The Measurement of blood pressure by a doctor may trigger a pressor response, so there are marked differences between office and ambulatory or self-measured blood pressure and the subjects may misdiagnosed as hypertensives and receive unneccesary medication. The study is designed to evaluate the charicteristic of white coat hypertension, the degree of white coat effect and the relationship between the white coat hypertension and persistent hypertension.

Thirteen patients with office hypertension receiving no medication, were recruited from 434 patients experienced in ambulatory blood pressure. Past history, physical examination, office blood pressure, 12-channel standard electrocardiography, chest X-ray, plasma lipid battery, echocardiography and 24-hr ambulatory blood pressure monitoring with BP3 MEDIANA were performed.

1) White coat hypertensive patients were 13 of 434 patients(2.99%) who were performed 24-hr ambulatory blood pressure monitoring. The mean age was 45±12 years with 6 men and 7 women and rage of age was 26-65 years.

2) The lipid battery, chest X-ray and 12-channel standard electrocardiographty showed no significant finding.

3) The LV mass index was 90.7±11.0g/m³ but one of 8 who performed echocardiography showed concentric hypertrophty.

4) The LV ejection traction was 60.8±8.7% which normal range.

5) The mitral flow velocity parameters were E velocity 0.71±0.14m/sec, A velocity 0.54±0.24m/sec, E/A ratio 1.6±0.8, mitral valve deceleration time 214±27.6msec and isovolumic relaxation time 104±11.4msec but one of 8 showed LV relaxation abnormality.

6) The mean office systolic blood pressure was 159±13.8mmHg, mean office diastolic blood pressure 101±9.0mmHg, 24-hr mean ambulatory systolic blood pressure 128±4.9mmHg and 24-hr diastolic bliid pressure 82±8.6mmHg.

7) The night day ratio of systolic blood pressure was 0.93±0.06 and the night day ratio of diastolic blood pressure was 0.92±0.06 suggestive of blunted diurnal variation. The Dipper were 5 of 13 patients(38.5%) and the non-Dipper were 8 of 13 patients(61.5%).

8) Two of 13 white coat hypertensives were diagnosed as persistent hypertensives in follow-up periods and antihypertensive drug had been initiated.

White coat hypertension can be diagnosed by 24-hr ambulatory blood pressure monitoring. The influence of white coat effect to cardiovascular system was not established. Sixty-two percent of white coat hypertensives showed blunted diurnal variation in 24-hr ambulatory blood pressure monitoring and two of 13 were diagnosed as persistent hypertensives in our F/U study, so white coat effect cannot be merely innocent and need strict evaluation and regular follow-up.