Inappropriate cardioverter-defibrillator discharge continues to be a major problem in clinical practice.

BACKGROUND The purpose of this study was to determine the rate and causes of inappropriate rhythm detection, and to compare adequacy of ventricular arrhythmia detection by single-chamber and dual-chamber cardioverter-defibrillators (ICD). METHODS We evaluated 190 patients (age 57.2 +/- 11.2 years) with ICD. FOLLOW-UP 34.3 +/- +/- 22 months. Dual-chamber ICD was used in 54 patients. RESULTS We evaluated 2244 arrhythmia events recognized as of ventricular origin, including ventricular tachycardia and ventricular fibrillation. 431 events (19.2%) were recognized erroneously and resulted in an inappropriate ICD discharge. Most cases of inappropriate therapies (182 events, 42.23%) were due to atrial fibrillation or flutter. Overall, inappropriate arrhythmia detection was found in 64 (33.6%) of 190 patients. In terms of the number of affected patients, the most common cause of inappropriate ICD discharge was sinus tachycardia - 23 (12.1%) patients, followed by atrial fibrillation - 16 (8.4%) patients. Among 54 patients with dual-chamber ICD, inappropriate therapy was noted in 21 (38.8%) patients, (T wave oversensing, sinus tachycardia and atrial fibrillation etc.). No significant difference was seen in the rate of inappropriate therapy due to a rapid supraventricular rhythm between patients with single-chamber versus dual-chamber ICD. In contrast, patients with single-chamber ICD more often experienced inappropriate therapy due to atrial fibrillation (155 vs. 28 patients) and sinus tachycardia (66 vs. 9 patients). CONCLUSIONS Despite of introduction of new generations of ICDs, the problem of inappropriate ICD discharge could not be eliminated. The major problem is distinction between supraventricular arrhythmia and ventricular tachyarrhythmia.