High blood pressure and cardiovascular risk: the silent killer

High blood pressure is one of the most powerful cardiovascular risk factors — and, paradoxically, one of the least well controlled worldwide, despite effective treatments that have been widely available for decades.

A major risk factor for several organs at once

Persistently high blood pressure gradually weakens several organs at the same time:

• The heart, which has to work harder to pump blood, with an increased risk of heart failure over the long term, as the heart muscle gradually thickens to compensate for this extra effort
• The brain's arteries, with an increased risk of stroke — hypertension is the leading modifiable risk factor for stroke, ahead of even smoking or diabetes
• The coronary arteries, with an increased risk of heart attack, as hypertension promotes the development of atherosclerotic plaques on the walls of these arteries
• The kidneys, whose filtering function can gradually decline under the effect of prolonged excess pressure, potentially creating a vicious cycle since impaired kidney function can itself worsen hypertension
• The eyes, with a risk of damage to the blood vessels of the retina (hypertensive retinopathy), less well known but well documented

Insufficient control, everywhere in the world

What makes the situation particularly concerning isn't just how common hypertension is, but the small proportion of people whose blood pressure is actually well controlled. According to the World Health Organization, only about 23% of adults with hypertension worldwide have their blood pressure under control. In the United States, that figure reaches about 21%; in France, about one in four people with hypertension still receives no treatment at all. These figures, consistent despite very different health systems, show that this isn't a problem isolated to one country, but a public health challenge shared internationally.

Why this poor control is particularly unfortunate

Hypertension is one of the few cardiovascular risk factors for which effective, well-tolerated, inexpensive medications have existed for decades. The gap between the proven effectiveness of these treatments and their low actual use worldwide points to a problem that is less scientific than organizational: access to care, insufficient screening, or simply not knowing one's own status, with no symptom to raise the alarm, as mentioned in the first article on this blog.

What treatment helps prevent

The benefits of well-controlled blood pressure are among the best proven in all of medicine. A review of 123 trials covering more than 600,000 people, published in 2016 in The Lancet (Ettehad et al.), showed that a 10 mmHg reduction in systolic pressure lowered the risk of a major cardiovascular event by about 20%, stroke risk by 27%, heart failure risk by 28%, and all-cause mortality by 13%. This benefit is seen regardless of the starting level, including in older people.

The American SPRINT trial, published in 2015 in the New England Journal of Medicine, went further. In more than 9,000 adults at high cardiovascular risk, aiming for a systolic pressure under 120 mmHg, rather than 140 mmHg, reduced cardiovascular events by about a quarter. This result fueled debate over treatment targets, at the cost of somewhat more side effects, such as excessive drops in blood pressure.

In practice, these figures mean that treated hypertension is no longer the same risk factor. The real challenge is consistency: taking treatment every day, for years, for a condition that isn't felt. Talking to your doctor or pharmacist about a missed dose or a bothersome side effect almost always helps find a solution.

A factor that combines dangerously with others

As with smoking or diabetes, hypertension shouldn't be considered in isolation: combined with other cardiovascular risk factors (smoking, high cholesterol, diabetes), it multiplies overall risk rather than simply adding to it, following the same multiplicative logic detailed on the blog dedicated to overall cardiovascular risk. This is why systolic blood pressure is one of the variables directly included in the overall cardiovascular risk calculation (SCORE2), alongside smoking and cholesterol.

The DASH diet, a particularly well-documented approach

Among recommended lifestyle measures, the DASH diet (Dietary Approaches to Stop Hypertension) holds a special place — it's one of the most scientifically well-documented dietary approaches for managing blood pressure, explicitly cited in French guidelines from the French Society of Hypertension, alongside the Mediterranean diet.

This diet favors fruits and vegetables, whole grains, low-fat dairy products, legumes, and nuts, while strongly limiting salt (the recommended target in France is no more than 5 g of salt a day, or about 2 g of sodium), saturated fat, and added sugars. Clinical trials evaluating this diet have shown a reduction in systolic blood pressure of several points in people with hypertension, an effect comparable to that of certain low-dose medications — a notable result for a purely dietary intervention, with no associated side effects.

The value of the DASH diet isn't limited to reducing salt alone: increasing potassium intake (through fruits and vegetables) also plays a documented role in lowering blood pressure, through a mechanism that promotes sodium elimination by the kidneys. It's this combination of several nutritional levers at once, rather than a single isolated restriction, that explains this approach's effectiveness in clinical studies.

Management that often starts with lifestyle

Before considering medication, reducing salt intake, regular physical activity, limiting alcohol consumption, and managing weight are first-line levers, capable on their own of significantly lowering blood pressure in many people, particularly with mild to moderate hypertension. These measures also remain recommended alongside medication when it is needed, since the two approaches are never mutually exclusive.

A risk that begins before the hypertension threshold itself

A point emphasized by the most recent guidelines: cardiovascular risk linked to blood pressure doesn't follow a strict threshold logic, below which there would be no risk at all, and above which danger would suddenly appear. Current data show a progressive relationship, with cardiovascular mortality already rising slightly from blood pressure levels previously considered completely normal (around 115/75 mmHg). This is an additional argument against feeling overly reassured by a result “just below” the hypertension threshold, without giving in to worry either: this finding mainly justifies vigilance and follow-up over time, rather than systematic treatment at these lower levels.

Situations that call for immediate help

High blood pressure found during a single isolated measurement isn't an emergency if it comes with no symptom: recheck it at rest and talk to your doctor about it. However, call 15 (or 112) in France right away when very high blood pressure, 180/110 mmHg or more, comes with chest pain, shortness of breath, a sudden and unusual severe headache, vision problems, paralysis, or trouble speaking. In the United States, call 911. These signs can indicate an ongoing complication, such as a heart attack or stroke.

What to remember

Unlike other chronic diseases that are harder to treat, well-monitored, well-treated hypertension very significantly reduces the risk of serious complications. The first step is often the simplest: measuring it regularly, to move past the silent uncertainty that characterizes this condition.

To take your own measurements, take the “Do I have high blood pressure?” test.