Microvascular wall-to-lumen ratio in patients with arterial hypertension: A randomized controlled exercise trial

Background and aims: High blood pressure is one of the main cardiovascular disease risk factors that contribute to vascular remodeling and dysfunction. We aimed to investigate I) group differences of the retinal microstructure between patients with hypertension and healthy individuals and II) the effects of a high-intensity interval training (HIIT) on hypertension-induced microvascular remodeling in patients with hypertension in a random-ized controlled trial.Methods: Arteriolar and venular retinal vessel microstructure including retinal vessel wall (RVW), lumen diameter and wall-to-lumen ratio (WLR) of 41 hypertensive patients, treated with anti-hypertensive medication, and 19 normotensive healthy controls were screened based on high-resolution fundoscopies. Patients with hy-pertension were randomized to a control group receiving standard physical activity recommendations and an intervention group receiving a supervised and walking-based HIIT for eight weeks. Measurements were repeated after the intervention period.Results: Hypertensive patients showed thicker arteriolar RVW (28.0 +/- 7.7mu vs. 21.4 +/- 4.4mu, p = 0.003) and higher arteriolar WLR (58.5 +/- 14.8 % vs. 42.5 +/- 8.2 %, p < 0.001) compared to normotensive controls. The intervention group showed reductions in arteriolar RVW (beta-3.1 (95 % CI,-4.38,-1.78) p < 0.001) and arteriolar WLR (-5.3 (-10.14,-0.39) p = 0.035) compared to the control group. The intervention effects were independent of age, sex, change in blood pressure and change in cardiorespiratory fitness.Conclusions: HIIT in patients with hypertension improves retinal vessel microvascular remodeling after eight weeks of training. In patients with hypertension, screening retinal vessel microstructure by fundoscopy and monitoring efficacy of short-term exercise treatment are sensitive diagnostic approaches to quantify microvas-cular health in these patients.