Blood Pressure and Acute Stroke
Up to 40% of acute stroke patients on hospital admission are already taking antihypertensive therapy, and up to 60% of patients will develop elevated blood pressure levels (SBP>160mmHg) as an acute complication of the stroke. Furthermore, nearly 20% of patients will become hypotensive (SBP <140mmHg). These changes in blood pressure are associated with adverse prognosis. However, the acute management of these post-stroke BP changes is a matter of some debate, as reflected in surveys of clinical practice, and recent national clinical guidelines indicate the need for further research to inform the management of this common clinical condition.
The Ageing and Stroke Medicine Research Group at Leicester University co-ordinated two United Kingdom multi-centre, prospective trials to address this question. The Continue Or Stop post-Stroke Antihypertensives Collaborative Study (COSSACS) (Principal Investigators: Professor T G Robinson, Professor JF Potter) was a randomized, open, blinded-endpoint study to assess whether existing antihypertensive therapy should be continued or discontinued within the first 24 hours for the first two weeks following acute ischaemic and haemorrhagic stroke onset.
The trial assessed blood pressure differences between continued and discontinued treatment groups for a variety of antihypertensive agents, and related differences to short- (2 weeks) and long-term (6 months) death and disability. The Controlling Hypertension and Hypotension Immediately Post-Stroke (CHHIPS) Trial (Principal Investigators: Professor JF Potter, Professor TG Robinson) was a randomized, double-blind, placebo-controlled, titrated dose trial to assess whether hypertension and hypotension should be therapeutically manipulated following acute stroke. The trial assessed the effects of acute pressor (0 to 12 hours) and depressor (0 to 24 hours) BP manipulation on early (<72 hours) neurological deterioration and 2-week death and dependency. The trial also assessed the influence of stroke subtype, time to treatment, and mode of treatment (including oral, sublingual and intravenous).
Impaired cardiac baroreceptor sensitivity is associated with poor long-term prognosis in survivors of acute myocardial infarction. Changes in cardiac baroreceptor sensitivity have also been reported in acute and chronic stroke patients, and preliminary findings suggest that impaired cardiac baroreceptor sensitivity and increased beat-to-beat blood pressure variability may be associated with increased long-term mortality in acute stroke survivors. Furthermore, central arterial stiffness is increased in stroke patients, and this is known to be a powerful long-term prognostic indicator of cardiovascular disease in the hypertensive population.
Cerebrovascular Autoregulation and Acute Stroke
To investigate further cerebrovascular auto-regulatory control mechanisms, particularly focal versus global mechanisms, to inform prognostic significance and future treatment strategies. This involves collaborative work with the medical physics group to investigate new non-invasive methods of cerebrovascular auto-regulation assessment including the use of MRI techniques.
I am UK Co-ordinating Investigator for two international hyperacute stroke trials (INTERACT 2, ENCHANTED).
I am on the TSC of the following trials: PIL-FAST (Chair); TOMAS and TARDIS.
I am the DSMS of the following trials: SOS, TRUST
I am involved in a number of recently completed and ongoing multi-centre stroke trials These include: Primary and Secondary Prevention Trials (SPORTIF, CHARISMA), Thrombolysis Trials (ECASS III, SITS-MOST), Neuroprotection Trials (SAINT 1, IMAGES).
The MRC Cognitive Function and Ageing Study was a United Kingdom, multi-centre study assessing disability over a long-term follow-up period in a random sample of community dwelling elderly. I have provided geriatric medical input to a group based in Leicester and Cambridge, which is involved in utilising these data to investigate important public health issues. These include the risk factors for disability onset in an ageing population, the burden of disability in an ageing population, and the potential for reducing future disability.