Implantable cardioverter-defibrillators may benefit certain younger patients with mild–moderate heart dysfunction

A more than a decade-long medical trial has opened the way for potentially life-saving treatment options for patients with mild-to-moderate heart conditions. Internationally recognized cardiac expert Flinders University Professor Joseph Selvanayagam, from Adelaide’s Heart & Vascular, presented his findings at the European Society of Cardiology Congress (ESC 2026) in Munich on Friday. The breakthrough has also been published in JAMA.

The trial, involving 18 sites across Australia, Germany and the United Kingdom, examined whether a medical device currently used for patients with severe heart conditions could treat a wider range of patients.

An implantable cardioverter-defibrillator (ICD) is a small device placed in the body that can detect and correct dangerous heart rhythms that may otherwise cause sudden cardiac death. ICDs are currently offered only to patients with severely reduced heart function.

Selvanayagam’s research investigated another group of patients with mild-to-moderate heart dysfunction; a left ventricular ejection fraction (LVEF of 36%–50%); and scarring in the heart muscle identified by cardiac MRI. The trial examined whether ICD implantation could reduce sudden cardiac death or serious ventricular arrhythmia in this group of patients.

While the trial did not identify a statistically significant reduction with ICD use in the primary endpoint of sudden cardiac death or serious ventricular arrhythmia across all age groups, it did so in a prespecified analysis of patients younger than 70 years. Further, ICD implantation was associated with a reduction in the secondary endpoint of sudden cardiac death in the total cohort. This is the first randomized trial designed to help inform clinicians deciding about ICD implantation in patients with heart scarring and an LVEF of 36%–50%.

“An ICD is like having a personal paramedic for your heart, 24/7,” Selvanayagam said. “But the treatment gap right now is that most patients who die suddenly from a heart event don’t have underlying severe heart dysfunction, so currently don’t get offered an ICD because it is outside accepted treatment guidelines.

“This research has made a new finding that could potentially save lives. The reduction in sudden cardiac death and the benefit observed in younger patients provide important insights for individual treatment decisions.

“If you have mild to moderately reduced heart function due to a cardiomyopathy or previous heart attack, then you should have a cardiac MRI. If you then have significant scarring in your cardiac MRI, you should probably have a discussion with your cardiologist about whether an ICD should be implanted, particularly if you are younger than 70 years.”

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