Fatal end of a safety algorithm for pulmonary vein isolation with use of high-intensity focused ultrasound.
BACKGROUND
High-intensity focused ultrasound (HIFU) can achieve pulmonary vein isolation (PVI), but there are safety concerns after severe complications. Therefore, we evaluated an esophageal temperature (ET)-guided safety algorithm to apply HIFU safely.


RESULTS
After standard left atrial access, HIFU was repeatedly applied until PVI was complete. A safety algorithm was used: <or=3 complete ablations per pulmonary vein (PV), early abortion when no effect after 50%of programmed time or when ET was >or=40.0 degrees C, use of power modulation (PM) at ET 39.0 degrees C: to reduce ablation temperature in surrounding tissue, acoustic power is switched on/off at 1 Hz; in all first ablations, use of PM after 50% of programmed time. Touch-up radiofrequency ablation was used when PVI failed. Periprocedural ET monitoring and endoscopy 2 days after ablation were performed. Twenty-eight patients (18 males; mean age at enrollment, 63 years), with paroxysmal atrial fibrillation (AF; n=19) and persistent AF (n=9) were included. In 84 of 109 PV (9 of 25 patients), PVI was achieved using HIFU only. In 9 of 109 PV, HIFU was aborted because of high ET. Mean ET at the end of the ablations with and without use of PM were 38.1+/-2.0 degrees C and 37.4+/-1.0 degrees C (P=0.0002). During endoscopy in 2 of 26 patients, a small thermal lesion was found. Other complications included 2 persistent phrenic nerve palsies, 1 ischemic stroke, 1 pericardial effusion 48 days after ablation, 1 unexplained death 49 days after ablation, and 1 lethal atrial-to-esophageal fistula 31 days after ablation.


CONCLUSIONS
The safety algorithm failed to prevent lethal complications. Currently HIFU does not meet the safety standards required for treatment of atrial fibrillation.
Neven
Kars
K
Asklepios Klinik St Georg, Department of Cardiology, Hamburg, Germany.
Schmidt
Boris
B
Metzner
Andreas
A
Otomo
Kiyoshi
K
Nuyens
Dieter
D
De Potter
Tom
T
Chun
K R Julian
KR
Ouyang
Feifan
F
Kuck
Karl-Heinz
KH
D000368:Aged; D000465:Algorithms; D001281:Atrial Fibrillation / Q000401:mortality / Q000503:physiopathology / Q000601:surgery*; D001833:Body Temperature Regulation; D002545:Brain Ischemia / Q000209:etiology; D017115:Catheter Ablation / Q000009:adverse effects / Q000379:methods* / Q000401:mortality; D004937:Esophageal Fistula / Q000209:etiology / Q000401:mortality; D004945:Esophagoscopy; D004947:Esophagus / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative / Q000379:methods*; D010243:Paralysis / Q000209:etiology; D010490:Pericardial Effusion / Q000209:etiology; D010791:Phrenic Nerve / Q000293:injuries; D011237:Predictive Value of Tests; D011446:Prospective Studies; D011667:Pulmonary Veins / Q000503:physiopathology / Q000601:surgery*; D018570:Risk Assessment; D020521:Stroke / Q000209:etiology; D016896:Treatment Outcome; D014464:Ultrasonic Therapy / Q000009:adverse effects / Q000401:mortality