A Novel Measure of the Power of the Morning Blood Pressure Surge From Ambulatory Blood Pressure Recordings

Geoffrey A. Head, Kanella Chatzivlastou, Elena V. Lukoshkova, Garry L. Jennings and Chris M. Reid

Abstract

Background

We defined a new measure of the morning blood pressure (BP) surge (MBPS) that is derived by the product of the rate of morning rise (RoR) and the amplitude (day–night difference) giving an effective “Power” of the BP rise (BP_Power). We applied this method to determine whether morning BP_Power is different in hypertensives compared to normotensives, males compared to females or altered by antihypertensive treatment.

Methods

BP_Power, RoR, and day–night amplitude were calculated using a double logistic fit of 691 ambulatory recordings.

Results

Ambulatory recordings from untreated male and female subjects showed that upper quartile (distributed by day BP, n = 100) had a 92% greater BP_Power (P < 0.001) than the lower quartile subjects (n = 100) due to both a faster RoR and greater amplitude. Males had a 29% greater BP_Power than females (P = 0.003). Untreated hypertensives and white coat hypertensives showed a greater morning BP_Power (+158% and +86%, respectively) compared to matched normotensives. Subjects taking calcium channel blockers and diuretics alone or in combination with angiotensin receptor blockers had lower morning BP_Power than those on angiotensin converting enzyme (ACE) inhibitors or angiotensin receptor antagonists alone.

Conclusions

A new measure of the MBPS, BP_Power which is based on a mathematical estimate of the rate and amplitude of the rise, is higher in hypertensives, white coat hypertensives, and is modifiable by some specific antihypertensive therapies suggests that it may be theoretically useful to highlight those subjects at greatest risk of cardiovascular events and for determining the most benefit of antihypertensive therapy.

American Journal of Hypertension (2010). doi:10.1038/ajh.2010.126