Leung D Y, Grimm R A, Klein A L
Department of Cardiology, Cleveland Clinic Foundation, OH 44195, USA.
Prog Cardiovasc Dis. 1996 Jul-Aug;39(1):21-32. doi: 10.1016/s0033-0620(96)80038-7.
In patients with atrial fibrillation, electrical cardioversion is often performed to relieve symptoms, to improve left ventricular function, and to decrease thromboembolic risks. However, cardioversion of atrial tachyarrhythmias is associated with an increased embolic risk, with an event rate of up to 5.6%. The American College of Chest Physicians recommend 3 weeks of systemic anticoagulation before elective cardioversion and 4 weeks of systemic anticoagulation afterwards. Expulsion of preexisting left atrial (LA) thrombi with resumption of sinus rhythm has traditionally been considered the mechanism for this increased embolic risk associated with cardioversion. The advent of transesophageal echocardiography (TEE) has allowed accurate detection of LA thrombus. Moreover, recent studies using TEE have identified a state of atrial "stunning" immediately after cardioversion, which is considered a thrombogenic milieu in which new thrombus formation and increased or de novo appearance of LA spontaneous echocardiographic contrast have been observed. Furthermore, embolic events have been reported after cardioversion despite exclusion of preexisting LA thrombus by TEE. These studies strongly suggest an alternative mechanism for embolism after cardioversion, ie, atrial stunning with worsened atrial appendage function and enhanced thrombogenesis. Recent studies have shown the safety of a TEE-guided anticoagulation approach in which exclusion of preexisting LA thrombus by TEE enables early cardioversion without the need for the standard 3 weeks of systemic anticoagulation. The importance of maintaining therapeutic anticoagulation has been further emphasized. Although preliminary observational studies of TEE-guided cardioversion are encouraging, there has been no prospective, randomized trial comparing the two strategies of anticoagulation management. The Assessement of Cardioversion Utilizing Transesophageal Echocardiography (ACUTE) pilot study randomized 126 patients from 10 sites and showed the feasibility and safety of the larger scale study. A larger multicenter, prospective randomized trial is now underway and is expected to randomize a total of 3,000 patients. The results of the ACUTE study will definitively establish the safest and the most cost-effective way to manage anticoagulation for elective cardioversion.
在心房颤动患者中，常进行电复律以缓解症状、改善左心室功能并降低血栓栓塞风险。然而，房性快速心律失常的复律与栓塞风险增加相关，事件发生率高达5.6%。美国胸科医师学会建议在择期复律前进行3周的全身抗凝，复律后进行4周的全身抗凝。传统上认为，随着窦性心律恢复，原有左心房（LA）血栓的排出是复律相关栓塞风险增加的机制。经食管超声心动图（TEE）的出现使得能够准确检测LA血栓。此外，最近使用TEE的研究发现复律后立即存在心房“顿抑”状态，这被认为是一种血栓形成环境，在此环境中已观察到新血栓形成以及LA自发超声造影增强或重新出现。此外，尽管通过TEE排除了原有LA血栓，但仍有复律后发生栓塞事件的报道。这些研究强烈提示复律后栓塞的另一种机制，即心房顿抑伴心房附件功能恶化和血栓形成增强。最近的研究表明了TEE引导下抗凝方法的安全性，通过TEE排除原有LA血栓可实现早期复律，而无需标准的3周全身抗凝。维持治疗性抗凝的重要性得到了进一步强调。尽管关于TEE引导下复律的初步观察性研究令人鼓舞，但尚无前瞻性、随机试验比较两种抗凝管理策略。利用经食管超声心动图评估复律（ACUTE）试点研究将来自10个地点的126例患者随机分组，显示了大规模研究的可行性和安全性。一项更大规模的多中心、前瞻性随机试验正在进行中，预计将总共随机纳入3000例患者。ACUTE研究结果将最终确定择期复律抗凝管理的最安全和最具成本效益的方法。
