Heckman: ß-Blockers as first-line therapy for hypertension [CMAJ

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ß-Blockers as first-line therapy for hypertension

CMAJ 2000;163(11):1424 [Letters in PDF]

The ¹ recommend against first-line ß-blocker therapy for uncom- plicated hypertension in the elderly and suggest that dihydropyridine calcium-channel blockers are preferable. ß-Blockers had previously been recommended as alternative first-line agents [].² The new recommendation is apparently based on results of the MRC,³ STOP-Hypertension⁴ and Syst-Eur⁵ trials. We question whether the evidence truly supports this change.

In the MRC trial, a preplanned subgroup analysis suggested that ß-blockers are ineffective. However, over 25% of subjects were lost to follow-up, a figure exceeding the number of cardiovascular events in the trial. Furthermore, patients on ß-blockers had significantly higher blood pressure than those on diuretics, raising the possibility that there were unmeasured differences between the groups or that the patients on ß-blockers may have been undertreated despite guidelines for additional agents to achieve blood pressure control.

Uncertainty about ß-blocker effectiveness following the STOP-Hypertension trial arose from the finding that 78% of the subjects on ß-blockers required a second agent to achieve target blood pressure compared with 46% of the subjects on diuretics.² However, ß-blocker doses were not maximized when in fact among older adults with hypertension, ß-blockers at appropriate doses lowered blood pressure to an extent similar to that seen with other agents.^6,7,8,9

Evidence supporting the use of calcium-channel blockers over ß-blockers for hypertension in the elderly is not conclusive. While the Syst-Eur trial demonstrated that use of nitrendipine resulted in fewer cardiovascular events than placebo, there was no ß-blocker group for comparison. Despite a small reduction in the incidence of dementia, further research is needed to determine agents of choice, particularly in light of a recently described association between dementia and older calcium-channel blockers [Evidence].¹⁰

Finally, the STOP-Hypertension-2 trial¹¹ compared first-line ß-blockers and diuretics with angiotensin-converting-enzyme inhibitors and calcium-channel blockers. There were no differences in cardiovascular outcomes. Efficacy for blood pressure lowering, tolerability and the need for additional agents were equivalent among all groups.

Although the case against ß-blockers is weak, ß-blockers at appropriate doses have yet to be compared with other first-line therapies, other than in the MRC trial. The sixth report of the United States Joint National Committee on Prevention, Detection, Evaluation and Treatment of High Blood Pressure recommends an initial approach with diuretics supplemented if necessary with ß-blockers.¹² Perhaps this more accurately reflects the available evidence.

George A. Heckman
Alexandra Papaioannou
Division of Geriatric Medicine
William Parkinson
Department of Rehabilitation
Christopher A. Patterson
Division of Geriatric Medicine
McMaster University
Hamilton, Ont.

References

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