THE RELATIONSHIP BETWEEN EPISODE FREQUENCY AND FUNCTIONAL CAPACITY IN PATIENTS TREATED WITH IMPLANTABLE CARDIOVERTER DEFIBRILLATORS

Introduction: Left ventricular ejection fraction (EF) is an important parameter for determining the frequency of ventricular arrhythmia episodes in patients treated with implantable cardioverter defibrillators (ICD). However, the relationship between heart failure and ICD episode frequency is controversial. This study aimed to evaluate the relationship between ICD episode frequency and functional capacity in patients classified according to the New York Heart Association (NYHA). Methods: The frequency of ventricular arrhythmia episodes was examined in patients who had a ICD implanted between January 1998 and April 2004. Seventy consecutive patients were retrospectively reviewed. Class I-II, II, and II-III patients were grouped into Group A, and Class III patients were grouped into Group B. The patients' demographic data, echocardiography findings, EFs, NYHA clinical status, indications for ICD implantation, and ICD episodes were examined. Results: The mean follow-up period for patients was 3.08±1.31 years. Two patients were NYHA class I-II, 15 patients were NYHA class II, 41 patients were NYHA class II-III, and 12 patients were NYHA class III. A total of 791 appropriately treated episodes of sustained ventricular tachycardia or ventricular fibrillation were observed in 70 patients. When these episodes were analyzed according to NYHA group, the frequency of ventricular arrhythmia episodes was higher in the Group B patient group (8.36±21.18 vs 25.33±27.63, p=0.019). Conclusions: NYHA class III heart failure is an easily assessable clinical measure and an important risk factor for the need for ICD treatment of ventricular arrhythmias. The rate of benefit from ICD treatment is higher in patients in the NYHA class III group.