Implantation of an ICD did not significantly reduce sudden cardiac death (SCD) or hemodynamically significant ventricular arrhythmia (HSVA) compared with an implantable loop recorder (ILR) in patients with an LVEF of 36% to 50% and myocardial scar, based on results from the CMR GUIDE trial presented at ESC Congress 2026 and simultaneously published in JAMA.

Researchers randomized approximately 350 patients from 18 sites in Australia, Germany and the UK to either a primary prevention ICD or ILR. The median age of participants was 65 years, 18% were female, 72% had an ischemic etiology and 70% had an LVEF of 40% or greater. The media follow-up period was 6.3 years.

Overall results showed the primary outcome of SCD or HSVA occurred in 14 patients (7.8%) in the ICD group compared with 16 patients (9.2%) in the ILR group. Broken down by individual components, SCD occurred in 3 patients (1.7%) in the ICD group vs. 10 patients (5.8%) in the ILR group, while HSVA occurred in 12 patients (6.7%) vs. 6 patients (3.5%), respectively.

Researchers noted that the rates for all-cause mortality, cardiovascular mortality, and heart failure–related hospitalization were similar between the two groups. Additionally, a prespecified analysis of subgroups found the primary outcome occurred less often in patients younger than 70 years who received an ICD but not in those aged 70 years or older.

"Overall, the primary endpoint was neutral," said Principal Investigator Joseph Selvanayagam, MD, from Flinders University, Flinders Medical Centre in Adelaide, Australia. "However, younger patients appeared to derive clinical benefit from ICDs. We suggest that data from the CMR GUIDE trial are discussed with younger patients in whom ICDs may be an option in a shared decision-making process."

In a related editorial comment, Sana M. Al-Khatib, MD, FACC, highlights that "one of the main benefits of the CMR GUIDE trial is that it highlights the need for more randomized clinical trials of ICDs for primary prevention guided by LGE-CMR in patients with an LVEF greater than 35%." She stresses that "such data are urgently needed."

Clinical Topics: Cardiovascular Care Team, Heart Failure and Cardiomyopathies

Keywords: ESC Congress, ESC26, Cardiomegaly, Cardiomyopathies, Laminopathies, Congenital, Hereditary, and Neonatal Diseases and Abnormalities, Ventricular Dysfunction, Ventricular Dysfunction, Left, Cardiomyopathy, Dilated