppler and 2D echocardiography, respectively). Exercise-induced increases in the RV end-systolic pressure-area relationship were also similar for EAs and NAs (P = .42). There was a strong correlation between RV global SRs and the RV end-systolic pressure-area relationship during exercise (r = 0.71, P < .0001).

Conclusions

Comparable RV contractile reserve for EAs and NAs suggests that the lower resting values of RV in EAs may represent physiologic changes rather than subclinical myocardial damage.

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