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Low Blood Pressure Risk Factor for 30-Day Mortality in Acute Ischemic Stroke

ARTICLE IN BRIEF

Ischemic stroke patients with systolic blood pressure lower than 140 mmHg were a significant 3.4 times more likely to die within 90 days, compared with patients with systolic BP between 140 and 179 mmHg.

SEATTLE—In patients with acute ischemic stroke, low systolic blood pressure is an independent risk factor for mortality at three months, Italian researchers reported here at the AAN annual meeting.

In a subgroup of patients with carotid stenosis or occlusion ipsilateral to the index stroke, “we found that systolic blood pressure of 180 mmHg or above was associated with a significantly lower risk of mortality at 90 days,” said lead investigator Maurizio Paciaroni, MD, staff neurologist in the Stroke Unit and Division of Cardiovascular Medicine at the University of Perugia.

Current guidelines do not call for lowering blood pressure during the acute phase of ischemic stroke, but no randomized trials have evaluated the issue, he said.

“There have been two studies suggesting you should lower blood pressure, but they were small, with limitations,” he added.

The new prospective study, which Dr. Paciaroni said is the first to evaluate the role of stenosis on the relationship between blood pressure and three-month mortality rates, involved 1,467 consecutive patients admitted within 12 hours of symptom-onset at four Italian hospitals.

STUDY PROTOCOLS

The mean age was 72.6 years, and 53.4 percent were men; 13.9 percent had had a previous stroke, and 75.4 percent had hypertension. The mean systolic and diastolic blood pressure levels were 153.7 mmHg and 84.5 mmHg, respectively, at admission.

Patients already taking drug therapy for hypertension and with systolic BP over 180 mmHg or diastolic BP over 110 mmHg were kept on the same treatment and included in the study. Patients requiring intensive treatment for hypertension in the first 48 hours were excluded.

Patients were followed up prospectively by medical visit or telephone. The primary endpoint was mortality at three-months. By three months, 13 patients were lost to follow-up and 133 had died (9.2 percent).

“Patients with low blood pressure had higher mortality at 90 days, with or without stenosis,” Dr. Paciaroni reported.

Even after adjusting for other risk factors, such as age, gender, cigarette smoking, hyperlipidemia, previous stroke and symptomatic ischemic heart disease, patients with systolic BP less than 140 mmHg were a significant 3.4 times more likely to die within 90 days, compared with patients with systolic BP between 140 and 179 mmHg.

Systolic blood pressure of 180 mmHg or higher was not associated with increased mortality, Dr. Paciaroni said. Additionally, no significant relationship was found between diastolic BP and mortality at three months.

“This is important because now we have to consider these patients differently in clinical trials,” Dr. Paciaroni said.

Systolic BP less than 140 mmHg was not associated with increased mortality, and no significant relationship was found between diastolic BP and mortality at three months.

Figure

DR. MAURIZIO PACIARONI: “We found that systolic blood pressure of 180 mmHg or above was associated with a significantly lower risk of mortality at 90 days.”

RANDOMIZED TRIALS NEEDED

Seemant Chaturvedi, MD, professor of neurology and director of the Stroke Program at Wayne State University in Detroit, said: “Blood flow to the brain is dependent on blood pressure, especially within the first 48 hours in the acute phase of stroke, So you don't want to lower blood pressure too much, as it will impede blood flow to the brain, leading to neurologic worsening.”

In people with more than 50 percent blockage of the carotid artery, “the new study provides indirect support for allowing blood pressure to be moderately elevated,” Dr. Chaturvedi said. However, a randomized study is needed before any firm conclusions can be drawn, he said.

Dr. Paciaroni said his group now hopes to obtain funding for a randomized controlled trial comparing 30-day outcomes among patients treated with antihypertension agents versus those given placebo, separating out those with stenosis from those who do not have a blocked vessel.