Predictors of Appropriate ICD Therapy in Noncompaction Cardiomyopathy

Background Noncompaction cardiomyopathy (NCCM) is associated with ventricular arrhythmias and sudden cardiac death, but predictors of appropriate implantable cardioverter-defibrillator (ICD) therapy remain incompletely defined. Objective To identify markers of appropriate ICD therapy in ICD-treated NCCM, emphasizing primary-prevention recipients. Methods We performed a multicenter retrospective cohort study of adults with confirmed NCCM who underwent ICD implantation from 2002 to 2024 across three Mayo Clinic sites. The primary outcome was appropriate ICD therapy, defined as appropriate antitachycardia pacing and/or shock. Logistic regression and Cox models assessed predictors, including primary-prevention, implant-era, shock-only, and no pathogenic or likely pathogenic variant analyses. Results Among 141 patients, 47 (33.3%) experienced appropriate ICD therapy. Of 117 primary-prevention recipients, 31 (26.5%) experienced appropriate therapy. In overall adjusted logistic regression, male sex (adjusted odds ratio [aOR] 2.63; p=0.023), syncope (aOR 3.15; p=0.008), and right bundle branch block (aOR 2.65; p=0.033) were associated with appropriate therapy. Among primary-prevention recipients, syncope was associated with appropriate therapy (aOR 3.68; p=0.008) and shorter time to first appropriate therapy (hazard ratio [HR] 3.89; p=0.002). In shock-only analyses, syncope remained associated with appropriate ICD shock among primary-prevention recipients (OR 3.02; p=0.022; HR 3.42; p=0.005). Conclusion In ICD-treated NCCM, appropriate therapy occurred frequently, including in primary-prevention recipients. Syncope was the most consistent marker of subsequent and earlier appropriate therapy, supporting its importance in NCCM risk discussions.