Doctors here have discovered a new way of identifying which patients with hypertension are at risk of heart failure, even before they show symptoms.
Hypertension or high blood pressure is not known as the silent killer for nothing. It is difficult to spot because most patients do not have any symptoms.
Even when they are diagnosed and on medication, they only realise all is not well when complications arise.
Now, doctors at the National Heart Centre Singapore (NHCS) may have found a solution.
In a discovery that is understood to be a world’s first, they have pinned down a way of identifying patients with hypertension who are on the brink of developing complications, and this is even before symptoms appear.
It is done through an easily calculated ratio called the Remodelling Index, which potentially can lead to new treatments and fewer deaths (see box).
Decompensation? What’s that?
Hypertension itself does not kill, but complications such as heart failure can be fatal.
High blood pressure makes the heart muscle work harder. And as it works harder, it grows in size, just like any other muscle in the body.
In some patients, this increase in muscle mass turns abnormal, and becomes what is known as left ventricular hypertrophy. In a small number of people, the heart eventually becomes unable to cope anymore. That is when patients develop heart failure and other heart relatedcomplications.
That tipping point is known as decompensation.
“But no one knows when decompensation is going to happen. Right now, we can only diagnose and treat patients after they develop symptoms of heart failure,” said Dr Calvin Chin, Consultant, Department of Cardiology, NHCS, and lead investigator of the study.
A useful tool
Here’s where the possible solution comes in.
Known as the Remodelling Index, it is taken from a biophysical law describing how the heart responds to increased stress. The harder it is for the heart to cope, the lower the Remodelling Index will be.
“Using this Remodelling Index, we can potentially identify which patients are in the early stages of decompensation even if they don’t have any symptoms of heart failure yet,” said Dr Chin.
In Singapore, where hypertension is common, and one in two adults above 60 have it, this is a useful tool.
Dr Chin said that because it is a lifestyle disease, food choices, smoking and insufficient exercise result in more younger adults being affected by it.
Patients with hypertension take medication to control their blood pressure. But there are no specific drugs targeted to reduce left ventricular hypertrophy. However, research is ongoing, and there could be one available in the near future.
“But even if there’s a new drug, we can’t treat everyone with left ventricular hypertrophy because we may end up over-treating some people, when actually a lot of them may be stable,” said Dr Chin.
“With the Remodelling Index, we can potentially target specific treatment to just the at-risk group, before heart failure occurs.”
How it works
This is how the study was done.
First, normal Remodeling Index was established in 180 healthy volunteers.
The Index decreases with age, and men have a lower Index than women.
A total of 256 patients with hypertension were checked using the Index, and around 6 per cent of them had lower than normal numbers.
When these patients were examined further, they were found to have left ventricular hypertrophy, more fibrosis (scarring of the heart muscle tissue) and higher blood markers indicating heart muscle injury. In fact, they were in the early stages of heart failure, although symptoms had not appeared yet.
The findings were published in the leading cardiology journal Circulation: Cardiovascular Imaging in August 2017.
There are already plans to take the idea further. Over the next few years, the team intends to see if low Index numbers coincide with the rapid progression of left ventricular hypertrophy, which eventually leads to heart failure and other heart-related complications.
“The ultimate aim is to establish the Remodelling Index as a good marker to monitor the progression of the disease and the patient’s response to treatment, so that personalised treatment can be given to our hypertensive patients. This is an active area of future research,” said Dr Chin.
Why assessing high blood pressure is challenging
Several issues make treating hypertension a challenge. They include:
Determining blood pressure accurately
Blood pressure fluctuates all the time. Numbers differ, depending on whether the person measured is calm, anxious, sitting, on the go, at home, in the clinic, and so on.
Differing baseline values
While the norm is accepted as 120/80 mmHg, for some people it may be lower or higher. So treatment that is based on achieving a fixed target may not be the right way to manage all hypertensive patients.
Differing blood pressure targets
There are different guidelines offered by the various authorities. The American Heart Association/ American College of Cardiology recently announced that 130/80 mmHg is the new “high” instead of the 140/90 adopted by most other cardiac societies. Singapore authorities are cautious about adopting these new targets, as more evidence of lower blood pressure in the local population is still needed.