Factors Associated with Implantable Cardioverter-defibrillator Shocks in Patients Suffering from Non-ischemic Cardiomyopathy

Background: Although intra-cardiac shocks are a lifesaving approach in patients with systolic heart failure (HF), the probable effective factors related to shock occurrence are less frequently recognized. We designed this study to assess the factors associated with inappropriate or appropriate implantable cardioverter-defibrillator (ICD) shocks in patients with non-ischemic cardiomyopathy (NICM).

Methods: Ninety-nine patients with NICM who implanted ICD were enrolled from March 2018 to September 2019 and followed up with a three-month interval for up to one year. Shock therapy was defined as either appropriate or inappropriate shock. The odds ratio (OR) of inappropriate shock occurrence was calculated with crude and different adjusted models.

Results: The mean age of the population at baseline was 51.9 ± 15.4 years (men: 71%). Baseline data revealed that patients with inappropriate shocks had higher heart rates (HR), worse New York Heart Association (NYHA) class, and anti-tachycardia pacing (ATP) as well as higher percentages of amiodarone usage compared to groups with appropriate or no shock [HR: 96.8 ± 27.8 vs. 79.8 ± 12.1 vs. 76.2 ± 17.6 beats per minute (bpm), P = 0.014; NYHA class IV: 85.7% vs. 74.1% vs. 63.4%, P = 0.041; ATP: 37.5% vs. 29% vs. 5%, P = 0.010; amiodarone usage: 37.5% vs. 25.8% vs. 5%, P = 0.23, respectively]. Further multiple-adjusted OR did not reveal any significant independent association between the aforementioned variables and inappropriate shock incidence.

Conclusion: This study indicates no significant independent predisposing factor in the occurrence of inappropriate shocks among patients with NICM. Other studies are required in this regard.