Arrhythmias & electrophysiology

Cardiovascular Magnetic Resonance to Guide Defibrillator Implantation for Left Ventricular Ejection Fraction (LVEF) of 36% to 50%%: The Cardiovascular Magnetic Resonance (CMR) GUIDE Randomized Clinical Trial

JAMAPublished Randomised controlled trial

Primary resultResult — go to the resultHazard ratio 0.76 95% CI 0.37–1.58

Authors' conclusion

Implantation of an ICD did not reduce the composite outcome of SCD or HSVA in patients with an LVEF of 36% to 50% and myocardial scar.

Study context

Population
Adults with ischaemic or nonischaemic cardiomyopathy, LVEF 36% to 50%, CMR-defined myocardial scar, on guideline-directed medical therapy
Participants
353 adults
Comparison
Primary prevention ICD vs implantable loop recorder
  • ICDn = 180
  • Implantable loop recorder (ILR)n = 173reference
Primary endpoint
Sudden cardiac deaths (SCD) or hemodynamically significant ventricular arrhythmia (HSVA) (composite)
Methodological detailsopen-label, 18 sites in Australia, Germany and the UK
  • Open-label
  • 18 sites in Australia, Germany and the UK

Primary result

As reported in the abstract

Hazard ratio

0.76

95% CI 0.37–1.58

Events by treatment group

ICDvs ILR
HR 0.76 (95% CI 0.37–1.58)

Secondary outcomes

OutcomeICDILRHR (95% CI)
SCD1.7%5.8%0.26 (0.07–0.95)
HSVA6.7%3.5%1.77 (0.65–4.81)
Primary outcome, by age (prespecified subgroup)Age <70 years3.3%10.0%0.28 (0.09–0.89)
Primary outcome, by age (prespecified subgroup)Age ≥70 years16.9%7.5%2.33 (0.75–7.26)
  • Primary outcome, by age (prespecified subgroup): P = .01 for interaction

All-cause mortality, CV mortality, HF hospitalisation

Similar between groups

Original publication

Cardiovascular Magnetic Resonance to Guide Defibrillator Implantation for LVEF of 36% to 50%%: The CMR GUIDE Randomized Clinical Trial. JAMA. Published 28 August 2026. doi:10.1001/jama.2026.17078

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