Comparison of the ambulatory blood pressure with the clinical blood pressure and electrocardiographic left ventricular hypertrophy

Background : This study compared the results of 24 hour ambulatory blood pressure monitoring with the clinical blood pressure measurements, and we investigated the relationship of the blood pressure measurement and left ventricular hypertrophy, as determined by routine 12 lead electrocardiography. Methods : We studied 204 healthy adults with no prior history of heart disease or antihypertensive medication. The clinic blood pressure was measured 3 times and the average was taken. We compared the clinic blood pressure with the daytime blood pressure of the 24 hour ambulatory blood pressure monitoring, and we compared the blood pressure with the sum of the voltage of the S wave on V1 and the R wave on V5. Results : The average of the daytime ambulatory blood pressure of all the patients was 135.33± 13.73 mmHg for the systolic pressure and 86.55±10.14 mmHg for the diastolic pressure. The average of the clinic blood pressure measurement was 140.10±17.41 mmHg for the systolic pressure and 88.84 ±10.14 mmHg for the diastolic pressure. The clinic blood pressure averaged higher than the daytime ambulatory blood pressure by 5 mmHg on the systolic pressure and 2 mmHg on the diastolic pressure (p<0.001). The normal ambulatory blood pressure limits were estimated as those that best correlated with 140/90 mmHg at the clinic. The estimated value was 135/87 mmHg for the daytime ambulatory blood pressure (p<0.001). The incidence of white coat hypertension was 10.8%. The sum of the voltage on electrocardiography showed a positive linear relationship with all the blood pressure measurements. The daytime systolic blood pressure showed the strongest correlation with the 24 hour ambulatory blood pressure monitoring (r=0.283, p<0.001). Conclusions : We found a linear relation and we analyzed the differences between the clinical and 24 hour ambulatory blood pressure. A daytime ambulatory blood pressure value of 135/87 mmHg was a suitable upper normal limit for the corresponding cutoff value of the clinic blood pressure. Left ventricular hypertrophy showed the strongest relationship with the daytime systolic blood pressure among the results of the 24 hour ambulatory blood pressure monitoring.(Korean J Med 72:181-190, 2007)