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Antihypertensive therapy and circadian blood pressure profiles: a retrospective analysis utilising cumulative sums
A Stanton1, N Atkins, E O'Brien
1Department of Clinical Pharmacology, Royal College of Surgeons in Ireland, Dublin.
Insights
This study introduces a new method to measure blood pressure changes over 24 hours. Different blood pressure medications significantly alter these daily patterns, with atenolol reducing and captopril increasing blood pressure swings.
Area of Science:
- Cardiology
- Pharmacology
- Biostatistics
Background:
- Previous research on antihypertensive drugs and circadian blood pressure patterns lacks conclusive results.
- A standardized, objective method for quantifying circadian blood pressure profiles has been missing.
Purpose of the Study:
- To investigate the differential effects of first-line antihypertensive agents on circadian blood pressure patterns.
- To introduce and utilize a novel method for quantifying circadian alteration magnitude (CAM).
Main Methods:
- A modified cumulative sums technique was used to calculate CAM, representing the difference between crest and trough blood pressures.
- Retrospective analysis of 24-hour ambulatory blood pressure monitoring data from subjects on no medication or single first-line antihypertensive agents.
- A stratified random sample of 40 subjects from five groups (no medication, bendrofluazide, atenolol, calcium-channel blockers, captopril) was analyzed.
Main Results:
- Subjects on atenolol showed attenuated circadian blood pressure changes compared to untreated subjects.
- Subjects on captopril exhibited significantly increased systolic and diastolic circadian blood pressure swings.
- Bendrofluazide and class 2 calcium-channel blockers did not significantly alter circadian patterns compared to untreated individuals.
Conclusions:
- The modified cumulative sums technique effectively quantifies circadian blood pressure changes.
- Atenolol and captopril have distinct and significant effects on circadian blood pressure variability.
- Further research is warranted to explore the clinical implications of these drug-specific effects on circadian patterns.
Abstract:
The results of previous studies on the effects of antihypertensive agents on circadian blood pressure patterns are inconclusive, possibly due to the lack of a simple, objective, universally accepted method of quantifying circadian blood pressure profiles. In order to investigate for differences in the effects of antihypertensive drugs on circadian changes we utilised a recently described modified cumulative sums technique to quantify circadian alteration magnitude (CAM). CAM is simply calculated as the difference between crest and trough blood pressures, the mean blood pressures of the 6-h periods of highest and lowest sustained pressures respectively. The records from all 24-h ambulatory blood pressure monitoring performed over a 7 year period on subjects either on no medication (1208), or on treatment with a single first-line antihypertensive agent (578), were examined retrospectively. A sample (n = 40) stratified for trough diastolic blood pressure, age and sex was randomly selected from each of the following 5 groups: subjects on no medication, and subjects being treated with bendrofluazide, atenolol, class 2 calcium-channel blockers or captopril alone. Untreated subjects, those on bendrofluazide and those on a class 2 calcium channel blocker had similar circadian patterns. Subjects on atenolol therapy (25.9 +/- 1.7/18.3 +/- 1.3, systolic CAM +/- SE/diastolic CAM +/- SE) had attenuated circadian changes (p < 0.05) when compared to the untreated group (29.8 +/- 1.8/23.6 +/- 1.1), while those on captopril (34.9 +/- 2.4/25.7 +/- 1.8) exhibited markedly increased systolic and diastolic circadian blood pressure swings, which differed from those of the atenolol treated group (p < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)