Predictors of inappropriate shocks from implantable cardioverter-defibrillators

Introduction: Inappropriate shocks in patients with an implantable cardioverter-defibrillator (ICD) are associated with significant psychological and physical consequences and increased long-term mortality. The aim: To assess predictors associated with inappropriate high-energy discharges of implantable cardioverter-defibrillators.

Material and Methods: Retrospective data analysis of 150 patients aged 64.2±12.8 years (84.7% male) admitted to the Hospital Emergency Department due to at least one cardioverter-defibrillator discharge was performed. All of the discharges were inappropriate in the group of 33 patients, and in the group of 117 patients at least one discharge was appropriate. The following data: age, gender, concomitant diseases, type of ICD implantation (primary vs. secondary prevention), type of discharge, number of discharges, serum potassium, and sodium concentration were collected.

Results: Patients with only inappropriate discharges were younger, significantly more often had chronic atrial fibrillation, a significantly higher number of discharges, and ischaemic cardiomyopathy. Logistic regression analysis revealed that the occurrence of only inappropriate discharges was related to the number of discharges over three, the age of patients below 60 years, the serum sodium concentration between 135 mEq/L and 142 mEq/L, and the primary type of prevention of sudden cardiac death.

Conclusions: 1. Predictors of inappropriate discharges include: age, serum sodium concentration, and primary type of indications for cardioverter-defibrillator implantation. 2. Further research is necessary to determine the influence of disturbances in the sodium economy on the occurrence of appropriate and inappropriate interventions of implantable cardioverter-defibrillators.