Systolic pressure is all that matters.

Blood pressure is usually expressed as two com ponents—diastolic and systolic pressures. Systolic hypertension is much more common than diastolic hypertension, and systolic blood pressure contributes more of the huge global disease burden attributable to hypertension than does diastolic pressure. However, there has undoubtedly been confusion about the relative merits of targeting systolic versus diastolic blood pressure, which has led to poor recognition in the wider medical community of the importance of systolic pressure. We propose a simplifi ed view of hypertension for most aff ected patients—ie, those aged over 50 years—whereby the thresholds for the diagnosis and treatment of hypertension can be expressed in one dimension: systolic pressure. Distilling the risk imparted by high blood pressure into a single number will greatly assist in both the communication of an important public-health message to patients and policy makers and in the simplifi cation of treatment targets and thresholds for the physician. The minds of drug innovators will also be focused to develop better ways to treat high systolic pressure. At the moment, high blood pressure in most aff ected people remains inadequately treated and modern drug development remains focused on the wrong target. Observational studies show clear associations between raised systolic or diastolic blood pressure and the risk of cardiovascular disease. However, what these studies have not emphasised is the changing burden of disease attributable to systolic pressure versus that attributable to diastolic pressure. Blood pressure profi les change with increasing age. Systolic pressure rises with age; by contrast, diastolic pressure increases until around age 50 years and falls thereafter—at a time when the risk of cardiovascular disease begins to rise. As a consequence, there is an increased prevalence of high systolic pressure over age 50 years and an almost total disappearance of high diastolic pressure (fi gure). Since more than 75% of people with high blood pressure are over age 50 years, the burden of disease is mainly due to systolic pressure. The use of diastolic pressure for diagnosis and risk stratifi cation in our ageing populations has thus become illogical. In younger people, higher systolic and diastolic blood pressures are mainly caused by an increase in peripheral vascular resistance generated by functional and structural narrowing of the resistance arteries and arterioles. However, as age advances, structural damage and disease in larger conduit arteries becomes a more important determinant of blood pressure. Large artery changes result in arterial stiff ening and a loss of vascular compliance, thereby reducing the buff ering capacity of the arterial system, causing a progressive rise in systolic pressure with age, accompanied by a fall in diastolic pressure and a widening in pulse pressure. Increased pulse pressure is therefore indicative of large artery disease and is also associated with increased cardiovascular risk. However, assessment of systolic pressure is suffi cient to capture this component of risk, since there is hardly ever a situation in which pulse pressure is increased in the context of a normal systolic pressure. Importantly, these large artery structural changes could be irreversible and render the continuing rise in systolic pressure more diffi cult to control. Textbooks of physiology emphasise the constant diastolic load to which the vascular walls are subjected, and historically this focus on diastolic pressure has determined the use of this measure for therapeutic decision making and also as a criterion for inclusion in randomised trials of treatments to lower blood pressure. Simultaneously, systolic pressure was largely ignored and considered to be a part of the natural ageing process, as exemplifi ed by the popular mantra that a systolic blood pressure of 100 plus an individual’s age was to be expected. Illustrative of the eminence of diastolic pressure, as recently as the late 1990s, the fi rst and only major hypertension trial designed to defi ne the optimum treatment target for hypertension focused on diastolic rather than systolic pressure targets. The emergence of systolic hypertension as the major risk factor relates to two major changes: people are living longer and people with hypertension are generally being identifi ed and treated earlier. As a result, severe diastolic hypertension is becoming less of a problem while Lancet 2008; 371: 2219–21