Preventative care can be tricky when invasive procedures are involved. At what point does a doctor decide a costly, sometimes risky surgery is worth it to protect a patient from future issues? This is a common problem for clinicians dealing with patients at risk for arrhythmia, a condition in which electrical waves in the heart go haywire and cause an irregular heartbeat and, in some cases, sudden death. If physicians implant a defibrillator, it can shock a person’s heart back into a normal rhythm if they experience an irregular heartbeat. The implant is not without its own health risks, however. To tackle the problem, researchers from Johns Hopkins developed a tool to help doctors determine a patient’s risk for arrhythmia.

The team reported its efforts in a proof-of-concept study detailing a non-invasive, 3-D virtual heart assessment tool. The test yielded more accurate predictions of which patients would experience arrhythmia than the technique currently used by most physicians, an imprecise blood pumping measurement.

“Our virtual heart test significantly outperformed several existing clinical metrics in predicting future arrhythmic events,” Natalia Trayanova, a professor of biomedical engineering at Johns Hopkins, said in a press release. “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.”

Tyanova joined forces with cardiologist and co-author Katherine C. Wu, an associate professor at Hopkins, for the study. They led a team in using magnetic resonance imaging (MRI) records of patients who had survived a heart attack with damaged cardiac tissue, a risk factor for deadly arrhythmias. They used data from 41 patients who had an ejection fraction — a measure of how much blood is being pumped out of the heart — of less than 35 percent. The researchers went into their analysis blind, meaning they didn’t know during the study what ended up happening to the patients.

Usually, doctors recommend implantable defibrillators for any patient in this range, and all of those in the study received one. The research, however, suggested that this score may be a flawed measure of sudden cardiac death risk. The Hopkins team created an alternative to the scores based on pre-implant MRI scans of the patients and personalized, digital replicas of their organs. They then simulated the cardiac cells’ electrical processes and communications, bringing the computer models to “life.” Some of the replicas developed arrhythmia, and others did not. These hearts allowed the scientists to observe the geometry of the patients’ hearts, how electrical impulses moved through them, and what impact scar tissue had on arrhythmia risk.

They named the technique VARP, short for virtual-heart arrhythmia risk predictor.

When the researchers compared VARP’s prediction results with the patients’ records, the team found that those who tested positive for arrhythmia risk in the model were four times more likely to have developed arrhythmia than those who tested negative. VARP also asserted its dominance over the ejection fraction and other existing methods, predicting arrhythmia occurrence in patients four to five times better.

“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,” Trayanova said.

Wu voiced her agreement that these results, though early, could signal that VARP is a useful alternative to the broad ejection fraction score.

“As cardiologists, we obtain copious amounts of data about patients, particularly high-tech imaging data, but we ultimately use little of that information for individualized care,” she said. “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.”

Wu said testing with the virtual heart could save patients from invasive procedures, allowing for safer and more individualized risk assessment.

Looking ahead, the team hopes to conduct larger tests with VARP and determine its possibly life-saving abilities.

Source: Arevalo H, Vadakkumpadan F, Guallar E, Jebb A, Malamas P, Wu K, et al. Arrhythmia Risk Stratification of Patients After Myocardial Infarction Using Personalized Heart Models. Nature Communications. 2016.