Factors influencing the status of appropriate and inappropriate shocks delivered by an implantable cardioverter defibrillator

The QRS duration is a strong predictor of mortality, particularly in heart failure patients. However, studies on the usefulness of QRS duration, as a predictor of ventricular arrhythmic events in ICD patients, have proved to be contradictory. Since in patients with implantable cardioverer defibrillator (ICD), all of the malignant ventricular arrhythmias are recorded and treated with appropriate shock (i.e. appropriate shock and inappropriate shock), in the present study the relationship between the QRS duration and status of appropriate or inappropriate ICD shocks was evaluated. In this cross-sectional study 65 patients with implanted ICD were included to prevent their undue death. Before the implantation, QRS duration in the surface ECG was measured and recorded. Furthermore, variables such as age, gender, indication for ICD implantation, family history of sudden cardiac death, and QTc interval before ICD implantation were recorded. During follow-up visits of the patients, ICDs were interrogated and appropriate and inappropriate therapies were traced. Finally logistic regression in SPSS statistical software (V: 11.5) was used for data analysis. Mean age of the patients was 17.208±47.92 years. Eighteen patients (27.7%) were females and 58 (89.2%) had a family history of sudden cardiac death. Mean QRS duration and QTc interval were 36.78±117.94 msec and 62.42±466.97 msec, respectively. There was no statistically significant relationship between QRS duration and status of appropriate and inappropriate ICD shocks. Among the studied parameters, there was only a significant relationship between status of appropriate or inappropriate ICD shocks and the different manufacturers of ICD devices. QRS duration does not have a significant relationship with status of appropriate and inappropriate ICD shocks. This may not predict arrhythmic events in ICD patients.