There may be benefit from antihypertensive treatments, even at what we currently consider normal blood pressure levels
Dubbed “the silent killer”, sadly many individuals are unaware of their high blood pressure until affected by a significant complication for example heart attack or stroke. Naturally the consequences of such can be catastrophic, with significant physical disability as well as long lasting psychological unwell.
Presently, the management of raised blood pressure, or hypertension to use its medical terminology, has focussed on persons either with persistently elevated readings, or with borderline high numbers and other risk factors for cardiovascular disease, such as diabetes and kidney conditions.
However new research, looking at just under 350,000 individuals in 48 studies, has shown that irrespective of whether a person has risk factors for cardiovascular disease, there may be benefit from anti-hypertensive treatments, even at what we currently consider normal blood pressure levels.
The study, published in the Lancet, demonstrated that for every five mmHg (millimetre of mercury) reduction in systolic blood pressure (the top reading), cardiovascular complications, including heart attack, heart failure and stroke went down by between five and 13 per cent.
Blood pressure is recorded as two numbers in millimetres of mercury, although the majority of mercury machines will have been discarded due to safety concerns. The top number, or systolic, measures the pressure in your arteries as the heart contracts (systole). The bottom figure, or diastolic, represents the resting tone of the arterial system, when the heart is relaxed (diastole).
Both numbers are important. It is well established that diastolic hypertension, where the top number is within range, yet the bottom remains high, is a risk factor for cardiovascular disease, and that treatment reduces the risk of complications.
Current advice is to have your blood pressure checked at least once every five years after the age of 40. However high blood pressure may occur before this age. It is more common in those with diabetes, kidney disease and in some ethnic minorities, for example South Asian and Afro-Caribbean.
At the present time, hypertension is diagnosed if readings are persistently over 140/90 when tested in a medical facility, or if average home readings are greater than 135/85, it being assumed that you will be more relaxed in your own setting, hence the lower threshold. Another way of serially measuring blood pressure is ambulatory blood pressure monitoring (ABPM), where a cuff is attached to the arm and records a measurement every 30 minutes during the daytime and each hour at night. This is perhaps the most accurate way of compiling a true picture of an individual’s blood pressure. Hypertension cannot be diagnosed on a single reading, unless significantly elevated, and there can be significant variability due to factors such as time of day, exercise, caffeine, alcohol, tobacco, amount of sleep and emotional state.
Raised blood pressure is important because left untreated over time it puts strain on the heart which may cause heart failure. The increased pressure in blood vessels damages the lining either causing narrowing, or the vessel to actually tear. If this is a coronary artery a heart attack will occur, in the eye it may lead to blindness. In the brain a stroke will be the result. Literally any organ of the body can be affected.
Contrary to popular belief, hypertension is notoriously without symptoms. Most headaches and nose bleeds are not a sign of raised blood pressure. It may only cause you to feel unwell at extremely high levels, by which time the arteries will have been under considerable strain for a prolonged period.
It makes sense to know your numbers, if you are over 40, or under 40 and with risk factors for the development of raised blood pressure. I would certainly encourage anyone diagnosed with blood pressure to invest in a home machine, because a lot can happen between the current yearly checks.
So, does this mean that one day everyone will be on blood pressure medication? I would think not. Rather the study shows that damage to blood vessels may be occurring at blood pressures lower that those we currently assume are harmful. This is similar to the decision to reduce the recommended weekly alcohol consumption levels from 21 to 14 and indeed the current advice that even one unit a day can be harmful.
Hypertension is also a disease of ageing, with being over 65 a risk factor itself. A diagnosis should hopefully not distress, yet be an encouragement to be consistent in taking the prescribed medications, regularly check your numbers, and continue all the positive health practices that will hopefully help to keep these numbers within the recommended limits.