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 Strokes (accidents vasculaires)et hypertension,nouveaux éléments

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Date d'inscription : 15/05/2008

MessageSujet: Strokes (accidents vasculaires)et hypertension,nouveaux éléments   Ven 12 Mar - 20:41

Having high
blood pressure occasionally may pose a higher risk of having a stroke than having consistently high
readings: a series of UK-led
research papers published this week in leading journals suggests doctors
should not ignore one-off high blood pressure readings and consider
blood
pressure variability and maximum blood pressure as risk factors for
stroke rather than just average blood pressure.

You can read about the research in a series of papers published online
this week in The Lancet and The Lancet Neurology. The
lead
author is Dr Peter Rothwell, a professor of neurology at the University
of Oxford, UK.

Rothwell told the media that the main message coming out of the research
is that doctors have to start viewing blood pressure differently.

Current guidelines say that the priority is to lower blood pressure to
reduce the risk of having a stroke, but the work that Rothwell and
colleagues have
done suggests that doctors should also take into account blood pressure
variability and prescribe the drugs that result in the most steady blood

pressure.

In the study published in The Lancet, Rothwell and colleagues
looked at high blood pressure and visit-to-visit blood pressure
variability in
four groups of 2,000 people (UK-TIA trial and three validation cohorts),
each of whom had experienced transient ischemic attacks (TIAs), often
dubbed "mini-strokes", considered warning signs of stroke risk.

They found that in each TIA cohort, the visit-to-visit variability in
systolic blood pressure (SBP, the higher of the two blood pressure
readings that a
doctor takes, eg the 120 in a 120/80 reading) and maximum blood pressure
were both strong predictors of subsequent stroke.

Those participants with the greatest variation in SBP over seven GP
visits were six times more likely to have a major stroke and those with
the highest
blood pressure readings were 15 times more likely to have a stroke.

The authors concluded that:

"Visit-to-visit variability in SBP and maximum SBP are strong predictors
of stroke, independent of mean SBP."

In a second Lancet study, Rothwell and colleagues conducted a
meta-analysis (where you analysed data pooled from several studies of
similar design
and measurement criteria) of 389 controlled trials and found that blood
pressure
variability was a probable explanation for why some types of drugs were
more effective than others at preventing strokes.

In this second study, they concluded that:

"Drug-class effects on interindividual variation in blood pressure can
account for differences in effects of antihypertensive drugs on risk of
stroke
independently of effects on mean SBP."

And in a third study, published in The Lancet Neurology, Rothwell
and colleagues compared the effects of β blockers and calcium-channel
blockers on blood pressure variability and how this might impact risk of
stroke.


Previous studies have found that on the basis of mean blood pressure
alone, calcium-channel blockers reduce the risk of stroke more than
expected
and β blockers less than expected.

For this study they examined the results of two trials: the
Anglo-Scandinavian Cardiac Outcomes Trial Blood Pressure Lowering Arm
(ASCOT-
BPLA) trial involving 19,257 patients with hypertension and other
vascular risk factors, and a Medical Research Council (MRC) trial
involving 4,396
hypertensive patients.

They found that calcium-channel blockers and β blockers have opposite
effects on blood pressure variability: with the former gradually
reducing
variability over time, and the latter gradually increasing it.

The researchers concluded that the opposite effects of "calcium-channel
blockers and β blockers on variability of blood pressure account for the

disparity in observed effects on risk of stroke and expected effects
based on mean blood pressure"; they recommended that:

"To prevent stroke most effectively, blood-pressure-lowering drugs
should reduce mean blood pressure without increasing variability;
ideally they
should reduce both."


In a review article in The Lancet, Rothwell discusses what he
describes as the "shortcomings of the usual blood pressure hypothesis"
and
suggests avenues for future research.

He argues that while high blood pressure is the most common treatable
vascular risk factor, we don't know very much about how it causes
end-organ
damage and leads to vascular events, yet there is a widespread belief
that "underlying usual blood pressure can alone account for all
blood-pressure-
related risk of vascular events", and this has influenced guidelines for
diagnosis and treatment.

In the meantime, potentially valuable information is ignored, such as
variability in clinic blood pressure or maximum blood pressure reached,
with the
result that we know little about the effects of widely used drugs on
these measures, writes Rothwell.

Dr Philip B. Gorelick, a leading American expert on blood pressure and
stroke, and director of the Center for Stroke Research at the University
of
Illinois, who also wrote a commentary in one of the journals to
accompany the studies, told the media (as reported by HealthDayNews) the
findings
are "compelling" and may "revolutionize how we treat blood pressure in
the future":

"They provide a very important foundation for change in future
treatment," said Gorelick.

He said first doctors may begin to screen patients for blood pressure
variability and see if it is possible to select for classes of drugs
that reduce
it.

"And we can certainly adopt an at-home program to detect blood pressure
variability, although within-visit variability seems to be a more
important
factor," he added.

He said the study on the different effects on variability of
calcium-channel blockers and β blockers may also affect choice of the
first drugs
prescribed for blood pressure control:

"We would consider calcium channel blockers and diuretics for initial
use," said Gorelick.

Joe Korner, director of communications at The Stroke Association,
commented to the BBC about the new findings and said that people who
have
what is called episodic hypertension, where their blood pressure
occasionally registers a high reading, are often not treated.

Korner urged GPs to read the new research to help them decide the best
treatment for patients at risk of stroke.

In the UK, clinical guidelines are regulated by the National Institute
for Health and Clinical Excellence (NICE), and they are in the process
of
reviewing the guidelines on high blood pressure: it is understood that
they will be taking these latest studies into account.


"Prognostic significance of visit-to-visit variability, maximum
systolic blood pressure, and episodic hypertension."

Peter M Rothwell, Sally C Howard, Eamon Dolan, Eoin O'Brien, Joanna E
Dobson, Bjorn Dahlöf, Peter S Sever, Neil R Poulter.
The
Lancet
, Volume 375, Issue 9718, Pages 895 - 905, 13 March 2010
DOI:10.1016/S0140-6736(10)60308-X

"Effects of antihypertensive-drug class on interindividual
variation in blood pressure and risk of stroke: a systematic review and
meta-
analysis."

Alastair JS Webb, Urs Fischer, Ziyah Mehta, Peter M Rothwell
The
Lancet
, Volume 375, Issue 9718, Pages 906 - 915, 13 March 2010
DOI:10.1016/S0140-6736(10)60235-8

"Limitations of the usual blood-pressure hypothesis and importance
of variability, instability, and episodic hypertension."

Peter M Rothwell
The
Lancet
, Volume 375, Issue 9718, Pages 938 - 948, 13 March 2010
DOI:10.1016/S0140-6736(10)60309-1

"Effects of β blockers and calcium-channel blockers on
within-individual variability in blood pressure and risk of stroke."

Peter M Rothwell, Sally C Howard, Eamon Dolan, Eoin O'Brien, Joanna E
Dobson, Bjorn Dahlöf, Neil R Poulter, Peter S Sever, on behalf of the
ASCOT-BPLA and MRC Trial Investigators.
The
Lancet Neurology
, Early Online Publication, 12 March 2010
DOI:10.1016/S1474-4422(10)70066-1

Additional sources: HealthDayNews, BBC.


Written by: Catharine Paddock, PhD


Copyright: Medical News
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Nombre de messages : 369
Localisation : Groland
Date d'inscription : 01/09/2008

MessageSujet: Re: Strokes (accidents vasculaires)et hypertension,nouveaux éléments   Sam 13 Mar - 15:28

Merci ; je pige pas tout mais la notion de stabilité semble importante .
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Nombre de messages : 515
Date d'inscription : 15/05/2008

MessageSujet: Pression artérielle complémént (Cooper-DeHoff consultant )   Lun 15 Mar - 12:13

ACC: Pushing Blood
Pressure Too Low May be Harmful








By Todd Neale, Staff Writer, MedPage Today
Published: March 14, 2010


ATLANTA -- Lower is not necessarily
better for blood pressure control in patients with diabetes and coronary
artery disease, a secondary analysis of a randomized trial showed.
There was no difference in a composite endpoint of death, myocardial
infarction, or stroke between patients with an average systolic pressure
130-140 mm Hg and those with a lower average pressure, according to
Rhonda Cooper-DeHoff, PharmD, of the University of Florida in
Gainesville.
As expected, patients who had uncontrolled systolic blood pressure
(140 mm Hg and higher) had significantly increased cardiovascular risk,
she reported at the American College of Cardiology meeting here.
Patients who were most tightly controlled, however, had an increased
risk of all-cause mortality compared with those in the middle range,
during both the trial and an extended follow-up of about five years.
"We probably can rethink lower goals in this particular population
... and put our efforts toward lifestyle modifications and other things
where we can achieve benefit," Cooper-DeHoff said.
Past ACC president Douglas Weaver, MD, of the Henry Ford Health
System in Detroit, who moderated a press briefing at which the results
were discussed, found a mixed message in the results.
"So I guess the takeaway is that getting good blood pressure control
is good. Getting perfect blood pressure control may not be so good," he
declared.
Although guidelines recommend keeping systolic pressure below 130 mm
Hg in diabetic patients (with no lower boundary), evidence to support
that guidance is lacking, Cooper-DeHoff said.
To explore the issue, she and colleagues performed a pre-specified
secondary analysis of diabetic patients in the INVEST trial, which
compared two blood pressure-lowering strategies in 22,576 patients with
coronary artery disease and hypertension.
One approach led with the calcium channel blocker verapamil, followed
by the ACE inhibitor trandolapril and hydrochlorothiazide as needed.
The other led with the beta-blocker atenolol, followed by
hydrochlorothiazide and trandolapril as needed.
There were no differences between the strategies in blood pressure
control or on the primary endpoint of cardiovascular events.
In this secondary analysis, 6,400 patients with diabetes were grouped
in thirds, according to the mean on-treatment systolic blood pressure
control achieved during the trial:

  • Uncontrolled (140 mm Hg
    or higher)
  • Usual control (at least 130 mm Hg but less than 140
    mm Hg)
  • Tight control (less than 130 mm Hg).

As expected, the uncontrolled group had a significantly higher rate
of death, MI, or stroke (19.8%, P<0.0001).
But the tight and usual groups had a similar rate on the primary
outcome (12.7% and 12.6%, respectively), and on most of the secondary
outcomes.
However, during the trial, the tight control group had a slightly
higher rate of all-cause mortality than the usual control group (11%
versus 10.2%, P=0.035).
The elevated risk persisted in an extended follow-up lasting about
five years in the U.S. cohort of 5,077 patients.
After controlling for baseline characteristics, there was a 15%
higher risk of all-cause death in the tightly controlled group (HR 1.15,
95% CI 1.01 to 1.32, P=0.036).
To further evaluate mortality, the researchers broke the tightly
controlled group into two groups. In this group of patients with
systolic blood pressure below 130 mm Hg, mortality risk was increased
only when pressure dropped below 115 mm Hg.
Cooper-DeHoff acknowledged that the study was limited in that it was a
secondary analysis of a randomized trial, and thus, represented
observational data.
In addition, she said, the blood pressure levels during the extended
follow-up were unknown.
Finally, she said, the findings might not be generalizable outside
the specific population of diabetics with coronary artery disease.
Michael Crawford, MD, of the University of California San Francisco,
who served as a moderator of the session at which the results were
presented, also noted that patients in the uncontrolled group required a
greater number of medications than the other two groups -- and got
worse control as a result.
"This suggests that this is a unique group of patients with very
difficult-to-control blood pressure, and so these data may not be
applicable to someone who comes in on no drugs or on one drug and has a
blood pressure of 145," he said. "So this may not be broadly
applicable."


The trial and analysis were funded by Abbott
Laboratories.Cooper-DeHoff reported receiving a research grant
from the National Heart, Lung, and Blood Institute.Her co-authors
reported relationships with AstraZeneca, AtCor Medical, Daiichi Sankyo,
Eli Lilly, Pfizer, sanofi-aventis, Schering-Plough, Juvenile Diabetes
Research Foundation, GlaxoSmithKline, Forest Laboratories, CVRx, Merck,
Novartis, Boehringer-Ingelheim, Takeda, Abbott Laboratories, Walgreen's,
Bristol Myers-Squibb/Sanofi, Gilead, the National Heart, Lung, and
Blood Institute, Baxter, Bioheart Inc., Novartis/Cleveland Clinic,
NicOx
, Angioblast, NIH, Medtelligence, and SLACK Inc.Weaver
reported receiving consulting fees from Phrixis Pharmaceuticals,
receiving research grants from Johnson & Johnson, Schering-Plough,
and GlaxoSmithKline, and serving on data safety boards for trials
sponsored by Boston Scientific, The Medicines Co., Johnson &
Johnson, Bayer, Boehringer Ingelheim, and Direct Flow Medical.Crawford
reported no conflicts of interest.















Primary source: American College of Cardiology


Source reference:
Cooper-DeHoff R, et al "Rethinking lower BP goals for diabetics
with documented coronary artery disease -- findings fom the
International Verapamil SR -- Trandolapril Study (INVEST)" ACC 2010;
Abstract.
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MessageSujet: Re: Strokes (accidents vasculaires)et hypertension,nouveaux éléments   

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