持続性心房細動を止める(Presentation # 2188)
標準的な治療を行っているにもかかわらず長期の持続性心房細動（AF）を有する患者において、追加で左心耳（LAA）の電気的切除をすることで合併症を増加させることなくAFから解放される率が改善し得る、とのBELIEFスタディの結果が2015年ESC Congressホットラインセッションで発表された。研究者らは173人の患者を標準的な治療のみ（肺静脈隔離術および肺静脈外トリガーのアブレーション、88人）、または標準治療に加えLAAアブレーションを行う群（85人）にランダムに割り付けた。1年後の無再発率は標準治療群の28%に対し、LAAアブレーション追加群では56%であった（p=0.001）。両群とも再発した患者は次の施術としてLAAアブレーションを施行された。24か月後の平均施術件数は1.3件であり、累積成功率はLAAアブレーション群で76%、標準治療群では56%であった（p=0.003）。追跡期間中の、一過性脳虚血発作や脳卒中などの合併症率は両群間で差はなかったが、平均ラジオ波曝露時間はLAA群で長かった（93分対77分；p<0.001）。多変量解析では、LAAアブレーションを施行しないことはAF再発率が有意に高いことと関連があった（p=0.004）。
In patients with long-standing persistent atrial fibrillation (AF) despite standard treatment, additional electrical isolation of the left atrial appendage (LAA) can improve freedom from AF without increasing complications, results of the BELIEF study show.
The findings were presented in a Hot Line session at ESC Congress 2015.
"Empirical left atrial appendage isolation, along with the standard approach of pulmonary vein isolation (PVI) and ablation of extra-pulmonary triggers is superior to the standard approach alone in enhancing the long-term success rate of catheter ablation," reported investigator Luigi Di Biase, M.D., Ph.D., from Montefiore-Albert Einstein Center for Heart & Vascular Care, New York, USA and Texas Cardiac Arrhythmia Institute at St. David's Medical Center, Austin, Texas, USA.
"We first proposed in 2010 that the left atrial appendage was a relevant, under-reported trigger for AF, and now this trial confirms our findings," he added.
The study included 173 patents with "long-standing persistent" AF - defined as extending beyond one year.
Patients were randomly assigned to undergo standard treatment alone (PVI and ablation of extra-pulmonary triggers, n=88), or standard treatment plus the addition of LAA ablation (n=85).
For the primary endpoint of recurrence of AF at one year, 28% of standard treatment patients were recurrence-free compared to 56% of patients who had the additional LAA ablation (hazard ratio [HR] 1.92; p=0.001).
For patients who were not recurrence-free in either group, LAA isolation was performed in a second procedure.
At 24 months, after an average of 1.3 procedures, the cumulative success rate was 76% in the LAA ablation group and 56% in the standard treatment group. (HR 2.24; p= 0.003).
There was no difference in complication rates between groups at follow up, including transient ischemic attacks or strokes, however the mean radiofrequency time was longer in the LAA group (93 versus 77 minutes; p<0.001).
In multivariate analysis, no LAA ablation was associated with significantly higher recurrence of AF (HR 2.2; p = 0.004).
"It is logical to suggest that the LAA may initiate AF like the pulmonary veins because embryologically, the LAA grows out of the primordial LA, which is formed mainly by the adsorption of the primordial pulmonary veins and their branches," explained Dr. Di Biase.
"In fact, an earlier study conducted by our group showed that LAA firing was the source of AF in 27% of patients and, after LAA ablation, 93% of those patients were AF free at long term follow up."
The study was sponsored by Texas Cardiac Arrhythmia Research Foundation. Dr. Di Biase is a consultant for Biosense Webster, Stereotaxis and St Jude Medical and has received speaker honoraria/travel from Medtronic, Atricure, EPiEP, Boston Scientific and Biotronik.
