In order to better determine which cardiac patients are at risk for life-threatening arrhythmia and need a defibrillator, a team of Johns Hopkins University researchers has created a groundbreaking, non-invasive 3-D virtual heart assessment tool. The device is more accurate at predictions than the imprecise blood pumping measurements currently used by physicians.
"Our virtual heart test significantly outperformed several existing clinical metrics in predicting future arrhythmic events," said Natalia Trayanova of Johns Hopkins University and senior author of the report. "This non-invasive and personalized virtual heart-risk assessment could help prevent sudden cardiac deaths and allow patients who are not at risk to avoid unnecessary defibrillator implantations."
Trayanova and her team formed their predictions using magnetic resonance imaging (MRI) records of patients that had survived a heart attack but possessed damaged cardiac tissue, which increases the likelihood of deadly arrhythmias. They examined 21 patients and had an ejection fraction - the measure of how much blood is being pumped out of the heart - of less than 35 percent.
Although all 41 patients in the study previously received implantable defibrillators to measure their ejection fractions, the team determined that this score is actually unreliable in its ability to predict patients that are at the most risk of sudden cardiac death.
The team used pre-implant MRI scans to create an alternative way to obtain these scores: a 3-D virtual heart assessment tool. Using the scans, they created patient-specific digital replicas of the organs and brought these replicas to life using computer-modeling techniques that took into account electrical processes in the heart and communication among cells.
The end result is a virtual heart that offers doctors a non-invasive way to determine the risk of sudden cardiac death due to arrhythmia. The team has named the device the virtual-heart arrhythmia risk predictor (VARP).
In addition, the team determined that VARP predicted arrhythmia occurrence in patients four-to-five times better than other commonly used clinical risk predictors.
"We demonstrated that VARP is better than any other arrhythmia prediction method that is out there," Trayanova said. "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."
"With the technique used in this study, we were able to create a personalized, highly detailed virtual 3-D heart, based on the patient's specific anatomy," added Katherine Wu, also of Johns Hopkins University and co-author of the study. "Then, we were able to test the heart virtually to see how irritable it is under certain situations. We could do all this without requiring the patient to undergo an invasive procedure. This represents a safer, more comprehensive and individualized approach to sudden cardiac death risk assessment."
The proof-of-concept report of the findings was published on May 10 in the journal Nature Communications.
