Relating cardiovascular risk to out-of-office blood pressure and the importance of controlling blood pressure 24 hours a day.

Blood pressure exhibits a natural circadian rhythm characterized by a decrease during sleep, then a steep increase in the early morning period followed by higher values throughout the active waking period. Because an excessive early morning surge in blood pressure is associated with an elevated risk for cardiovascular events, it represents a potential therapeutic target in patients with hypertension, especially those already at high risk for such events. Ambulatory blood pressure monitoring (ABPM) is an out-of-office technique that allows assessment of blood pressure control during a 24-hour period, including the morning surge. It is known that 24-hour control based on ABPM is a better predictor of hypertensive target-organ involvement and cardiovascular events than conventional in-office blood pressure measurement. ABPM also reveals that many antihypertensive drugs do not adequately control early morning blood pressure, particularly when given once daily in the morning. There are several effective ways to improve morning blood pressure control. These include using agents with a long pharmacologic half-life; prescribing drug formulations specifically designed to target the morning blood pressure surge when given at bedtime; or increasing dosages to twice daily that of conventional shorter-acting agents.