Reduction of the blood pressure by 5 mmHg can decrease the risk of stroke by 34 % , of ischaemic heart disease by 21 % , and reduce the likelihood of dementia , heart failure , and mortality from cardiovascular disease .
For example , reducing blood pressure by 5 mmHg ( e.g. from 150\/100 to 145\/95 mmHg ) can decrease the risk of stroke by 34 % and of heart disease by 21 % .