Ventricular Discordance as an MRI Phenotype Provides Prognostic Value Among Arrhythmogenic Cardiomyopathy.

Background: In arrhythmogenic cardiomyopathy (ACM), left ventricle-dominant presentation has poorer outcomes than right-dominant presentation, suggesting that interventricular functional disparity might play a role in patients' prognosis. However, the prognostic impact of ventricular functional discordance in ACM patients remains unknown.

Purpose: To assess whether ventricular functional disparity measured as ventricular discordance index, defined as the ratio of right-ventricular ejection fraction (RVEF) to left-ventricular ejection fraction (LVEF), might reveal prognostic disparities between phenotypes and offer added risk stratification value.

Study type: Retrospective.

Subjects: A total of 222 patients with ACM (mean age 44 ± 16 years, 144 males) from three centers were included.

Field strength/sequence: 3-T, cine imaging.

Assessment: Ventricular discordance index was calculated using cine-derived RVEF and LVEF, for which a threshold was determined using Youden J index. Clinically ventricular discordance was defined as ventricular discordance index above the threshold. The major adverse cardiac events (MACE), was defined as sudden cardiac death, appropriate implantable cardioverter-defibrillator intervention, and aborted cardiac arrest. International task diagnostic force criteria and the 5-year risk score were evaluated.

Statistical tests: The prognostic implications of ventricular discordance index and clinically ventricular discordance were evaluated using multivariable Cox analysis. P < 0.05 indicated the statistical significance.

Results: During a median follow-up of 50 months, 81 (37%) patients experienced MACE. The ventricular discordance index was independently associated with MACE (hazard ratio [HR]: 1.49; 95% confidence interval [CI]: 1.23-1.82). Patients classified under clinically ventricular discordance experienced higher MACE rates and were less likely to meet the task force structural criteria. clinically ventricular discordance was independently associated with MACE (adjusted HR: 2.2; 95% CI: 1.36-3.55). Clinically ventricular discordance, LV involvement and the 5-year risk score in combined reclassified 20.3% of patients compared to 2015 task force classification.

Data conclusion: Ventricular discordance was associated with MACE in ACM, potentially providing prognostic value beyond the 5-year risk score.

Level of evidence: 3 TECHNICAL EFFICACY: 5.