在缺血性心肌病患者中，室性心律失常（VA）电风暴（ES）导管消融已经显示出适度的长期疗效。Di Biase及同事比较了两种不同方法用于这类心律失常治疗的有效性：心内膜表面的有限消融或瘢痕内所有异常电位的心内膜和心外膜消融（瘢痕同质化）。平均随访25个月，与有限消融组相比，联合消融组VA复发率显著降低（19％ vs. 47％）。研究证实，在缺血性心肌病患者中，采用心内外膜瘢痕同质化消融显著升高无VAs的可能性。
J Am Coll Cardiol. 2012;60(2):132-141.
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瘢痕同质化：电风暴缺血性心肌病的导管消融治疗新方法
Scar Homogenization: A Novel Approach to Catheter Ablation in Patients With Ischemic Cardiomyopathy Presenting With Electrical Storm
Erik Wissner 1 and Karl-Heinz Kuck 2
1 Magnetic Navigation Laboratory， Department of Cardiology， Asklepios Klinik St. Georg， Lohmuehlenstrasse 5， 20099 Hamburg， Germany
2 Department of Cardiology， Asklepios Klinik St. Georg， Lohmuehlenstrasse 5， 20099 Hamburg， Germany
With the widespread use of implantable cardioverter defibrillators (ICDs) for the prevention of arrhythmogenic sudden cardiac death， an increasing number of patients with appropriate ICD shocks are referred to the electrophysiology laboratory for catheter ablation of ventricular tachycardia (VT). To date， the impact of catheter ablation on mortality is unknown. Two prospective， randomized trials have demonstrated that an ablative strategy is beneficial in patients with ischemic cardiomyopathy presenting with a first-time episode of VT， resulting in greater freedom from recurrent VT and appropriate ICD shocks. In a nonrandomized study by Carbucicchio et al.， 37% of patients undergoing VT ablation for electrical storm (≥ 3 VT episodes over a 24-hour period) experienced arrhythmia recurrence during a mean follow-up period of 22 months. Conventional mapping and ablation of VT is commonly aided by a 3-dimensional electroanatomical mapping system and the arrhythmogenic substrate is identified based on substrate， pace， activation， and entrainment mapping. In this context， Di Biase and colleagues report a novel approach to catheter ablation in patients with ischemic cardiomyopathy presenting with electrical storm. In this multicenter observational study， group 1 (N=49) underwent conventional mapping and ablation of VT as detailed above， while endo- and epicardial scar， homogenization， that is， ablation of all abnormal potentials within and around scar was attempted in group 2 (N=43). The acute procedural endpoint was noninducibility of any monomorphic VT with a cycle length ≥200 ms. Four (8%) patients in group 1 necessitated epicardial mapping and ablation， while all patients in group 2 underwent epicardial access and mapping， but only 14/43 (33%) patients were found to have delayed， fractionated， or low-voltage potentials requiring epicardial ablation. The acute procedural endpoint was achieved in all study patients; however， 22-month freedom from recurrent VT was significantly higher in group 2 than group 1 (81% versus 53%， log-rank P=0.006).
The high success rate following scar homogenization is noteworthy. But before this technique is widely adopted， the findings by Di Biase et al. need to be verified by others. To date there is a paucity of randomized data on the best mapping and ablation technique when targeting ischemic VT. Arguably， results may be less stellar in centers performing fewer VT ablation procedures. Furthermore， extensive ablation during the initial procedure as required for scar homogenization may prevent proper localization of the arrhythmogenic substrate if VT recurs. All patients in group 2 underwent endo- and epicardial mapping but only a third of patients eventually required epicardial ablation. Although no complications related to epicardial access were reported， an epicardial approach may result in severe adverse events even in highly experienced centers， including inadvertent liver or bowel puncture or procedural death. Since the study by Di Biase et al. demonstrated no difference in long-term outcome between patients undergoing scar homogenization using a combined endo- and epicardial approach or endocardial ablation alone， epicardial access should probably be restricted to a select patient population. There is evidence that only a small proportion of patients with ischemic VT will benefit from epicardial mapping and ablation. The pathophysiologic process during ischemic injury may in part explain this finding， since at time of myocardial infarction， the wavefront of necrosis spreads from the subendocardial to the epicardial layer. Amongst 70 patients with previous myocardial infarction referred for catheter ablation of VT， merely 15% of patients with posteroinferior myocardial infarction required epicardial ablation， while all patients with anterior myocardial infarction were successfully treated by endocardial ablation alone. A routine epicardial approach， in particular if no abnormal substrate is found during mapping， may render patients ineligible for future epicardial instrumentation due to formation of pericardial adhesions. This problem may be more pronounced in patients undergoing extensive scar homogenization within the epicardial space during the initial procedure or in patients with prior coronary bypass grafting.In summary， scar homogenization represents a novel approach to VT ablation; however， further evidence needs to be accrued to assess its true value. The routine use of an epicardial approach in patients with ischemic cardiomyopathy needs to be critically assessed in future studies in light of the small proportion of patients in need of epicardial ablation and its potential for serious complications.
随着用于预防心律失常性心脏猝死的埋藏式心脏复律除颤器（ICD）的广泛应用，经ICD治疗后发生轻度休克的患者数量逐渐增多，这一现象与导管消融术后室性心律失常（VA）电风暴（ES）有关。迄今为止，导管消融术对死亡率的影响尚未明确。
Di Biase及其同事报道了一种电风暴缺血性心肌病的导管消融治疗新方法。在这项多中心观察性研究中，第1组患者（n=49例）接受常规的室性心动过速（VT）标测和消融术；而第2组患者（n=43例）则接受心内膜和心外膜消融（?瘢痕同质化），即对所有瘢痕内及周围的异常电位进行消融。两组的主要终点均是非诱导性、周期≥200 ms的单形性VT。第1组中4例（8%）患者必须接受心外膜标测和消融，而第2组仅2例患者需经心外膜标测，且仅14例（33％）患者因传导延迟、电位破碎或低电压而需接受心外膜消融。所有患者均达到主要终点；但第2组患者22个月内VT的复发率显著低于第1组（81% vs. 53%，，P=0.006）。
Di Biase等研究表明，采用心膜内和心外膜联合消融或单独心内膜消融进行瘢痕同质化治疗的两组患者的长期结果并无显著差异，心外膜消融术治疗应局限一个特定的患者群。仅小部缺血性VT患者受益于心外膜标测和消融术。缺血性损伤的病理生理过程可部分解释这一发现，因为心肌梗死时，坏死面从心内膜往心外膜层扩散。
总之，瘢痕同质化代表了一种新的VT消融治疗技术，但此技术的真正价值仍需进一步的证据来评估。鉴于需要接受心外膜消融治疗的患者比例较小，及其潜在的严重并发症，建议未来开展研究，审慎评估常规心外膜穿刺消融术治疗缺血性心肌病患者的疗效。