"Our results suggest that cumulative blood pressure load is an independent predictor of cardiovascular events and should be used in future cardiovascular risk prediction algorithms," the authors, led by Nelson Wang, MD, George Institute for Global Health, Sydney, Australia, conclude.
The study was published online in the Journal of the AmericanCollege of Cardiology on September 12.
The researchers explain that the management of hypertension has traditionally centered around blood pressure measurements taken at a single timepoint, with adequate control defined as those measurements being below a predefined target threshold.
However, this approach fails to recognize blood pressure as a continuous measure that fluctuates over time and does not acknowledge that the most recently recorded measurement may not reflect previous blood pressure control.
More recently, studies have defined the time a patient spends below blood pressure target, or TIme at TaRgEt (TITRE), as a novel marker of cardiovascular risk that is independent of mean blood pressure.
Although TITRE has the added advantage of incorporating duration of control, it is unable to characterize the magnitude of blood pressure elevation, the researchers note.
They point out that an optimal measure as a risk factor for cardiovascular disease would account for both the magnitude and duration of elevated blood pressure.
Such a measure is cumulative blood pressure load, defined as the area under the curve (AUC) expressed in units of mm Hg by time.
The only prior study of this measure was small and retrospective and calculated cumulative blood pressure load from ambulatory blood pressure monitoring estimated over a short (24-hour) period.
Therefore, the aim of the current study was to estimate the association between cumulative systolic blood pressure load over a longer period (24 months) and subsequent major cardiovascular events.
To do this, the researchers conducted a post-hoc analysis of 9338 patients with type 2 diabetes in the ADVANCE-ON study.
Cumulative systolic blood pressure load was defined as the AUC for systolic blood pressure values above 130 mm Hg divided by the AUC for all measured systolic blood pressure values over a 24-month exposure period.
Over a median 7.6 years of follow-up, 1469 major cardiovascular events, 1615 deaths, and 660 cardiovascular deaths occurred.
Results showed that each one standard deviation increase in cumulative systolic blood pressure load was associated with a 14% increase in major cardiovascular events, a 13% increase in all-cause mortality, and a 21% increase in cardiovascular death.
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