Stroke risk greatest in the morning

Nicanor woke up one morning to find lack of sensation in his left arm and leg. When he complained to his wife about the numbness, she suggested that Nicanor have his blood pressure checked. He, however, dismissed the idea that his feeling was caused by a high blood pressure. After all, it was early morning and he was well-rested during the night. Thinking that his wife is just overreacting, Nicanor went about his daily routine. When the feeling grew worse, however, his wife decided to take him to the hospital. It was found out that his BP rose to 170/100 mmHg.

Nicanor is just one of the many hypertensive patients who do not know that the surge in BP usually happens in the early morning during the first hours when one is awake. High BP can cause serious cardiovascular events such as heart attack, stroke and even death.

Although mornings are rarely associated with grim events such as heart attacks and stroke, a study shows that an excessive morning BP surge is a predictor of stroke especially among elderly people with hypertension.

The study, which was headed by Dr. Kazuomi Kario of the Department of Cardiology at Jichi Medical School in Tochigi Japan, observed 519 Japanese patients with high BP for an average of 41 months. All participants went through ambulatory BP monitoring and magnetic resonance imaging (MRI) scan to determine the presence of brain lesions which indicate a stroke.

Researchers calculated the morning blood pressure surge by measuring the average systolic blood pressure during the two hours after awakening, and subtracting the average systolic blood pressure during the one hour that included the lowest sleeping blood pressure.

Participants were then divided into morning surge (MS) group consisting of patients with morning BP increase of 55 mmHg or greater and the non-MS group consisting of patients with morning BP increase of less than 55 mmHg.

Results based on the MRIs showed that participants in the MS group were 57 percent more likely to have multiple "silent" strokes than the non-MS patients.

In addition, 19 percent of those in the MS group had a stroke during the follow-up period compared with 7.3 percent of people from the non-MS group.

The study also showed that relative risk of stroke for people with a morning surge was nearly three times higher than for people without the surge.

Researchers also found that a 10 mm Hg increase in the morning blood pressure surge increased stroke risk by 22 percent.

The findings of the study provide new insights in the way clinicians treat hypertension. Kario suggested that the morning surge in BP could be a new target for drug treatment to prevent subsequent stroke in patients with high BP.

Clearly, it is important to choose a drug that provides sustained 24-hour BP control even in the early morning hours. Telmisartan, an angiotensin II receptor blocker (ARB), has been shown to provide consistent 24-hour BP control even in the risky early morning hours.

In a study by Lacourciere et al published in the journal Blood Pressure Monitoring comparing telmisartan and amlodipine, it was shown that telmisartan provided a better diastolic BP control than amlodipine, throughout the 24-hour period.

For patients with less than optimum BP control with monotherapy, a fixed-dose combination containing telmisartan and hydrochlothiazide is available to bring better BP control throughout the 24-hour period, including the early morning hours.

Investigators from the Center Hospitalier Universitaire de Québec in Québec compared the effect of the combination of the angiotensin II antagonist telmisartan (40 mg) plus the diuretic hydrochlorothiazide (12.5 mg) with telmisartan alone in 327 patients with mild to moderate hypertension who had failed to respond adequately to telmisartan monotherapy.

After eight weeks, 51.6 percent of the patients receiving the combination therapy had normalized blood pressure compared with 23.5 percent in the monotherapy group. A decrease in systolic BP of at least 10 mmHg was achieved in 63.5 percent of the combination therapy patients compared with 42.6 percent of the monotherapy patients.

Diastolic BP was normalized in 64.8 percent of the combination therapy patients compared with 40.1 percent of the monotherapy patients.

Currently being conducted worldwide is the study called the Ongoing Telmisartan Alone and in Combination with Ramipril Global Endpoint Trial (ONTARGET). It is one of the largest clinical study programs which investigate the role of ARB telmisartan and ACE inhibitor ramipril in the prevention of heart attack, cardiovascular death and stroke.

The study will be finished in 2007 and is expected to provide the answers on how telmisartan can help patients like Nicanor. The main sponsor of ONTARGET is Boehringer Ingelheim.