Background: The impact of aortic stiffness in the development of coronary microvascular dysfunction in chronic coronary syndrome (CCS) remains unknown. Invasive aortic pressure curves, routinely recorded during coronary angiography, provide an opportunity to assess aortic stiffness through pulse wave analysis and relate to measures of coronary microvascular dysfunction.

Purpose: To investigate the relationship between invasive aortic pulse wave features – such as pulse pressure, augmentation index, and reflection time – and (i) thermodilution-derived indices of coronary flow and (ii) major adverse cardiovascular events (MACE) in patients with CCS.

Methods: CCS-patients were prospectively included the day before coronary angiography. Coronary flow was assessed in the LAD using the thermodilution technique during coronary angiography at rest and during adenosine infusion. Index of microcirculatory resistance (IMR), baseline resistance index (BRI), hyperemic flow velocity (HFV), resting flow velocity (RFV), and microvascular resistance reserve (MRR) were recorded. Aortic pressure waveforms recorded during coronary angiography were analysed using a dedicated software. Pulse pressure, augmentation index, and reflection time (time interval from waveform onset to the reflected wave) were determined. Follow-up was conducted through the population registry, telephone calls and review of medical records. Pulse wave metrics were analysed in relation to indices of microvascular function with linear regression. Skewed variables were log-transformed. Cox regression analyses were used for pulse wave metrics in relation to MACE, defined as death, myocardial infarction or hospitalization due to heart failure.

Results: Three-hundred and eighty-six patients, with median age 68 years (IQR 59-74), including 95 (25%) women, were included in the analysis. Median follow-up was 5.4 years (IQR 3.2–6.6), during which 52 patients experienced a MACE. Pulse pressure was associated with RFV and inversely associated with BRI, and MRR but not with IMR or HFV (Figure 1). Augmentation index was associated with HFV (β = 10 [95% CI 1.6–19]) and RFV (β = 11 [95% CI 1.3 – 20.0]). Reflection time was inversely associated with HFV (β = -0.014 [95% CI -0.026 – -0.003]) and RFV (β = -0.018 [95% CI -0.030 – -0.005]). Pulse pressure was associated with MACE (HR 1.03 [95% CI 1.01 – 1.04]; Figure 2) before but not after adjustment for age and gender (HR 1.01 [95% CI 1-1.03). Augmentation index and reflection time were not associated with MACE (Figure 2).

Conclusions: Pulse pressure derived from invasive aortic pulse wave is associated with higher coronary microcirculatory resting flow velocity, lower microcirculatory coronary resting resistance and lower non-endothelial dependent vasodilatory capacity in the LAD. Furthermore, in patients with CCS, invasive central pulse pressure is associated with MACE in crude analysis but not after adjustments for age and gender.