In a population of elderly patients with hypertension, average blood pressure variability was found to decline during the 2 years following the initiation of antihypertensive medication, according to research published in the Journal of the American Heart Association.

Using estimates from recordings of ambulatory blood pressure monitoring, researchers conducted a post hoc analysis to evaluate the impact of blood pressure-lowering treatment on systolic blood pressure variability. Data were collected from a subgroup of participants in the Second Australian National Blood Pressure study. Participants in the post hoc analysis (n=496) were ≥65 years of age and had 24-hour ambulatory blood pressure recordings available at baseline and follow-up (median, 2 years; average ambulatory blood pressure: baseline, 149/83 mmHg; follow-up, 136/76 mmHg). A decline in weighted day-night ambulatory systolic blood pressure variability was noted over the follow up period (interquartile range, 1.9-2.1 years; mean, 0.60±3.28 mmHg; 95% CI, -0.89 to -0.31; P <.001). This change was positively associated with a change in systolic blood pressure from baseline to follow up. An observed annual rate of decline of -0.37±1.95 mmHg in weighted day-night ambulatory systolic blood pressure variability was also noted (95% CI, -0.54 to -0.19). Overall, 63% of participants had a similar level of ambulatory systolic blood pressure variability — either stable, high, or low — at baseline and follow up. A total of 24% and 13% of patients experienced a change in ambulatory systolic blood pressure variability from high to low and from low to high, respectively, while taking antihypertensive medication.

A total of 96 patient included in the post hoc analysis died following the final ambulatory blood pressure measurement. Of these, 49 deaths were due to cardiovascular causes. Increases per millimeters of mercury in weighted day-night ambulatory systolic blood pressure variability measurements at both baseline and follow up were found to predict all-cause and cardiovascular mortality, independent of systolic blood pressure at baseline. No significant association between mortality and change in weighted day-night systolic blood pressure variability over time was noted (all-cause mortality  hazard ratio, 0.98; 95% CI, 0.88-1.09; cardiovascular mortality, hazard ratio, 0.95; 95% CI, 0.82-1.10).

The risk for all-cause and cardiovascular mortality was found to be higher in participants who had high ambulatory systolic blood pressure variability at baseline, compared with participants who had a consistently low weighted day-night variability.

The change in weighted day-night ambulatory systolic blood pressure variability during the follow-up period was found to be positively related to change in 24-hour ambulatory systolic blood pressure, being a man, and being an active smoker.

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Study limitations include the use of a single 24-hour ambulatory blood pressure measurement at baseline and follow up, the lack of data regarding participants’ blood pressure, blood pressure variability, and use of antihypertensive medications, and the inability to examine the effect of beta- or calcium channel blockers on blood pressure variability.

“Our results fill the information gap regarding the relationship of [blood pressure variability] and changes associated with [blood pressure]-lowering treatment to subsequent mortality,” the researchers concluded. 

Reference

Chowdhury EK, Nelson MR, Wing LMH, et al; on behalf of the Second Australian National Blood Pressure Study Group. Change in blood pressure variability among treated elderly hypertensive patients and its association with mortality. J Am Heart Assoc. 2019;8(21):e012630.