Hypertension and cardiovascular disease
Summary
Over the past 30 years, numerous clinical trials evaluating a variety of different classes of drugs have conclusively shown the benefit of blood pressure reduction in reducing the risk of strokes and cardiovascular mortality. Moreover, such trials have clearly demonstrated that blood pressure is unlikely to be controlled with a single drug and often two or more therapies are required to achieve blood pressure targets.Over the past 30 years, numerous clinical trials evaluating a variety of different classes of drugs have conclusively shown the benefit of blood pressure reduction in reducing the risk of strokes and cardiovascular mortality. Moreover, such trials have clearly demonstrated that blood pressure is unlikely to be controlled with a single drug and often two or more therapies are required to achieve blood pressure targets.
Disappointingly, data from the England Health Survey in 1998 showed that blood pressure control was being achieved in less than 6% of patients. Subsequently, the new General Medical Services (GMS) GP contract has incorporated the audit standard of 150/90 mmHg as one of the key quality targets. Clearly, the government feels that a lot of the blame for a failure to achieve these targets rests with primary care! However, much of the blame must also be shouldered by hypertension specialists and opinion leaders who have designed ever more complicated trials, pitting one class of drug against another and examining benefits in higher and higher risk groups. The overall message, however, could not be simpler – blood pressure lowering, even in moderate amounts, results in significant reductions in cardiovascular mortality. For example, it has been shown that reductions of 10 and 5 mmHg in systolic and diastolic blood pressure, respectively, are associated with a 40% reduction in stroke incidence and a 20% reduction in the incidence of coronary heart disease. Analysis of recent hypertension trials by the Blood Pressure Lowering Treatment Trialists’ Collaboration have shown that reductions in systolic blood pressures of under 5 mm/Hg are associated with significant differences in cardiovascular endpoints.
Recent debates in the hypertension literature have focused on the effects of angiotensin-converting enzyme (ACE) inhibitors beyond hypertension, specifically in terms of preventing cardiovascular events. Whilst such effects may be borne out by future studies, it is important that one should not lose sight of the overwhelming benefit of optimal blood pressure control provided by any of the major classes of antihypertensive agents. To this end, the most recent guidelines of the British Hypertension Society (BHS) have endorsed the ABCD algorithm for blood pressure control. The rationale for such an approach is to make the choice of initial and subsequent hypertensive agents simpler and more logical. It is based on the premise that hypertension at different ages and in different ethnic groups has different underlying mechanisms. Primarily, younger hypertensive patients who are not black are more likely to have over activity of the renin–angiotensin system and are therefore more likely to respond to ACE inhibitors or angiotensin II receptor antagonists. The combination of drugs proposed by the algorithm is supported by a small study that showed patients who responded to an ACE inhibitor (A) were just as likely to respond to a â-blocker (B), but did not respond as well to a calcium-channel blocker (C) or a diuretic (D). Conversely, patients who responded to a calcium-channel blocker were just as likely to respond to a diuretic but not as well to an ACE inhibitor or a â-blocker.
The guidelines therefore recommend an ACE inhibitor (or angiotensin II receptor antagonist) or a â-blocker in young non-black patients as first-line treatment. If blood pressure is not controlled then either a calcium-channel blocker or a diuretic is added. For older or black patients, the opposite approach is recommended. The guidelines also encourage the use of combined preparations to encourage compliance, providing they are cost neutral. In summary, over 30 years of data have established the clear benefit of optimising blood pressure control in hypertensive patients. It is now of paramount importance that these patients reap the clinical benefits of the array of excellent pharmacological agents currently available.
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This Editorial has been written by the specialist opinion leader, Dr Khalid Barakat, Consultant Cardiologist, Heatherwood and Wexham Hospitals NHS Trust, and the , and published in the latest issue of the serial publication, Drugs in Context.
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