Non-dipping pattern in untreated hypertensive patients is related to increased pulse wave velocity independent of raised nocturnal blood pressure.

BACKGROUND

Non-dipper pattern, characterized by diminished nocturnal decline in blood pressure (BP), is associated with an increase in cardiovascular events. Carotid-femoral pulse wave velocity (CF-PWV) has been accepted as the gold standard measurement of arterial stiffness. CF-PWV is a well-recognized predictor of an adverse cardiovascular outcome with higher predictive value than classical cardiovascular risk factors. In this study, we investigated the association between PWV as the surrogate of arterial stiffness and non-dipper pattern in untreated hypertensive patients.

METHODS

The present study was cross-sectional and observational. Hypertensive patients were diagnosed according to ambulatory BP measurements (mean BP ≥ 130/80 mmHg). Eighty-four hypertensive patients, consulted for initial evaluation of hypertension, were enrolled. CF-PWV as the indicator of arterial stiffness was measured by a validated tonometry system (SphygmoCor). Patients with the history of any cardiovascular disease were excluded from the study.

RESULTS

Fifty-six patients had non-dipper pattern and 28 patients had dipper pattern in the study. Baseline characteristics were not significantly different between the two groups, except the CF-PWV (non-dipper vs dipper; 8.91 ± 2.53 vs 7.66 ± 1.08 m/s, p = 0.002), female gender (55% vs 32%, p = 0.045) and nocturnal BP measurements (for mean BP; 106 ± 11 vs 92 ± 8 mmHg, p < 0.001). Multiple logistic regression analysis including age, gender, BP and PWV measurements, revealed female gender (odds ratio, OR = 5.112, 95% confidence interval, CI 1.282-20.4, p = 0.021), nocturnal mean BP (OR = 1.243, 95% CI 1.107-1.396, p < 0.001) and CF-PWV (OR = 1.992, 95% CI 1.240-3.198, p = 0.004) as the independent predictors of non-dipper hypertensive pattern.

CONCLUSION

Our results suggest that diminished nocturnal decline in BP is independently associated with PWV and nocturnal BP rather than daytime BP. Non-dipper pattern, mainly related to increased PWV and impaired modulation of vascular smooth muscle tone during the night, may justify an increased cardiovascular risk in these patients.