Fractal analysis provides a global assessment of vascular networks (e.g., geometric complexity). We examined the association of diastolic left ventricular (LV) function with the retinal microvascular fractal dimension. A lower fractal dimension signifies a sparser retinal microvascular network. In 628 randomly recruited Flemish individuals (51.3% women; mean age, 50.8 years), we measured diastolic LV function by echocardiography and the retinal microvascular fractal dimension by the box-counting method (Singapore I Vessel Assessment software, version 3.6). The left atrial volume index (LAVI), e′, E/e′ and retinal microvascular fractal dimension averaged (±SD) 24.3 ± 6.2 mL/m2, 10.9 ± 3.6 cm/s, 6.96 ± 2.2, and 1.39 ± 0.05, respectively. The LAVI, E, e′ and E/e′ were associated (P < 0.001) with the retinal microvascular fractal dimension with association sizes (per 1 SD), amounting to −1.49 mL/m2 (95% confidence interval, −1.98 to −1.01), 2.57 cm/s (1.31–3.84), 1.34 cm/s (1.07–1.60), and −0.74 (−0.91 to −0.57), respectively. With adjustments applied for potential covariables, the associations of E peak and E/e′ with the retinal microvascular fractal dimension remained significant (P ≤ 0.020). Over a median follow-up of 5.3 years, 18 deaths occurred. The crude and adjusted hazard ratios expressing the risk of all-cause mortality associated with a 1-SD increment in the retinal microvascular fractal dimension were 0.36 (0.23–0.57; P < 0.001) and 0.57 (0.34–0.96; P = 0.035), respectively. In the general population, a lower retinal microvascular fractal dimension was associated with greater E/e′, a measure of LV filling pressure. These observations can potentially be translated into new strategies for the prevention of diastolic LV dysfunction.
Wei, F. F., Thijs, L., Melgarejo, J. D., Cauwenberghs, N., Zhang, Z. Y., Liu, C., ... & Staessen, J. A. (2021). Diastolic left ventricular function in relation to the retinal microvascular fractal dimension in a Flemish population. Hypertension Research, 44(4), 446-453. https://doi.org/10.1038/s41440-021-00623-3
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