White coat hypertension and carotid atherosclerosis

To investigate further the relationship between atherosclerotic vascular disease and blood pressure, and the phenomenon of white coat hypertension, we performed a cross-sectional study of patients referred for carotid Doppler scanning, to determine the relationship between ambulatory blood pressure monitoring (ABPM) and carotid atherosclerosis. We studied 79 patients (51 men, 28 women) undergoing Doppler ultrasound examination of the carotid arteries: 44 (56%) had evidence of carotid atherosclerosis on Doppler ultrasound examination ("disease group"), whilst 35 (44%) had normal carotid arteries ("controls"). "Adequate" ABPM recordings, defined by > 90% of recordings over the 24 h, were available in 51 patients (30 positive, 21 negative). There were no significant differences in mean daytime, mean night-time or mean 24 h ABPM recordings between those with and without carotid atherosclerosis. Mean manual clinic systolic blood pressure was significantly greater in those with carotid atherosclerosis than in controls (146.7 +/- 25.2 vs 131.1 +/- 35 mmHg, p < 0.005). In patients with carotid atherosclerosis, the first systolic blood pressure ABPM recording was not significantly different from the mean manual clinic recording (mean difference -1.5 mmHg, 95% confidence interval (CI) -7.9 to 4.8 mmHg). The initial diastolic blood pressure ABPM recording was significantly higher than the mean manual recording. Carotid atherosclerosis was identified in 53% of normotensive controls compared with 56% of white coat hypertensives and 75% of persistent hypertensives. One-third (9/27) of the patients with normal carotid arteries did not have nocturnal dipping ("non-dippers") compared with 50% (12/24) of the atherosclerotic patients. This study suggests that carotid atherosclerosis may be associated with white coat hypertension. Our study adds to the body of evidence that white coat hypertension is associated with end-organ damage and is not simply a benign disease. Such patients should be screened for other cardiovascular risk factors and should be monitored for the development of persistent hypertension.