Failure of Complete Endothelialization of a Watchman Device 3 Years Post-Implantation.

We report an unusual case of incomplete endothelialization of the Watchman device >3 years after its implantation. Animal data suggest that device endothelialization occurs ∼45 days post-implantation; however, data on humans are lacking. Guidelines on anticoagulation are based on expectation from animal studies. (Level of Difficulty: Advanced.).

Utility of Contact Impedance Mapping in Differentiating the Mechanism of Focal Atrial Tachycardia.

Contact impedance mapping can differentiate focal atrial tachyarrhythmias from macroreentry (atrial flutter) and localized reentry (atrioventricular nodal reentry tachycardia) by detecting different patterns of regional unipolar tissue impedance distribution. Specifically, focal atrial tachycardia (AT) is characterized by the finding of a contiguous low-impedance area (CLIA) adjacent to the site of origin, surrounded by normal tissue impedance levels. However, it remains unclear whether or not this finding could distinguish different mechanisms of focal AT. In the present study, we sought to determine whether impedance and voltage maps in patients with microreentrant AT differ from those created due to triggered activity. Consecutive patients undergoing electrophysiologic study and the ablation of AT were included. All patients underwent mapping and ablation procedures in a standard manner. Contact impedance and voltage maps were collected in the background and analyzed offline for comparison. A total of 50 patients with 75 focal ATs were studied and ablated, and the mechanism of AT (ie, triggered activity versus microreentry) was determined. The 41 ATs attributed to triggered activity in 30 patients all demonstrated a CLIA containing or adjacent to the successful ablation site, while the 34 ATs in the 20 patients attributed to microreentry demonstrated uniform impedance. In contrast, microreentrant AT patients were more likely to have scar located adjacent to the site of origin (88.9% versus 18.2%). Three-dimensional mapping employing both contact impedance mapping and voltage mapping can reliably identify the mechanism of focal AT.

Usefulness of radiofrequency ablation of supraventricular tachycardia to decrease inappropriate shocks from implantable cardioverter-defibrillators.

Inappropriate implantable cardioverter-defibrillator (ICD) therapies can lead to significant adverse events and increased mortality. These therapies are often the result of supraventricular tachycardias (SVTs). The objective of this study was to evaluate the incidence of SVT leading to inappropriate shocks in a large cohort of patients with ICDs and assess the efficacy of radiofrequency ablation (RFA) in decreasing these therapies. Patients with ICDs and recurrent SVTs were identified. A cohort of patients with ICD therapies subsequently underwent electrophysiologic study and RFA. Eighty-four patients (13%) were found to have SVT leading to 122 inappropriate ICD shocks and 130 episodes of antitachycardia pacing therapies. Median time to SVT onset after ICD implantation was 269 days. Electrophysiologic studies were performed in 30 patients. Successful RFA was performed for atrial tachycardia, atrial flutter, or atrioventricular nodal reentrant tachycardia in 22 patients. Ninety-five percent of patients who underwent successful SVT ablation had no further inappropriate ICD therapies compared to 63% of patients in whom ablation was not performed during a mean follow-up of 20.7 ± 11.9 months. In conclusion, SVT is responsible for a significant number of inappropriate ICD therapies. RFA is an effective strategy to substantially decrease subsequent inappropriate ICD therapies.