Blood Pressure and Clinical Outcome in Acute Ischemic Stroke
To the Editor:
We read with interest the recent report about the relationship between blood-pressure and clinical outcome in acute ischemic stroke.1 On the basis of an analysis of a single blood pressure value before randomization in the IST trial, the authors found that high and low initial blood pressure values were associated with a worse clinical outcome. However, many of the patients, particularly those with high blood pressure values, were probably treated with antihypertensive agents in the acute phase. A relationship between a blood pressure drop within the first 24 hours after acute stroke and worse outcome in patients with acute ischemic stroke has recently been reported.2 For a clinically relevant interpretation of the data from the IST trial, it is therefore crucial to differentiate whether high blood pressure levels themselves or, vice versa, the subsequent treatment with antihypertensive drugs in many of these patients, might have negatively influenced the outcome. The clinical consequences of these 2 hypotheses are completely opposite. We are concerned that many physicians will interpret the IST data as evidence to lower blood pressure levels in the acute phase if the systolic BP exceeds 150 mm Hg, which may be detrimental for their patients (in fact, we do not know). Such a misinterpretation is further promoted by the formulation of the authors that “patients with higher pressures might have a better outcome… if their blood pressure was actively lowered with an appropriate drug.” However, the authors should have clearly noted that the opposite might also be true in order to avoid premature clinical decisions on the basis of observational evidence. As the authors correctly state, randomized evidence is required.
- ↵Leonardi-Bee J, Bath PMW, Phillips SJ, Sandercock PAG, for the IST Collaborative Group. Blood pressure and clinical outcomes in the International Stroke Trial. Stroke. 2002; 33: 1315–1320.
- ↵Castillo J, Davalos A, Leira R, Serena J, Pato A, Castellanos M. Influence of blood pressure in the acute phase of ischaemic stroke on brain injury and stroke outcome. Cerebrovasc Dis. 2001; 11: 7.Abstract.
Lalouschek and Lang question the cause of our finding1 relating blood pressure in acute ischemic stroke and subsequent outcome; specifically, they raise the possibility that active treatment for the high blood pressure might have caused a poor outcome, rather than the high blood pressure itself. We acknowledge that some drugs that lower blood pressure can be detrimental, as shown in some randomized controlled trials of β-receptor antagonists and calcium channel blockers,2,3⇓ although this may not be true for all classes of antihypertensive agents. For example, candesartan appeared to improve outcome in one trial.4
The International Stroke Trial5 did not record the use of drugs that lower blood pressure, so we cannot altogether discount the above suggestion. Nevertheless, it is unlikely that there was any significant or systematic use of drugs to lower blood pressure because most stroke physicians have noted the results of trials such as INWEST and BEST2,3⇓ and are concerned that reducing blood pressure might reduce cerebral perfusion in the presence of damaged autoregulation. This assertion is supported by a published survey in which few physicians reported that they routinely lower high blood pressure.6
Our article did not aim to suggest that stroke physicians should actively lower high blood pressure but rather to provide further observational evidence supporting the need for one or more large trials7 to investigate this question further and define future management.
- ↵Leonardi-Bee J, Bath PMW, Phillips SJ, Sandercock PAG, For the IST Collaborative Group. Blood pressure and clinical outcomes in the International Stroke Trial. Stroke. 2002; 33: 1315–1320.
- ↵Barer DH, Cruickshank JM, Ebrahim SB, Mitchell JR. Low dose beta blockade in acute stroke (“BEST” trial): an evaluation. BMJ. 1988; 296: 737–741.
- ↵Schrader J, Luders S, Kulschewski A, et al. ACCESS Study: Acute Candesartan Cilexetil Evaluation in Stroke Survivors: double-blind randomised comparison of candesartan cilexetil and placebo in the control of blood pressure following stroke. German Hypertension Society. 2001.
- ↵Bath PMW, Weaver C, Iddenden R, Bath FJ. A trial of blood pressure reduction in acute stroke. Age Ageing. 2000; 29: 554–555.
- ↵Bath PM. Major Ongoing Stroke Trials. Efficacy of Nitric Oxide in Stroke (ENOS) trial. Stroke. 2001; 32: 2450–2451. Abstract.