射频消融术可治愈大部分房颤

旧金山——圣路易斯巴恩斯犹太医院心胸外科医生Ralph J. Damiano Jr.博士在美国胸外科协会(AATS)年会上报告称，一项前瞻性多中心研究表明，心脏手术期间行射频消融术治疗持续性房颤(AF)成功率在不同医疗机构间存在显著差异，提示应进一步培训规范射频消融术治疗，以提高治愈率。


Ralph J. Damiano Jr.博士
 
在CURE AF(同期应用射频能量治疗AF)研究中，研究者分析了2007年5月~2011年7月在15家医学中心接受灌注式单极或双极射频消融术治疗的150例持续性或永久性AF患者的治疗情况。研究方案包括应用Cox Maze IV术。患者平均年龄71岁，56%为男性，大多属于纽约心脏协会(NYHA)分级Ⅱ或Ⅲ级心衰患者。AF平均持续时间为64个月。大多数患者(75%)为长期持续性AF，22%为持续性AF，3%为阵发性AF。

结果显示，66%的患者达到了随访6~9个月期间无AF的主要疗效终点指标，53%的患者在随访期间没有服用抗心律失常药物。Damiano博士称，大部分持续性AF患者接受灌注式射频消融Cox Maze IV术后恢复窦性节律，且并发症发生率较低。此外，不同类型AF患者有效性结果未见统计学差异。

该研究的主要安全指标为30天主要心脏复合不良事件发生率。结果该比率为6.6%，但无1例与器械有关。无患者出现肺静脉栓塞，手术死亡率为4%。

研究者称，有意义的射频消融术成功(定义为无AF)预测指标包括AF持续时间较短、左房内径较小以及同期心脏手术较少。例如，总射频消融时间<6分钟成功率为50%，消融时间≥12分钟则成功率提高至80%。左房内径是多变量分析后唯一仍具有意义的成功预测指标。研究者发现，左房内径为3.0~4.5 cm的患者69%无AF，而左房内径>6 cm的患者仅36%无AF。患者平均左房内径为5.2 cm。

不同研究中心的成功率存在显著差异。1家中心成功率为33%，而另外3家则高达100%。Niv Add博士评论认为，中心差异或许是该研究的最重要发现。研究者指出，不同外科医生的消融时间差异较大，手术过程并非完全一致，提示需要开展更为有效的手术和设备使用培训。

共有80%的患者患有二尖瓣疾病，58%患有心衰，52%患有三尖瓣疾病。最常见手术为单瓣修复术伴或未伴冠脉旁路移植术(CABG)，占53%；30%为双瓣修复术伴或未伴CABG，15%为CABG，1%为三瓣修复术伴或未伴CABG，其他手术占1%。

应用传导阻滞测定术中肺静脉隔离，81%的患者隔离成功。射频消融术采用美敦力公司Cardioblate单极或双极设备。鉴于该设备用于上述适应证的申请尚未获得美国FDA批准，因此属于超适应证使用。

Damiano博士担任美敦力公司顾问，该公司资助了上述研究。

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By: DAMIAN MCNAMARA, Cardiology News Digital Network

SAN FRANCISCO – Considerable variation by institution suggests that additional training is needed to standardize radiofrequency ablation of persistent atrial fibrillation in patients undergoing concomitant cardiac surgery, according to a prospective, multicenter study.

"As surgeons we need to take the ‘a fib’ part of the procedure more seriously. There can be a high cure rate," Dr. Ralph J. Damiano Jr. said at the annual meeting of the American Association for Thoracic Surgery.
 
He and his associates studied 150 consecutive patients with persistent or permanent atrial fibrillation (AF) undergoing irrigated unipolar or bipolar radiofrequency treatment at 15 centers between May 2007 and July 2011. The study protocol included use of the Cox Maze IV lesion set.

Freedom from AF at 6-9 months’ follow-up was a primary efficacy end point of the CURE AF (Concomitant Utilization of Radiofrequency Energy for Atrial Fibrillation) trial; this outcome was achieved by 66% of patients. Just more than half of patients, 53%, were not taking antiarrhythmia medications at this follow-up time, another measure of efficacy.

"The Cox Maze IV procedure performed with irrigated radiofrequency ablation in patients with persistent atrial fibrillation restored the majority of patients to sinus rhythm with a low complication rate," Dr. Damiano said.

There was no statistical difference in efficacy outcomes by AF type. Most of the participants, 75%, had long-standing persistent atrial fibrillation, 22% had persistent AF, and 3% had paroxysmal AF.

The mean patient age was 71 years, 56% were men, and the majority had New York Heart Association (NYHA) class II or III heart failure. The mean duration of AF was 64 months.

The primary safety measure in the study was the major cardiac composite adverse event rate within 30 days. A total 6.6% of participants experienced such an event, although none were device related, Dr. Damiano said. There were no cases of pulmonary vein stenosis, he added. Operative mortality was 4%.

Significant predictors of success, defined as freedom from AF, included shorter duration of the persistent or permanent atrial fibrillation, smaller left atrial diameter, and fewer concomitant cardiac procedures, said Dr. Damiano, a cardiothoracic surgeon at Barnes Jewish Hospital in St. Louis.

As an example, the success rate was 50% when total radiofrequency ablation time was less than 6 minutes. By comparison, success grew to 80% with ablation times of 12 minutes or longer.

Left atrial diameter was the only significant predictor of success that remained on a multivariate analysis. Dr. Damiano and his colleagues found that 69% of patients with a left atrial diameter of 3.0-4.5 cm were free from AF, compared with 36% who had a diameter larger than 6 cm. The overall mean left atrial diameter was 5.2 cm.

There were significant differences in achievement of success among different study centers, including a 33% success rate at one site versus 100% at three other sites, Dr. Damiano said.

"The variability between centers is probably one of the most important findings in this study," study discussant Dr. Niv Add said. He asked: "How would you see moving forward with training and credentialing of surgeons?" Dr. Add is chief of cardiac surgery at Inova Fairfax Hospital, Falls Church, Va.

"We were supposed to perform the exact same procedure in the same way," Dr. Damiano replied. "The surgeons all agreed on the lesion set [but] it’s hard to quantify experience. You can see a huge variation in ablation time, so clearly we were not all performing the same procedure. This variability suggests a need for more effective procedural and device training."

A total 80% of patients had concomitant mitral disease; 58% had heart failure; and 52% had tricuspid disease.

The most common surgical procedure was single valve with or without coronary artery bypass grafting (CABG) in 53%. Double-valve surgery with or without CABG was performed in 30% of patients; CABG in 15%; triple-valve with or without CABG in 1%; and other surgery in 1%.

Intraoperative pulmonary vein isolation was measured using exit block and was achieved for 81% of patients. Radiofrequency ablation was performed using Medtronic’s Cardioblate unipolar or bipolar device. As the device is not yet cleared by the Food and Drug Administration for this indication, such use is considered off label.

Dr. Damiano is a consultant for Medtronic. Medtronic sponsored the trial.