Abstract
AIMS: In asymptomatic athletes, abnormal exercise test (ET) results have a poor positive predictive value. It is unknown whether abnormal ET results in the absence of obstructive coronary artery disease (CAD) are related to coronary microvascular dysfunction. It is also unknown whether they should be considered false-positive ET results or a consequence of physiological adaptation to sport. In our study, we evaluated whether athletes with abnormal ET results and documented myocardial ischaemia in the absence of obstructive CAD have an attenuated microvascular function and whether coronary microvascular dysfunction is related to endothelial dysfunction. METHODS AND RESULTS: Nine athletes with concordant abnormal ET and myocardial perfusion scintigraphy (MPS) results without obstructive CAD were compared with age- and gender-matched individuals with a low-to-intermediate a priori risk of CAD. Coronary flow reserve was assessed by Rubidium-82 positron emission tomography (PET) imaging. Endothelin‑1 concentrations were measured to evaluate endothelial function. Coronary flow reserve was significantly lower in athletes (3.3 ± 0.8 versus 4.2 ± 0.6, p = 0.014 respectively). Endothelin‑1 levels were significantly higher in athletes (1.3 ± 0.2 pg/ml versus 1.0 ± 0.2 pg/ml, p = 0.012 respectively). There was no correlation between endothelin‑1 concentrations and mean global coronary flow reserve (r = 0.12). CONCLUSION: Athletes with abnormal ET and MPS outcomes indicative for myocardial ischaemia and no obstructive CAD have a lower coronary flow reserve compared with non-athletes with low-to-intermediate a priori risk of CAD, suggesting an attenuated coronary microvascular function. Higher endothelin‑1 concentrations in athletes suggest that endothelial-dependent dysfunction is an important determinant of the attenuated microvascular function.