1 What are the cardiovascular risks of
hypertension?
Aroon Hingorani
The risk of death, stroke and coronary heart disease (CHD)
increases continuously with increasing BP with no evidence of a
threshold. The excess risk of stroke and CHD associated with BP
differences of varying degrees is illustrated in Table 1.1.
TTaabbllee 11 .. 11 EEffffeecctt ooff aa ssuussttaaiinneedd ddiiffffeerreennccee iinn BBPP oonn rriisskk ooff ssttrrookkee aanndd
CCHHDD
DDiiffffeerreennccee iinn uussuuaall %% iinnccrreeaassee iinn rriisskk ooff
SSBBPP ((mmmmHHgg)) DDBBPP ((mmmmHHgg)) SSttrrookkee CCHHDD
9 5 34 21
14 7.5 46 29
19 10 56 37
Meta-analysis of outcome trials shows that the reduction in
risk achieved by antihypertensive treatment is approximately
constant whatever the starting BP. Antihypertensive treatment
producing a 5–6mmHg fall in DBP results in an approximately
36% reduction in stroke and a 16% reduction in CHD. Greater BP
lowering would be expected to achieve greater risk reductions.
Although the observed reduction in stroke risk from intervention
trials is commensurate with that predicted by observational
studies, the observed reduction in CHD risk is less than that
expected (see Table 1.2). The reason for this discrepancy is
unclear but might reflect: a clustering of additional cardiovascular
risk factors (for example diabetes and hypercholesterolaemia) in
hypertensive subjects; an adverse effect of some antihypertensive
drugs (e.g. thiazides and βblockers) on plasma lipids; or the
effect of pre-existing end-organ damage.
TTaabbllee 11 .. 22 RReedduuccttiioonnss iinn ssttrrookkee aanndd CCHHDD rriisskk rreessuullttiinngg ffrroomm aa
55 – – 66 mmmmHHgg rreedduuccttiioonn iinn BBPP
RReedduuccttiioonn iinn rriisskk ((%%))
EExxppeecctteedd OObbsseerrvveeddStroke 35–40 31–
CHD 20–25 8–