Advantages and challenges for noninvasive atrial fibrillation ablation.

PURPOSE Although catheter ablation is an effective therapy for atrial fibrillation (AF), risks remain and improved efficacy is desired. Stereotactic radiotherapy is a well-established therapy used to noninvasively treat malignancies with precision. We sought to evaluate stereotactic arrhythmia radioablation (STAR) as a therapeutic option for treating AF. METHODS AND RESULTS Three cancer patients with drug refractory AF were enrolled. Planning software using 3-D CT of the left atrium was used to design a desired ablation volume encompassing antral circumferential pulmonary vein isolation, roof and floor lines to create a "box" lesion set. After planning, patients were treated in the radioablation suite. STAR was able to deliver the intended radiation dose to the target in all 3 patients. No complications were observed over a follow-up period of 24 months. One patient with paroxysmal AF died from deterioration of cancer. The autopsy revealed evidence of fibroblasts and fibrogenesis in the region of atrial tissues targeted with radioablation. In one of these patients, left atrial posterior wall electrograms recorded from the esophagus before and 3 months after STAR indicated successful electrical isolation. CONCLUSIONS This is the first report of non-invasive radioablation of the left atrium with demonstration of successful electrical isolation. Although STAR may be safe and effective in delivering ablative energy to the left atrium, further evaluation is warranted regarding effectiveness.