Background: A low diastolic blood pressure has been associated with increased cardiovascular risk. The following proposed mechanisms underlie this phenomenon: a low diastolic pressure that compromises coronary blood flow, a low diastolic pressure that is due to deteriorating health, and a low diastolic pressure that is a consequence of stiffening of the large arteries. Atherosclerosis may be the link between stiffening of the arteries, a low diastolic pressure, and an increased cardiovascular risk.
Objective: To study whether a low diastolic blood pressure in older subjects is a reflection of atherosclerosis.
Methods: The Rotterdam (the Netherlands) Study is a population-based follow-up study of 7983 subjects (age, > or = 55 years) who are living in the suburb of Ommoord of Rotterdam. Baseline measurements included ultrasonographic evaluation of the carotid arteries, measurement of blood pressure, and determination of other cardiovascular risk factors. The main cross-sectional analyses were performed among 930 subjects who currently were not using blood pressure-lowering drugs.
Results: A J-shaped association of the intima-media thickness of the common carotid artery with diastolic blood pressure was found with a nadir from 60 to 69 mm Hg. The intima-media thickness was increased in subjects with a diastolic pressure that was less than 60 mm Hg compared with that in subjects with a diastolic pressure that was between 60 and 69 mm Hg (a difference of 0.033 mm [95% confidence limits; 0.001, 0.065]). Beyond a diastolic pressure of 70 mm Hg, a gradual increase in the intima-media thickness was observed. The association was most pronounced among subjects with relatively high pulse pressures.
Conclusions: Results of the present study indicate the existence of a J-shaped association between carotid atherosclerosis and diastolic pressure. These findings support the hypothesis that in elderly subjects, a low diastolic pressure may be a reflection of widespread atherosclerosis.