3D virtual heart to predict sudden cardiac death risk

Scientists have developed a new non-invasive, personalised 3D virtual heart assessment tool to help doctors determine whether a patient faces a risk of life-threatening arrhythmia.
When electrical waves in the heart run amok in a condition called arrhythmia, sudden death can occur, researchers said.
To save the life of a patient at risk, doctors currently implant a small defibrillator to sense the onset of arrhythmia and jolt the heart back to a normal rhythm.
However, it is difficult to decide which patients truly need the invasive, costly electrical implant.
"Our virtual heart test significantly outperformed several existing clinical metrics in predicting future arrhythmic events," said Natalia Trayanova from Johns Hopkins University in the US.

"This non-invasive and personalised virtual heart-risk assessment could help prevent sudden cardiac deaths and allow patients who are not at risk to avoid unnecessary defibrillator implantations," said Trayanova.

Researchers formed its predictions by using the distinctive magnetic resonance imaging (MRI) records of patients who had survived a heart attack but were left with damaged cardiac tissue that predisposes the heart to deadly arrhythmias.
The study involved data from 41 patients who had survived a heart attack and had an ejection fraction - a measure of how much blood is being pumped out of the heart - of less than 35 per cent.

Researchers used a pre-implant MRI scans of the recipients' hearts to build patient-specific digital replicas of the organs.
Using computer-modeling techniques, the geometrical replica of each patient's heart was brought to life by incorporating representations of the electrical processes in the cardiac cells and the communication among cells.
In some cases, the virtual heart developed an arrhythmia, and in others it did not. The result, a non-invasive way to gauge the risk of sudden cardiac death due to arrhythmia, was dubbed VARP, short for virtual-heart arrhythmia risk predictor, researchers said.
The method allowed the researchers to factor in the geometry of the patient's heart, the way electrical waves move through it and the impact of scar tissue left by the earlier heart attack.

"We demonstrated that VARP is better than any other arrhythmia prediction method that is out there," said Trayanova.
"By accurately predicting which patients are at risk of sudden cardiac death, the VARP approach will provide the doctors with a tool to identify those patients who truly need the costly implantable device, and those for whom the device would not provide any life-saving benefits," she said.
The findings were published in the journal Nature Communications.