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Losartan Preserves Cerebral Blood Flow in Hypertensive Patients With a History of Stroke

Losartan appears to preserve cerebral blood flow (CBF) in hypertensive patients with a history of stroke, new research suggests.

In patients with severe hypertension, chronic heart failure or a history of stroke, the lower limit of CBF autoregulation is shifted to higher levels of blood pressure (BP) than in healthy subjects. Thus, the goal of pharmacotherapy in hypertensive patients with an impaired autoregulation of CBF is to reduce BP while preserving an appropriate CBF.

Hiroshi Moriwaki, MD, with the Department of Cerebrovascular Medicine, National Cardiovascular Center, Suita, Osaka, Japan, and colleagues investigated 16 hypertensive patients who had experienced a stroke at least 4 weeks before study entry.

Patients received losartan, an angiotensin II receptor antagonist, 25-100 mg, once daily, for 4 weeks. Ambulatory systolic blood pressure (SBP) and diastolic blood pressure (DBP) were recorded for 24 hours. Single photon emission tomography with N-isopropyl-p-[(123)I]iodoamphetamine was used to quantify CBF in the cerebrum and cerebellum.

Before treatment, CBF was 29.7 ± 6.7 mL/min/100 g in the cerebrum and 31.5 ± 7.5 mL/min/100 g in the cerebellum. After treatment, BP was lower; the effective average reduction was 13.7 mm Hg in 24-h SBP and of 8.1 mm Hg in 24-h DBP. However, CBF increased by 7.7% in the cerebrum, and remained at the baseline level in the cerebellum, indicating that CBF was preserved despite the reduction in BP.

"Administration of losartan to hypertensive patients with a history of stroke for four consecutive weeks resulted in a decrease of BP with a preserved blood flow in both the cerebrum and cerebellum," Dr. Moriwaki and colleagues conclude. "The blockade of angiotensin II AT1 receptors by losartan is considered to be safe in such patients, because it preserves the function of autoregulation of cerebral blood flow in therapy of BP control," they add.

"The beneficial effect of losartan in hypertensive patients with a history of stroke may be explained by its acute effect that is similar to that of ACE inhibitors, as well as by its chronic effect on vascular tissue, through which it ameliorates its structure and function," they suggest.

J Hum Hypertens 2004 May 6 [Epub ahead of print] "Losartan, an angiotensin II (AT(1)) receptor antagonist, preserves cerebral blood flow in hypertensive patients with a history of stroke"

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