In this study, Group 1 indicated the very high blood pressure group; the size of this group (n=83) was relatively small although the entire study group as a whole was large at n=515. The rates of patients with a history of high blood pressure, and kidney disease were significantly higher in Group 1, and they were more likely to have a history of being prescribed several kinds of antihypertensive drugs. They were also more likely to show atrial fibrillation and diabetes mellitus, although the difference was not significant. Their mRS scores on discharge and the length of stay were significantly higher, though NIHSS on admission was not significant between the two groups, which suggested that they were more likely to have a poorer prognosis. On logistic regression analysis with no previous history of hypertension, diabetes mellitus, arterial fibrillation, and kidney disease were independent risk factors associated with the presence of a high blood pressure. In patients without a history of hypertension, patients with diabetes, atrial fibrillation, and kidney disease were more likely to have elevated blood pressure early during stroke. Atrial fibrillation and kidney disease are common complications of late hypertensive disease and hypertension is more prevalent among patients with diabetes. These results suggest that multi-organ injury may be present in patients with high blood pressure, and thus acute phase high blood pressure is related to a poor prognosis. Generally, the blood pressure is elevated in the early stage of stroke, and it reaches a plateau within 24 hours, and then gradually starts to decrease in a week. In this study, only 28 (5.4%) and 10 (1.9%) acute inpatients spontaneously had a blood pressure of higher than 180/105 mmHg one week and two weeks after admission, respectively. The acute phase elevation in blood pressure is considered to play an important role in maintaining cerebral and collateral blood circulation in the penumbra region. However, the continuation of an elevated blood pressure has been suggested to lead to brain edema and reinfarction of ischemic lesions.14–16
Large epidemiological studies of acute ischemic stroke patients have demonstrated a U-shaped curve with respect to presenting blood pressure and outcomes.7
A low blood pressure group of patients would be put in with Group 2. Our study demonstrates that high blood pressure values were highly associated with early recurrent stroke and fatal brain edema.
Regarding the management of hypertension, the 2004 Japanese guidelines for the management of the stroke17
states that the careful administration of antihypertensive drugs is recommended only when extreme hypertension of ≥220 mmHg systolic and/or ≥130 mmHg diastolic continues or patients have aortic dissection, acute myocardial infarction, heart failure or kidney failure. However, the grade of recommendation is C1, which means that it is not based on adequate scientific evidence.
Some studies have reported that, in patients who were administered a high-dose bolus of nimodipine, a calcium antagonist, in the acute stage of stroke, a decrease in the diastolic pressure and deterioration of neurological scores were observed, which suggests the risk of rapid blood pressure reduction.18
However, the target blood pressure specifically related to the clinical entity, history and coexisting illnesses has not yet been proposed. The ACCESS study which was published recently reported that a 7-day course of candesartan, an angiotensin receptor II blocker (ARB), started within 36 hours rather than seven days after an acute ischemic stroke reduced the occurrence of cardiovascular events within a year after the stroke by 47.5%.11
These findings indicate the need to re-examine the conventional management of hypertension in the early stage of acute brain stroke. In the present study, it was suggested that patients with high blood pressure were more likely to have a history of hypertension, kidney disease and carotid stenosis. In these patients, a gradual decrease in the blood pressure on careful follow-up of the clinical symptoms may be favorable.
There are some limitations to this study. First, the number of patients was relatively small. Therefore, further evaluation with a larger number of patients is required. Second, the prognosis was measured by mRS scores on discharge; thus a follow-up period of three or six months is necessary. A large randomized comparison trial to investigate indications of antihypertensive drugs in the early stage of acute stroke is awaited.