New directions in blood pressure control

More than 7,000 hypertension experts from all over the world convened recently in Prague, Czechoslovakia to discuss new directions in preventing complications of high blood pressure (BP), primarily stroke and heart attack. It was the joint meeting of the International Society of Hypertension (ISH) and European Society of Hypertension.

Many experts now label hypertension as a "non-infectious epidemic" with an increasing prevalence of 20 to 25 percent among the adult population. The sad part, however, is that less than half of the hypertensives are aware that they have high blood pressure, and less than one-fourth are adequately treated even in advanced countries.

The statistics in developing and underdeveloped countries are even more appalling which should raise the alarm for local health experts. Increased BP levels have been implicated as directly responsible for the majority of stroke deaths and a substantial proportion of deaths from coronary heart disease (CHD).

Thus, BP control has been repeatedly emphasized to have indisputable importance in reducing the risk of stroke, whether the cause is due to a blood clot in the artery (ischemic stroke) or rupture of the artery (hemorrhagic stroke).

‘Blood thinners’

Most experts agree that the so-called "blood thinners" or anti-platelet drugs can only reduce the risk of a recurrent ischemic stroke by 20 to 25 percent and even complete blockade of platelet function does not improve long-term outcome of the patient.

Despite all the advances over the last 20 years, medical experts are humbled by the still glaring limitations of current therapies to adequately control BP and prevent its complications.

There are some important facts, however, which guide most scientists in coming up with newer strategies to lick hypertension. The long-term prognosis or outlook of hypertensives is determined by the level of BP reached during therapy; the presence of existing damage to vital organs such as the heart, brain and kidneys; and the presence of other risk factors such as diabetes, high blood cholesterol, insulin resistance and obesity. Hence, experts have now coined the term "global" risk assessment and treatment to emphasize that hypertensives should be managed thoroughly with all the risk factors covered and not on a piece-meal basis with a simple control of the elevated BP.

Randomized clinical trials

The finding that elevated BP predisposes to stroke prompted a series of well-designed trials called randomized clinical trials (RCTs) to determine whether antihypertensive therapy can prevent primary strokes or not. An incisive analysis of 17 such RCTs involving approximately 50,000 patients treated with various antihypertensives for five years, showed that by reducing the diastolic BP modestly by just five to six mmHg, or the systolic BP by 10 to 12 mmHg, the probability of a first stroke can be reduced by 35 to 40 percent. It therefore suggests that if physicians could just be more aggressive in bringing down the BP to desired or optimal levels, this noted benefit would even be more significant.

Recent highly recognized RCTs, which come in easy-to-remember acronyms, have consistently shown the efficacy of the newer antihypertensives in lowering the incidence of strokes, heart attacks and other cardiovascular complications, including deaths.

Examples of these RCTs are the Losartan Intervention For Endpoint reduction (LIFE) trial, the Study on COgnition and Prognosis in the Elderly (SCOPE), Heart Outcomes Prevention Evaluation (HOPE) and the Perindoprill pROtection aGainst REcurrent Stroke Study (PROGRESS).

‘Mother of all trials’

A currently ongoing trial, which is described to be the "mother of all landmark trials," is the ONgoing Telmisartan Alone and in combination with Ramipril Global Endpoint Trial (ONTARGET). It is expected to unravel the interrelationships among hypertension, stroke, atrial fibrillation (irregular heartbeat) and brain or mental cognitive impairment. This highly ambitious project involves almost 30,000 patients at 793 sites in 40 countries over more than five years of treatment.

A parallel trial to the ONTARGET study is the Telmisartan Randomized AssessmeNt Study in ACE inhibitor-iNtolerant subjects with cardiovascular Disease (TRANSCEND) trial. It will determine if an angiotensin receptor blocker, which is considered the "new kid on the block" in antihypertensive therapy, can confer the same benefits to patients who have intolerable side-effects to the older antihypertensive drug called ACE inhibitors. Newer drugs are now being evaluated not only on the basis of effectiveness, but also in terms of tolerability and safety.

Patient compliance has also been implicated as a major factor which can improve BP control. In the United States and Europe, where medicine cost is covered by either the government or the patients’ health insurance, this is still regarded as a serious problem.

Lifestyle changes

It is easy to imagine how much worse it can be in countries such as the Philippines where the average worker may have to choose between buying food and medicines. Thus, many patients resort to just taking their antihypertensive pills when they have symptoms which experts repeatedly warn is a risky practice since only a small percentage of hypertensive patients may present with symptoms even with dangerously high BP levels.

Because of the increasing cost-burden of antihypertensive therapy, most experts recommend that therapeutic lifestyle changes (TLC) have to be repeatedly emphasized in antihypertensive therapy. These changes cover diet, exercise, smoking cessation, weight and stress management.

Recent guidelines on hypertension management stress its importance for all types and levels of hypertension. By itself, it may be sufficient to control low-risk and mild hypertension. Even in moderate to high-risk patients, it can help reduce the dosage and number of antihypertensive drugs the patient needs to take.

The big challenge to most physicians and patients though is to implement TLC strictly and consistently. Most agree that it is easier said than done, but it is also easier done if physicians can set the example for their patients – which may not be the easiest thing for a physician to do.

(CHARTER is the acronym for Clinical Hypertension and Atherosclerosis Research on Therapies, Epidemiology and Risk-management. The bureau is a non-stock, non-profit research foundation which advocates healthy lifestyle changes in the prevention of many common medical problems. It is based at the Manila Adventist Medical Center. The author is a member of its board of trustees. For feedback, e-mail at [email protected].)