Myocardial ischemia with non-obstructive coronary arteries (INOCA) is a disease disproportionately affecting women that is associated with a reduced quality of life and an increased risk of adverse cardiovascular events. Coronary microvascular and endothelial abnormalities are suspected to be the underlying causes of INOCA in the majority of patients. Currently, there is no widely accepted noninvasive test for diagnosing coronary microvascular and endothelial dysfunction in affected patients. To that end, recent evidence suggests microvascular function in the peripheral vascular circulation may correspond to coronary endothelial dysfunction. In this study, we tested the hypothesis that women with INOCA have attenuated peripheral microvascular and endothelial function compared to healthy controls.
Methods and Results
We utilized three measures of peripheral arterial function, (1) flow-mediated dilation (FMD), (2) pulse arterial tonometry (PAT) and (3) velocity time integral (VTI), to understand the prevalence of microvascular and endothelial dysfunction in women with INOCA. Our study sample consisted of 32 perimenopausal women presenting with persisting chest pain and a diagnosis of INOCA following catheterization (mean age= 55 ± 6), and we compared them with 46 healthy age-matched healthy women (mean age= 51 ± 5). We found a significant difference in small-vessel endothelial function between the two groups as assessed by PAT, with patients demonstrating reduced function (RHI 2.08 ± 0.72 vs 2.54 ± 0.69, p=0.007) (Figure 1). This difference was statistically significant after correcting for confounders correlated with PAT, including age, body mass index, and hypertension (p=0.027). Small attenuations in brachial vasodilatory function as measured by FMD (Patients, 7.9 ± 3.9 vs controls, 9.3 ± 3.4, p=0.192) and in hyperemic flow velocity as measured by VTI (patients 109 ± 47m vs controls, 128 ± 42m/s, p=0.138) were not significant.
We demonstrated that patients with INOCA have significantly attenuated peripheral microvascular endothelial function compared to healthy controls as assessed by pulse arterial tonometry. Our findings suggest that peripheral and coronary microvascular dysfunction coincide and thus may reflect a systemic nature of vascular dysfunction in women with INOCA.
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