Microvascular Dysfunction in Non-Diabetic Hypertensive Patients Is Related to Dyslipidaemia and Glucose Intolerance: Results From the Doxazosin Ramipril Study

Objective: Microvascular dysfunction relates to increased cardiovascular risk in type 2 diabetes and in the metabolic syndrome. Disturbances in microvascular function are multifactorial, and both low HDL-cholesterol (HDL) and glucose intolerance are important mediators. However, their importance in relation to microvascular function in non-diabetic hypertension is not well studied. Design and method: 71 patients with untreated hypertension (mean BP 154/93 mm Hg) without coronary heart disease were included. The subendocardial viability ratio (SEVR) was calculated by pulse wave analysis (SphygmoCor). Skin microvascular function was assessed by laser Doppler fluxmetry and iontophoresis of acetylcholine (ACh) and sodium nitroprusside (SNP), and by local heating. Glucose tolerance was estimated by the triglyceride (TG) glucose index (TyG, ln fasting plasma glucose (mg/dL) x triglycerides (mg/dL)/2), and by the TG/HDL ratio. Results: Fasting LDL-cholesterol (LDL), HDL and TG 3.48 ± 0.92, 1.40 ± 0.40 and 0.96 0.61–1.33 mmol/L, respectively. Mean glucose was 5.40 ± 0.55 mmol/L, TyG 6.74 ± 0.59, and median TG/HDL ratio 0.65 0.43–1.18. Ach peak flux (mean 42.4 ± 29.8 PU) related to HDL (r = 0.27, P = 0.025). Peak flux by local heating (85.4 ± 43.7 PU) related to HDL (r = 0.29, P = 0.017) and inversely to the LDL/HDL ratio (r = –0.29, P = 0.019). Ach peak flux was inversely related to log(TG/HDL) ratio (r = –0.29, P = 0.016) and tended to relate to TyG (r = –0.23, P = 0.065), while responses to SNP and local heating did not. SEVR (mean 169 ± 29 %) was inversely related to LDL (r = –0.25; P = 0.041), but not to HDL (r = –0.05; P = 0.69). SEVR did not relate to TyG or to log(TG/HDL) ratio. Conclusions: Skin microvascular dysfunction was related to low HDL and to glucose intolerance, whereas coronary microvascular dysfunction was related to increased LDL. Maximum reactive hyperaemia by local heating is a robust method to evaluate skin microvascular function in non-diabetic hypertension. As for patients with type 2 diabetes and the metabolic syndrome, early microvascular dysfunction can be detected in non-diabetic hypertensive patients, and predict cardiovascular risk.