Intrinsicoid Deflection of the QRS Complex Predicts Appropriate Antitachycardia Pacing or Shock Therapy in Heart...

Sudden cardiac death remains a significant risk for patients with heart failure (HF). Current guidelines recommend implantable cardioverter defibrillator (ICD) for patients with low left ventricular ejection fraction (LVEF). However, the effectiveness and necessity of ICDs in patients with normal LVEF raise questions, especially given associated complications and costs.

This study aims to evaluate the electrocardiographic predictors of appropriate ICD therapy (antiTachycardia pacing [ATP]/shocks) in patients with HF.

We conducted an analysis of 160 consecutive HF patients (New York Heart Association class I-III, LVEF ≤ 35%) undergoing ICD controls from January 2023 to December 2024. Patients were classified into two groups based on the occurrence of appropriate ATP or ICD shocks. Electrocardiographic parameters including QRS duration, QTc interval, intrinsicoid deflection (ID), and fragmented QRS (fQRS) were assessed. Statistical analyses, including receiver operating characteristic curves and logistic regression, were performed to identify independent predictors of appropriate ICD therapy.

The ATP/shock group exhibited significantly prolonged QRS and QTc intervals, increased ID, and higher Selvester scores compared to the non-shock group. Notably, an ID > 50 ms emerged as a strong predictor of ICD therapy (sensitivity 96.3%, specificity 95.3%). Univariate and multivariate analyses identified ID, fQRS, and Selvester score as independent predictors of appropriate ICD therapy.

Elevated ID, alongside other electrocardiographic parameters, serves as a valuable predictor for appropriate ICD therapy in HF patients. These findings support the potential for refining ICD implantation criteria, emphasizing the importance of detailed electrocardiographic evaluation in predicting arrhythmic events.