<qa>  What is the pressure in the bodys main artery?PESCA will evaluate whether: 1 progression of atherosclerosis fatty deposits which narrow the arteries and impair blood flow to vital organs; and 2 central systolic blood pressure the pressure in the bodys main artery, the aorta, when the heart pumps out blood, are reduced in polypill recipients compared to those who continue their usual treatment. Atherosclerosis and central blood pressure are both strongly associated with increased risk of heart attacks and stroke. Atherosclerosis will be assessed by ultrasound scanning of the carotid neck arteries to look at thickness of the artery walls carotid intima media thicknessand plaquesfatty deposits. Direct measurement of central blood pressure is impractical but it will be estimated using a computerised pulsecor device. This uses an inflatable cuff on the arm but provides a detailed recording of the pressure wave as the cuff is deflated which enables pulsecor to calculate central blood pressure. Results from both ultrasound and blood pressure investigations will be reviewed by investigators who do not know whether the subjects have been randomised to the polypill or their usual treatment. 