Value of ambulatory blood pressure monitoring: Studies that have used ambulatory blood pressure monitoring techniques have shown that the average 24-h or daytime blood pressure values are more closely related to the end-organ damage associated with hypertension than are isolated office readings.
Importance of blood pressure variability in prognosis: More recently, blood pressure variability, measured as the overall 24-h blood pressure standard deviation, has been shown to have a significant relationship to end-organ damage in hypertensive patients. The potential clinical relevance of blood pressure variability has been strengthened in a recent prospective study. The possible prognostic value of blood pressure variability has practical implications for antihypertensive treatment; it may mean, for example, that the optimal antihypertensive drug should reduce not only the mean 24-h values but also the degree of fluctuation in blood pressure. This is more likely to occur with long-acting drugs, which induce a more balanced reduction in blood pressure throughout the 24 h.
Use of the trough: peak ratio: A proposed measure of a balanced 24-h blood pressure effect is the trough: peak ratio of the blood pressure fall. This ratio can be obtained by clinic blood pressure measurements but ambulatory blood pressure monitoring offers some distinct advantages. One of these advantages is that by revealing the possibility of an excessive fall in blood pressure at the time of the peak effect or an uncontrolled rise at the trough, ambulatory monitoring can also reveal the possible impact of pharmacological treatment on 24-h blood pressure variability.