The role of HIF-1α, VEGF and obstructive sleep apnoea in the development of coronary collateral circulation

Abstract

Introduction Intermittent hypoxia (IH) in obstructive sleep apnoea (OSA) confers cardioprotection by enhancing coronary collateral circulation (CCC) development, decreasing myocardium vulnerability to hypoxia and ischaemia. The main objective was to assess whether hypoxia inducible factor-1α (HIF-1α) and vascular endothelial growth factor (VEGF) play a role in the development of CCC in patients with OSA. Methodology A total of 44 patients with reported collaterals on angiography were selected as cases, with 21 patients not having a CCC recruited as controls. All patients underwent ambulatory polysomnography to test for the presence of OSA. Blood samples for HIF-1α and VEGF levels were taken. The development of CCC was classified according to the Rentrop Score. Results This study failed to confirm a relationship between the development of CCC and the presence of OSA ([absence/presence, p=0.47], [severity, p=0.44], [mild/moderate versus moderate/severe, p=0.27] and [AHI, p=0.21]), with a non-significant odds ratio of 2.17±1.61 (p=0.21). HIF-1α increased with increasing Rentrop Score (p=0.04), but was not related to the presence or absence of OSA. However, HIF-1α levels in moderate/severe OSA were positively correlated with Rentrop Score (p=0.02), while no/mild OSA patients showed no correlation. VEGF levels did not differ significantly with Rentrop Score or OSA severity. Conclusion This is the first study to date that links OSA, CCC, and plasma HIF-1α and VEGF levels. Significantly, augmented HIF-1α in moderate/severe OSA patients might be an important mediator in the development of CCC, but not in patients with no/mild OSA.