Primary Prevention ICD Implantation in Non-ischemic Cardiomyopathy Patients: A Retrospective Analysis Applying the 2023 Dutch Society of Cardiology Guidelines (RF_TH_260)

In recent years, there has been growing controversy over the usefulness of implanting primary prevention implantable cardioverter defibrillators (ICDs) in patients with heart failure and a reduced ejection fraction caused by non-ischemic cardiomyopathy (NICM). In the Netherlands, new national guidelines for primary prevention ICD implantation in NICM patients have been introduced, which differ from the European Society of Cardiology (ESC) guidelines. Unlike the ESC guidelines, the Dutch guidelines emphasize cardiac magnetic resonance imaging (CMR)-identified fibrosis as a crucial criterion for ICD implantation. Given these recent changes in guideline interpretation, it is essential to assess the impact of the more stringent Dutch approach on patient outcomes. This exploratory single-center study aims to retrospectively apply the 2023 national guidelines, which include late gadolinium enhancement (LGE) assessment on CMR, to NICM patients who have previously received an ICD based on the ESC guidelines.

Methods:

This study included patients with NICM who received a primary prevention single-chamber, dual-chamber, or subcutaneous ICD between January 2008 and April 2022 and underwent LGE-CMR prior to implantation. Patients were classified into LGE+ and LGE- groups based on the presence of LGE detected by CMR. The primary endpoint was time to first appropriate ICD therapy and the secondary endpoint included all-cause mortality.

Results:

Of the 258 NICM-patients in the database, a total of 85 patients were included (Figure 1), of whom 41 had presence of LGE on CMR. Typical non-ischemic LGE distribution patterns included septal midwall LGE, hinge point LGE, and epicardial LGE. After a 5 year follow up period, appropriate ICD therapy occurred in 20% of patients in the LGE+ group and 14% of patients in the LGE- group (p=0.36 by log-rank test) (Figure 2). Multivariable analysis showed no parameters significantly associated with appropriate ICD therapy. All-cause mortality was 7% in the LGE+ group and 14% in the LGE- group (p=0.46 by log-rank test) (Figure 3).

Conclusion:

In this single-center retrospective cohort study of selected patients with NICM, approximately 50% exhibited LGE on CMR imaging. Over a 5-year follow-up period, 17% of patients received appropriate ICD therapy, while all-cause mortality was noted in 10% of the cohort.

Interestingly, there was no significant difference in the rates of appropriate ICD therapy or all-cause mortality between patients with LGE and those without LGE. The lack of significant prognostic differentiation between LGE+ and LGE- groups challenges the assumption that LGE alone should dictate the clinical decision-making process regarding ICD implantation in NICM patients. Notably, 14% of patients without LGE experienced appropriate ICD therapy. Further studies are needed to refine risk stratification strategies and to identify additional biomarkers or imaging features that may better predict outcomes in this patient population.