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.