Background: An algorithm based on the pattern of R-wave interval variability has recently been incorporated in the Medtronic Visia AF single lead ICD to improve detection of atrial fibrillation (AF) episodes. The differences between consecutive R-wave intervals are plotted in a Lorenz plot.
Objective: This nonrandomized, multicenter study aimed to quantify the performance of this algorithm by reviewing AF episodes in a population followed in 3 different centers.
Methods: The rate of occurrence of AF episodes and the percentage of appropriately detected AF were determined from 110 patients (age 60,18 ±12,84 years, male 80,0%) implanted with a Medtronic Visia AF single lead ICD that transmitted to CareLink over a 13,9 ±8,38-month period. Two experienced cardiologists reviewed the last 10 remote monitoring-transmitted EGMs diagnosed as AF.
Results: Episodes of AF were detected in 41 patients (37,3%). A total of 254 tachycardia episodes were reviewed. The overall accuracy of the device to correctly detect AF episodes was 39,37% since 154 (60,63%) of the episodes could be considered as inappropriate. Causes of false positive AF detections were runs of ectopy (premature atrial contractions 62,09%, premature ventricular contractions 35,29%) or irregular coupling intervals caused by underlying sinus variability (3,27%).
Conclusion: The dedicated-algorithm incorporated in the Medtronic single lead devices is associated with a high rate of incorrect AF diagnosis. Frequent premature atrial or ventricular contractions are primary causes of inappropriate atrial fibrillation detection. This may have clinical implications and may suggest required changes in the algorithm architecture.