Computer Tool Predicts Risk of Deadly Irregular Heart Beats

The tool, may help avoid unnecessary - and potentially risky - surgeries to place the devices.

The tool, developed by researchers at Johns Hopkins University in the US, may help avoid unnecessary - and potentially risky - surgeries to place the devices.

(Photo: iStockphoto)

Scientists have developed a computer system that can accurately predict which patients with a rare heart condition will suffer from a potentially fatal events, and whether they may benefit from life-saving implanted devices.

The tool, developed by researchers at Johns Hopkins University in the US, may help avoid unnecessary - and potentially risky - surgeries to place the devices.

An estimated 1 in 5,000 people have arrhythmogenic right ventricular cardiomyopathy (ARVC), a complex, multigene, inherited disease of the lower heart chambers that can cause deadly arrhythmias, or irregular heartbeats. Although rare, it is a very frequent cause of sudden death in young adults, researchers said.

The average age of diagnosis is 31, although it can emerge from adolescence through middle age.

ARVC can be effectively managed in many cases with an implantable cardioverter-defibrillator (ICD), a device that detects electrical abnormalities in heart muscle and immediately shocks the heart to re-establish normal rhythm.

ICDs prevent sudden cardiac death and save lives. However, these devices come with risks and side effects, said Cynthia A James, assistant professor at the Johns Hopkins University.

The devices may deliver inappropriate shocks when patients are not experiencing life-threatening arrhythmias. The ICD itself or pacemaker leads placed in the heart to deliver a shock may fail over time, necessitating replacement with surgery.

Infections brought on by these devices - and even just wearing out the device's battery with time - also require replacement, hospitalisations and expense, she added.

"Because patients develop this condition at such a young age, they typically need several ICD replacements over the course of their lives," said James.

"For ARVC patients, getting an ICD is a big decision with serious consequences," she said.

While physicians are generally in agreement that patients who experience a life-threatening arrhythmia qualify for an ICD, it has been unclear whether patients who have not yet experienced this event should get one for prevention.

Researchers pooled medical record data from 528 patients in five registries based at 14 academic medical centres in the US and Europe.

The group was nearly evenly split between male and female and between North America and Europe. None had yet experienced a life-threatening arrhythmia.

Then, using risk factors derived from published previous studies, researchers developed a computer-based mathematical set of consistent rules to try to predict whether any of the 528 patients might undergo a serious arrhythmia over time.

Over nearly five years of follow-up, just over a quarter of these patients experienced a dangerous arrhythmia, and 18 patients died.

The researchers found that their model accurately accounted for which patients would have life-threatening events. No patient with a five-year, model-predicted risk of five per cent or less had a serious arrhythmia.

More than 95 per cent of arrhythmias occurred in people with at least a 15 per cent five-year risk.

When the researchers compared their prediction accuracy rates with outcomes using a current consensus-based ICD placement algorithm, they found that about 20.6 per cent of recommended ICD placements would have likely been unnecessary.

"We believe our findings and the risk calculator we have developed have the potential to contribute to personalised medicine and to high value health care efforts emerging throughout medical care," said Hugh Calkins, professor at the Johns Hopkins University.

Researchers said it can cost USD 20,000 to implant an ICD and a similar amount of money to replace the device when the battery wears out five to 10 years later.