The AHA now recommends treating high blood pressure when it measures over 130/80mmHg, which is lower than the previous limit of 140/90mmHg.
This is the first significant change in the US guidelines since 2003, and it will likely increase the number of Americans diagnosed with the condition from 32% to 46%.
Why have the US guidelines changed? And if Singapore will not be adopting the new high blood pressure definition, do the new US guidelines mean anything for you?
Dr Paul Chiam, cardiologist at Mount Elizabeth Novena Hospital, shares his thoughts and advice on the subject.
Blood pressure basics
Technically, doctors measure your blood pressure twice. Systolic pressure measures the pressure in the arteries as the heart contracts. Diastolic pressure measures the pressure in the arteries as the heart relaxes.
Normal blood pressure is generally considered to be a systolic pressure of less than 120mmHg, and a diastolic pressure of anything less than 80mmHg.
In the past, high blood pressure (medically known as hypertension) was not officially diagnosed until systolic pressure exceeded 140mmHg, or diastolic pressure exceeded 90mmHg. That's all changed with the new AHA guidelines.
In the new AHA guidelines, you are considered to have high blood pressure if your systolic high blood pressure is 130mmHg or higher, or diastolic pressure is 80mmHg or higher.
Why have blood pressure guidelines changed?
The Landmark Systolic Blood Pressure Intervention Trial (SPRINT), which was published in 2015, suggests that adults with high blood pressure continue to benefit when their systolic pressure is reduced to less than the norm (120mmHg).
Therefore, any systolic pressure measurement over 130mmHg puts a patient at a higher risk of heart disease and its various complications.
With the new guidelines, doctors can intervene at an earlier stage.
Are Singapore's high blood pressure guidelines changing?
Singapore is sticking to its definition of high blood pressure as when blood pressure is more than 140/90mmHg, said the Ministry of Health (MOH) on 16 Nov 2017.
The MOH explained that the AHA's guidelines were developed in the context of the US population and that it would continue to review its applicability to the Singapore population. They also noted that the revised guidelines do not change the approach to blood pressure management in a major way.
Dr Paul Chiam shares his thoughts: "The aim of the new guidelines is to increase awareness that a blood pressure of more than 130/80mmHg increases the risk of cardiovascular disease, and gives us impetus to be more aggressive with lifestyle modications such as diet, exercise and weight loss.
"For most of the general public, lifestyle modifications will suffice and medications will not be required if the BP is between 130 – 140/80 – 90mmHg."
For Singapore specifically, implementing these guidelines will come down to assessing the supporting evidence and determining whether it will benefit the population as a whole.
"In the meantime, the new AHA guidelines give everyone the important reminder that high blood pressure increases the risk of cardiovascular disease," says Dr Chiam. "While a diagnosis of 130/80mmHg blood pressure will not necessarily result in the need to take medication, it does show us the importance of leading a healthy lifestyle."
Exercising more, adopting a healthier diet, avoiding alcohol and foods high in salt, quitting smoking, losing weight and minimising stress can all help to reduce blood pressure.
For many people, these modifications will be enough to achieve a healthier reading. Dr Paul Chiam clarifies: "Your doctor will likely only recommend you take medication at this stage if you have already had a heart attack or stroke, or if you are a high risk of having one – for example, if you are diabetic."
What should you do if you are worried about your blood pressure?
It is always best to consult your doctor if you are concerned about high blood pressure, or if you have a family history of the disease.
They will assess you as an individual and identify the key medical issues that may be risk factors for you. To optimise quality and length of life, and reduce the risk of preventable disease-related complications such as heart attack, stroke and heart failure, they may suggest lifestyle changes in line with your health needs and goals.