A new review has found that lowering blood pressure below the "standard" target
of 140/90 mm Hg is not beneficial in terms of reducing mortality or morbidity
[1]. Dr Jose Agustin Arguedas (Universidad de Costa Rica, San Pedro de Montes de
Oca) and colleagues report their findings online July 8, 2009 in the Cochrane
Database of Systematic Reviews.

They explain that over the past five years, a trend toward lower targets has
been recommended by hypertension experts who set treatment guidelines, "based on
the assumption that the use of drugs to bring the BP lower than 140/90 mm Hg
will reduce heart attack and stroke." But this approach "is not proven," they
point out.

Arguedas told heartwire that they reviewed seven trials with more than 22 000
subjects comparing lower or standard diastolic BP targets, but they were unable
to identify any studies comparing different systolic BP targets. "We found there
is no evidence that reaching a target of below 90 mm Hg diastolic BP will
provide additional clinical benefit, but we can't say whether lowering systolic
BP below 140 mm Hg will be beneficial or not; there are no data."

Dr Franz Messerli (St Luke Roosevelt Hospital, New York, NY), who was not
involved with this review, told heartwire that there is no question that the
140/90-mm-Hg BP limit is "absolutely arbitrary, and the benefits of
antihypertensive medications are most obvious in patients with the highest BP.
The closer we get to 'normotension,' the more difficult it becomes to show
benefits of BP lowering.

"The Lewington meta-analysis of one million patients has convincingly shown that
people fare better¡Xie, have fewer strokes and heart attacks¡Xwhen their 'usual'
BP is 115/70 mm Hg compared with those with a 'usual' BP of 130/80," Messerli
adds. "However there are no data and probably never will be that lowering BP
from 130/80 mm Hg to 115/70 mm Hg confers any benefits," he says.

Further Review Required in at-Risk Patients

Attempting to achieve lower BP targets has several consequences, the researchers
note; "the most obvious is the need for large doses and increased number of
antihypertensive drugs. This has inconvenience and economic costs to patients.
More drugs and higher doses will also increase adverse drug effects, which if
serious could negate any potential benefit associated with lower BP." There is
also the potential that lowering BP too much may cause adverse cardiovascular
events, the so-called "J-curve" phenomenon, they observe.

In their review, they included: the Modification of Diet in Renal Disease (MDRD)
trial; the Hypertension Optimal Treatment (HOT) study; the BP Control in
Diabetes (ABCD) trials H and N; the African American Study of Kidney Disease and
Hypertension (AASK), and the Renoprotection in Patients With Nondiabetic Chronic
Renal Disease (REIN-2) study.

They found that, despite a 4/3-mm-Hg-greater achieved reduction in
systolic/diastolic BP (p<0.001), attempting to achieve "lower targets" instead
of "standard targets" did not change:

Total mortality (relative risk 0.92).
MI (RR 0.90).
Stroke (RR 0.99).
Congestive heart failure (RR 0.88).
Major cardiovascular events (RR 0.94).
End-stage renal disease (RR 1.01).
"This strategy did not prolong survival or reduce stroke, heart attack, heart
failure, or kidney failure," they note. "More trials are needed, but at present
there is no evidence to support aiming for a blood-pressure target lower than
140/90 mm Hg in any hypertensive patient."

The researchers say they were unable to fully assess the net health effect of
lower targets due to lack of information regarding all total serious adverse
events and withdrawals due to adverse effects in six of seven trials.

Trials Needed to Compare Lower With Standard Systolic Targets

Arguedas and his colleagues note that a lower BP target of 130/80 mm Hg is
currently recommended for at-risk patients, and they did perform a sensitivity
analysis in diabetic and kidney-disease patients, which did not show significant
benefits for treating to targets of lower than 135/85 mm Hg. "However, in these
two populations, the evidence for a lack of benefit is less robust," they note.

Arguedas told heartwire that properly conducted randomized controlled trials are
needed comparing lower systolic BP targets with standard ones in the general
population and also in specific subgroups of at-risk patients.

One such study is the ongoing Action to Control Cardiovascular Disease in
Diabetes (ACCORD) blood-pressure trial¡Xan unmasked, open-label, randomized
trial with participants randomized to one of two groups with different treatment
goals: systolic blood pressure <120 mm Hg for the more intensive goal, and
systolic blood pressure <140 mm Hg for the less intensive goal [2].

The primary outcome measure is the first occurrence of a major CVD event,
specifically nonfatal MI or stroke, or cardiovascular death during a follow-up
period ranging from four to eight years. The results should provide some of the
first definitive clinical-trial data on the possible benefit of treating to a
more aggressive systolic blood-pressure goal.

In the meantime, says Arguedas, "We are doing another separate systematic review
specifically in patients with diabetes and chronic kidney disease to see whether
targets lower than 130/80 mm Hg change morbidity or mortality as compared with
standard targets."