title: Two-year clinical follow-up after pulmonary vein isolation using high-intensity focused ultrasound (HIFU) and an esophageal temperature-guided safety algorithm.
abstract: OBJECTIVE
  High-intensity frequency ultrasound (HIFU) can achieve pulmonary vein isolation (PVI), but severe complications have happened. An esophageal temperature (ET)-guided safety algorithm was implemented. We investigated medium-term outcome.
  
  
  METHODS
  After left atrial access, HIFU was applied until complete PVI. The safety algorithm was as follows: ≤3 complete ablations per pulmonary vein, early abortion when ET ≥40.0°C, use of Power Modulation at ET >39.0°C or when after 20 to 30 seconds no change in PV electrograms: to reduce the ablation temperature in the surrounding tissue, acoustic power is switched on and off with a frequency of 1 Hz; in all first ablations, use of Power Modulation after 50% of programmed time. Touch-up radiofrequency ablation when PVI failed. Follow-up included interviews and Holter electrocardiograms. Recurrence was defined as atrial fibrillation (AF) >30 seconds without a blanking period.
  
  
  RESULTS
  A total of 28 symptomatic patients (18 males, age 63 years), with paroxysmal AF (n = 19) and persistent AF (n = 9) were included. After a median follow-up of 738 days, 22 of the 28 patients (79%) were free of AF without antiarrhythmic drugs. After 1 repeat procedure with radiofrequency ablation, 5 patients remained free of AF. The complications were as follows: 1 lethal atrial-to-esophageal fistula at day 31, 1 pericardial effusion at day 48, 1 unexplained death at day 49, and 2 persistent phrenic nerve palsies with full recovery within 12 months.
  
  
  CONCLUSIONS
  Two-year follow-up after PVI using HIFU and an ET-guided safety algorithm shows success rates similar to those of radiofrequency-based procedures but with higher complication rates. Importantly, the ET-guided safety algorithm failed to prevent severe complications. HIFU does not meet safety standards required for the treatment of AF, and this led to a halt of its clinical use.
authors: Department of Cardiology, Asklepios Klinik St. Georg, Hamburg, Germany. kars_neven@hotmail.com
authors: Kars
authors: K
authors: Neven
authors: Andreas
authors: A
authors: Metzner
authors: Boris
authors: B
authors: Schmidt
authors: Feifan
authors: F
authors: Ouyang
authors: Karl-Heinz
authors: KH
authors: Kuck
mesh_terms: D000465:Algorithms; D000889:Anti-Arrhythmia Agents / Q000627:therapeutic use; D001281:Atrial Fibrillation / Q000503:physiopathology / Q000628:therapy*; D017115:Catheter Ablation / Q000009:adverse effects / Q000379:methods; D015716:Electrocardiography, Ambulatory; D004869:Equipment Safety; D004947:Esophagus / Q000503:physiopathology; D005260:Female; D005500:Follow-Up Studies; D006329:Heart Conduction System / Q000503:physiopathology / Q000601:surgery; D006358:Hot Temperature / Q000009:adverse effects*; D006801:Humans; D007431:Intraoperative Complications / Q000209:etiology / Q000517:prevention & control; D008297:Male; D008875:Middle Aged; D008991:Monitoring, Physiologic / Q000379:methods; D011667:Pulmonary Veins / Q000601:surgery*; D061208:Pulsed Radiofrequency Treatment / Q000379:methods*; D055502:Secondary Prevention; D016896:Treatment Outcome; D018084:Ultrasonography, Interventional / Q000009:adverse effects / Q000379:methods
chemical_list: D000889:Anti-Arrhythmia Agents