Identifying the vulnerable: navigating the predictors of implantable cardioverter defibrillator (ICD) therapy in the moderately reduced ejection fraction (EF) cohort
E Ahmed, M Abdelfattah, A Abdelsamed, S Gomaa Hasan, M M Abdelfadil, M S Riad, N K Abdelsattar, M Wanees Ahmed El Husseny, O KamelAbstract
Background
Implantable cardioverter defibrillators (ICDs) are vital in preventing sudden cardiac death, particularly in patients with severely reduced ejection fraction (EF ≤35%)1. However, the predictive factors for appropriate ICD therapy in patients with moderately impaired EF (35-50%) remain less defined. This population poses a unique challenge in risk stratification, given their intermediate ventricular function and variable arrhythmogenic substrate.
Objective
To identify robust clinical, imaging, and electrocardiographic predictors of appropriate ICD therapy in patients with EF between 35% and 50%.
Methods
We conducted a retrospective cohort study involving 49 ICD recipients of whom 96% were implanted for 2ry prevention with EF 35-50%, 50% of the patients was ischemic. Clinical characteristics, cardiac magnetic resonance imaging (CMR) parameters including strain measurements and baseline electrocardiographic measures were evaluated. Univariate and multivariable logistic regression analyses were employed to determine independent predictors of appropriate shock therapy. Receiver operating characteristic (ROC) curve analysis defined optimal cutoff values for continuous variables.
Results
During a mean follow-up period of 36 months, 41% of patients experienced appropriate ICD therapies. There was no significant difference observed between ischemic and non ischemic groups. Patients receiving appropriate therapy had a significantly higher prevalence of chronic total occlusion (CTO) of coronary arteries in the ischemic subgroup (42.9% vs. 8.7%, p=0.014). Moreover QT intervals were significantly prolonged in the therapy group (475.4 ms vs. 448.1 ms, p=0.016), accompanied by increased right ventricular end-diastolic volume (RVEDV) on CMR (215.9 mL vs. 154.9 mL, p=0.026). Multivariate analysis identified Two independent predictors: CTO (adjusted odds ratio [aOR] 32.11; 95% confidence interval [CI], 1.54–669.55; p=0.025), and QT interval prolongation (aOR 1.03 per ms increase; 95% CI, 1.00–1.05; p=0.036) (Table 1). ROC analysis for QT interval yielded an optimal cutoff of 438 ms, with 85.0% sensitivity and 51.7% specificity (area under the curve 0.696, p=0.021) (Figure 1). Importantly, measures of myocardial strain were not significantly different in both groups and did not predict appropriate ICD shocks. Moreover there was a tendency towards less appropriate therapy in those receiving Beta blockers (p=0.04), and Spironolactone (p=0.054). VT ablation was successful in 60% of patients receiving appropriate ICD therapies .
Conclusion
In patients with moderately reduced EF (35-50%), chronic total coronary occlusion, and a prolonged QT interval are robust, independently predict appropriate ICD ICD therapy. These factors can guide risk stratification in this intermediate-risk population beyond ejection fraction alone.Multivariable Logistic Regression AnalysROC Curve for QT