A new test has been launched to detect inherited heart conditions, which affect more than half a million people in the UK.
The genetic test - which is cheaper, easier to use and picks up more problems than existing tests - is already in use in one NHS hospital, but is expected to be taken up by others.
Researchers funded by the British Heart Foundation (BHF) developed the blood test, which detects all known inherited heart condition genes.
Current tests examine a smaller number of genes and are only able to identify specific conditions.
Last month, the BHF launched the Miles Frost Fund in memory of Sir David Frost's son, Miles, who died suddenly last year of an undiagnosed heart condition called hypertrophic cardiomyopathy (HCM).
The family believes Miles inherited HCM from his father.
Inherited heart conditions can affect people of any age and can be life-threatening.
For many people, the first sign that they have an inherited heart condition is when a member of their family dies suddenly with no obvious explanation.
Genetic testing of family members can pinpoint faulty genes, therefore leading to the possibility the person can be treated to cut their chance of early death.
The new test looks at 174 genes and is currently being used by the Royal Brompton and Harefield NHS Foundation Trust.
Dr James Ware, from the Royal Brompton, said: "Genetic tests are invaluable when managing inherited heart conditions. They can help to make the initial diagnosis, and to choose the best treatment for the affected person. But where they make the biggest impact is in looking after that person's family.
"Without a genetic test, we often have to keep the whole family under regular surveillance for many years, because some of these conditions may not develop until later in life. This is hugely costly for both the families and the health system.
"By contrast, when a genetic test reveals the precise genetic abnormality causing the condition in one member of the family, it becomes simple to test other family members. Those who do not carry the faulty gene copy can be reassured and spared countless hospital visits.
"This new comprehensive test is increasing the number of families who benefit from genetic testing."
Professor Peter Weissberg, medical director at the BHF, said: "Collectively, inherited heart conditions represent a major cause of heart disease and are often the cause of an unexplained sudden death in a young person.
"As research advances and technology develops, we are identifying more and more genetic mutations that cause these conditions. In this rapidly evolving field of research the aim is to achieve ever greater diagnostic accuracy at ever-reducing cost."