Background: White coat hypertension (WCH) is related to target organ damage and increased cardiovascular risk. Arterial elastic properties and urinary protein excretion are determinants of cardiovascular performance and predictors of outcomes. We investigated whether office blood pressure (BP) is a better determinant of arterial and renal function than the ambulatory BP in WCH patients.
Methods: We studied 440 consecutive untreated non-diabetic patients with WCH (office BP >140/90 mmHg, mean daytime ambulatory BP <135/85 mmHg). Arterial function was evaluated with carotid-femoral pulse wave velocity (cfPWV), an index of aortic stiffness, and aortic augmentation index (AIx), a composite marker of aortic stiffness and wave reflections. In 24-hour urine, albumin excretion and albumin/creatinine ratio (ACR) were measured as markers of glomerular function and urinary α1-microglobulin was measured as a marker of renal tubular function.
Results: In univariate analysis, office systolic BP correlated significantly with cfPWV (r=0.245, P<0.001), AIx (r=0.31, P<0.001), albumin (r=0.134, P=0.005), ACR (r=0.199, P<0.001) and α1-microglobulin (r=0.118, P=0.013). In contrast, mean ambulatory systolic BP did not correlate with arterial function or urinary proteins (all P>0.5). Hierarchical multilevel linear regression analysis showed that office systolic BP is an independent determinant of cfPWV (P=0.050), AIx (P=0.029), albumin (P=0.002) and ACR (P=0.001) and has a borderline association with α1-microglobulin (P=0.088).
Conclusions: In non-diabetic WCH individuals, office systolic BP is an independent predictor of aortic elastic properties and urinary protein excretion, whereas ambulatory BP is not. This finding suggests that office BP may be a marker of cardiovascular risk in subjects with WCH.
Keywords: Albuminuria; Aortic stiffness; Pulse wave velocity; Wave reflections; White coat hypertension; α1-Microglobulin.
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