Morning rise, morning surge and daytime variability of blood pressure and cardiovascular target organ damage. A cross-sectional study in 743 subjects.

OBJECTIVE

To evaluate in a large population the relationship between cardiovascular target organ damage and values of the night-to-morning rise of systolic blood pressure (MR-BP), the morning surge of BP at the moment of rising (BP surge) and daytime BP variability (standard deviation [SD] of daytime BP).

METHODS

This was a cross-sectional study, evaluating 743 subjects, aged 30-75 years, 416 female, with normal renal function and no previous cardiovascular events. The population included: I-174 patients with type 2 diabetes, II-317 hypertensive patients with ongoing treatment over at least the previous 6 months, III-127 hypertensive patients untreated in the last 6 months, IV-125 healthy normotensive subjects. All underwent 24-hour ambulatory BP monitoring to calculate MR-BP, BP surge and SD of daytime BP. Target organ evaluation included: pulse wave velocity (PWV) (an indicator of aortic stiffness) in 711 subjects, left ventricular mass index (LVMI) in 185 subjects and 24-hour albuminuria in 239 subjects.

RESULTS

In the population as a whole, BP surge, MR-BP and SD of daytime BP correlated significantly with PWV (r = 0.434, p < 0.0001; r = 0.126, p < 0.001; 0.337, p < 0.001, respectively), with LVMI (r = 0.447, p < 0.0001; r = 0.307, p < 0.001; 0.162, p < 0.05, respectively) and to a lesser degree with albuminuria (r = 0.126, p < 0.05; r = 0.083, NS; 0.082, NS, respectively). In the upper quintile of distribution of BP surge, the percentage of cases with abnormal PWV (>12 m/s) (21%), cardiac hypertrophy (53 %) and microalbuminuria (47 %) was significantly greater (p < 0.03) than that observed in the lower quintile (1%, 14% and 27%, respectively). BP surge correlated more strongly with indices of target organ damage than did MR-BP or SD of daytime BP, independently of night-time BP and nocturnal BP fall.

CONCLUSIONS

In this large population, MR-BP, BP surge and daytime BP variability are strongly correlated with target organ damage severity, and are probably related to organ deterioration. Of the three, morning surge of BP at the moment of rising is more strongly related to organ damage than MR-BP, perhaps because unlike MR-BP, BP surge is independent of night-time BP values.