Prophylactic ICD therapy did not reduce mortality in patients with a prior myocardial infarction (MI), persistent moderate left ventricular (LV) systolic dysfunction and abnormal ECG markers, according to results from the REFINE-ICD trial presented at ESC Congress 2025.

In total, nearly 2,000 patients with a prior MI (≥2 months) from Canada, the U.S., Europe, Middle East and Africa underwent ambulatory ECG testing to assess two markers of ventricular arrhythmia risk: heart rate turbulence and T wave alternans. Of these, 597 patients with LVEF 36-50%, impaired heart rate turbulence and abnormal T wave alternans were randomized to an ICD added to medical therapy or medical therapy alone. The mean age of the patients was 65 years and 19% were women. Overall mortality was higher in patients with both abnormal ECG markers compared with those without (hazard ratio [HR] 2.59; 95% confidence interval [CI] 1.97 to 3.40; p<0.001).

Over the mean follow-up period of approximately six years, total mortality was not reduced with ICDs. According to study investigators, 24.5% of patients died in the ICD group compared with 21.3% in the control group. Nearly half of the deaths (47.4%) were adjudicated as noncardiac deaths. Broken down by event, cardiac mortality was 8.8% in the ICD group compared with 7.6% in the control group. Sudden cardiac death occurred in 2.6% of patients in the ICD group and 3.8% in the control group.

"From earlier studies we knew that the risk of death was high after an MI, notably among patients with persistent, moderate LV systolic dysfunction and ECG markers associated with ventricular arrhythmia risk. We tested the hypothesis that an ICD may help these patients live longer than those who receive optimal medical therapy alone," said Principal Investigator Derek V. Exner, MD, FACC. "Importantly, ICD therapy did not reduce total mortality, cardiac death and sudden cardiac death. Further research efforts are needed to better manage these patients."