Inpharma 1230 - 25 Mar 2000

Antihypertensive therapy in stroke: Are guidelines being ignored?The American Heart Association (AHA) and otherhow low should you go?

organisations have developed guidelines that baseAntihypertensive therapy is commonly employed in antihypertensive therapy on the extent to which BP rises

the management of patients with acute stroke, both in a patient with stroke, said Professor Lawrence Brassischaemic and haemorrhagic. However, some evidence from Yale University, New Haven, US.has suggested that overly aggressive lowering of BP Concern about BP in patients with stroke can lead tomight cause more harm than good in some patients with unnecessary treatment, according to the results of anstroke. Additionally, a US study evaluating clinical ongoing study of current medical practices at 36management standards has found that many patients academic medical centres in the US. Characterised as awith stroke receive unnecessary antihypertensive ‘benchmarking project’, the study has shown that overtherapy. Two new studies have provided evidence to half of patients with stroke receive antihypertensivesuggest that aggressive BP management is a feasible and therapy, and the figure reaches 100% at someuseful clinical goal in acute stroke. One of these studies institutions, as reported 2 years ago at the AHA-showed a lower rate of stroke recurrence in association sponsored stroke conference.with lower diastolic BP, and the other demonstrated ‘We know that treating blood pressure is one of theimproved cerebral blood flow with aggressive BP most effective ways to prevent stroke’, said Professormanagement in acute haemorrhagic stroke, though not Brass. ‘However, that is not the case in the setting ofin all patients. The findings were reported at the acute stroke. In a stroke, blood supply has been cut off toAmerican Stroke Association 25th International Stroke part of the brain. Blood pressure normally goes up, andConference [New Orleans, US; February 2000]. that’s a good response for the short term. You don’t want

Contradicting findings from a previous Japanese to lower blood pressure too much during a stroke’.study, US investigators reported better outcomes in The benchmarking data also showed that physicianspatients with stroke who had low, compared with high, frequently ignored guidelines when initiatingdiastolic BP. antihypertensive therapy. To encourage better stroke

Impetus for the investigation came from the lack of care, hospitals should develop check lists, much likedata on optimal management of BP following acute those that airline pilots use before every takeoff,stroke, said Dr Gary Friday from Lankenau Hospital, Professor Brass suggested.Wynnewood, US. Moreover, findings from a case series ‘A pilot doesn’t climb into a plane and say "It’s filledof 368 hypertensive Japanese patients with stroke had with gas and everything looks good, so let’s take off andsuggested a J-shaped relationship between BP reduction see what happens"’, he observed. ‘Unfortunately, that’sand recurrent stroke.1 the way we practice medicine in many cases. Medical

practice has become sufficiently complex that we needConflicting conclusionsreminders to take care of the mundane issues’.In the Japanese study, patients whose diastolic BP fell

below 80mm Hg had an increased risk of stroke Getting aggressive with BPrecurrence compared with patients whose diastolic BP A small imaging study reported at the stroke meetingremained between 80 and 84mm Hg. The study further provided evidence that aggressive BP management maysuggested a narrow window of BP protection, as benefit hypertensive patients with acute haemorrhagicpatients with a diastolic BP of 85mm Hg or higher also stroke. Investigators employed serial xenon computedhad an increased risk of stroke recurrence. tomography imaging to measure focal and regional

Dr Friday and colleagues evaluated the relationship blood flow in response to antihypertensive therapy in 7between BP and stroke recurrence in 662 patients patients who had documented acute cerebralenrolled in the Lehigh Valley Recurrent Stroke Study. haemorrhages.Chart reviews showed that 535 patients survived The antihypertensive protocol called for reducingwithout recurrent stroke to an initial 4-month follow-up systolic BP to a range of 160–170mm Hg andevaluation. Patients had subsequent follow-up visits at subsequently to a goal of 130–140mm Hg. Systolic BP6-month intervals, continuing up to 4 years in some averaged 220mm Hg on presentation in the 7 patients,instances. The investigators analysed both lowest and according to Dr James Gebel from the University ofaverage follow-up diastolic BP as predictors of stroke Pittsburgh, US.recurrence. Medications used in the study included labetalol and

The investigators determined that 500 patients had a hydralazine. If antihypertensive drip therapy waslowest diastolic BP of < 80mm Hg at one or more time required, sodium nitroprusside or esmolol was used.points. Compared with patients whose lowest follow-up Mean systolic BP was 164mm Hg after the first phase ofdiastolic BP was 80–89mm Hg, those with lower BP reduction and 138mm Hg after the second phase.measurements had a relative risk for stroke recurrence A xenon scan was performed after each treatmentof 0.4 (p = 0.02). However, when the analysis phase. For each scan, the investigators calculatedcompared patients according to average diastolic BP, quantitative cerebral blood flow values for both globalthose with a BP of < 80mm Hg maintained an and regional flow, as well as for intrahaematomal andassociation with reduced risk of stroke recurrence, perihaematomal flow.compared with those having a higher BP, but the Overall, the scans showed increased global anddifference was no longer statistically significant. regional cortical cerebral blood flow in response to BP

‘Long-term diastolic blood pressure below 80 lowering. However, analysis of perihaematomal andfollowing stroke is not associated with an increased risk intrahaematomal blood flow revealed significantlyof recurrent stroke’, stated Dr Friday. ‘In fact, a diastolic decreased flow in 2/7 patients.blood pressure of less than 80 might be associated with a ‘Most patients appear to tolerate this regimen ofdecreased risk of recurrent stroke compared to a diastolic aggressive blood pressure reduction and have eitherblood pressure of 80–89’.

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stable or increased general and regional cortical cerebralblood flow’, said Dr Gebel. ‘However, some patientsapparently did not tolerate the regimen so well, asindicated by the decreased intrahematomal andperihematomal blood flow we documented in 2patients. We believe that use of this type of quantitativeinformation might allow safer and more discriminate useof aggressive blood pressure reduction and potentiallyother medical and surgical therapies in patients withacute hypertensive intracerebral hemorrhage’, heconcluded.1. Irie K, et al. The J-curve phenomenon in stroke recurrence. Stroke 24:

1844-1849, Dec 1993.800763412

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