Coronary flow velocity reserve is reduced in patients with an exaggerated blood pressure response to exercise

Abstract

Coronary artery disease and cardiovascular mortality are increased in patients with an exaggerated blood pressure response to exercise. The exact cause of this increase remains unknown, but previous studies have indicated the presence of endothelial dysfunction in peripheral arteries and subclinical atherosclerosis in these patients. The present study aimed to clarify whether coronary microvascular dysfunction is also present in patients with exaggerated blood pressure response to exercise. A total of 95 patients undergoing exercise testing were consecutively enrolled. Flow-mediated vasodilatation and carotid intima-media thickness were measured using standardized methods. A transthoracic echocardiography examination was performed to measure coronary flow velocity reserve. Patients with an exaggerated blood pressure response to exercise had significantly lower coronary flow velocity reserve than the controls (2.06 (1.91-2.36) vs. 2.27 (2.08-2.72), p = 0.004), and this difference was caused by a reduction in hyperemic flow velocity (57.5 (51.3-61.5) vs. 62.0 (56.0-73.0), p = 0.004) rather than a difference in basal flow (26.5 (22.3-29.8) vs. 26.0 (24.0-28.8), p = 0.95). Patients with an exaggerated blood pressure response to exercise also had a significantly greater carotid intima-media thickness and significantly lower flow-mediated vasodilatation than controls. However, an exaggerated blood pressure response to exercise remained a significant predictor of coronary microvascular dysfunction after adjusting for confounders (OR: 3.60, 95% CI: 1.23-10.54, p = 0.02). Patients with an exaggerated blood pressure response to exercise show signs of coronary microvascular dysfunction, in addition to endothelial dysfunction and subclinical atherosclerosis. This finding might explain the increased risk of coronary artery disease and cardiovascular mortality in these patients.