• Left ventricular hypertrophy

To the Editor: Simpson et al show that lowering blood pressure in people with blood pressure considered to be in the ‘normal range’ (122 mm Hg systolic and 70 mm Hg diastolic) reduces the magnitude of left ventricular hypertrophy.1 They conclude that further work is needed to see if blood pressure reduction among individuals with normal values leads to a reduction in cardiovascular disease events. However, further work is not required because it already exists.

Law et al have summarised the results of randomised trials of blood pressure reduction on coronary heart disease events and stroke stratified according to the pre-treatment blood pressure of the individuals included in the trials.2 Figure 5 in this paper (http://www.wolfson.qmul.ac.uk/epm/publications/web/bptrial/figs/figure5.pdf) shows that blood pressure reduction among individuals with average or low blood pressure reduces the risk of heart disease and stroke to the same proportional extent as in individuals with higher pre-treatment blood pressure. This is consistent with the expectation from cohort studies3 which show a constant proportional relationship between the risk of heart disease or stroke and diastolic or systolic blood pressure. Within the physiological range of blood pressure, there is no threshold level below which the risk of cardiovascular disease ceases to decline with further reductions in blood pressure.

The results on left ventricular hypertrophy reported by Simpson et al support the recommendation to reduce blood pressure in all individuals at risk of cardiovascular disease regardless of starting blood pressure.2 4