BP effects on vasculature begin below hypertensive threshold

By Eleanor McDermid

Higher systolic blood pressure (SBP) is associated with increased carotid intima-media thickness (cIMT) even within the normotensive range, research shows.

Patrick Rossignol (Université de Lorraine, Nancy, France) and study co-authors found a linear association between ambulatory SBP and cIMT in 696 adult participants of the population-based STANISLAS cohort. This was true for the 217 participants with a history of hypertension and for the 479 without.

The risk of having cIMT greater than 900 μm was less than 5% in both groups at a 24-hour SBP below 110 mmHg. But at SBP above 130 mmHg, it rose to more than 20% in people with a history of hypertension and to about 10% in people without.

The fact that the correlation was linear, rather than nonlinear, "can explain, to some extent, the association of 'prehypertension' with poorer outcome", the team writes in the Journal of the American Heart Association.

After accounting for variables including age, gender, smoking and antihypertensive treatment, each 5 mmHg increase in 24-hour SBP was associated with a significant 7.3 µm increase in cIMT. Diastolic BP was not associated with cIMT.

The researchers say their findings also imply that the outcomes of treated hypertensive patients will varying according to their achieved SBP, with "a detrimental effect of BP at the higher end of the normal range".

This is in agreement with the findings of the SPRINT trial, in which patients treated to an office SBP target of less than 120 mmHg had fewer adverse cardiovascular events than those treated to a target of less than 140 mmHg.

"The better clinical outcome associated with intensive treatment might be partially linked to a lesser degree of vascular damage in patients with more strict BP control", say Rossignol et al.

They note that, among treated hypertensive STANISLAS participants, the risk of cIMT greater than 900 µm was reduced twofold in those with 24-hour SBP mmHg below 110 mmHg, compared with those whose SBP was around 130 mmHg.

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