Diastolic left ventricular function in relation to the retinal microvascular fractal dimension in a Flemish population

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/m(2), 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/m(2) (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.