JAMA：心肌纤维化是扩张型心肌病患者发生心源性猝死的独立预测因素

扩张型心肌病（DCM）是临床上常见的原发性心肌病，其主要表现为无明显冠状动脉狭窄的情况下出现心室腔的扩大，该病的总体预后不佳，尽管经过积极药物治疗，5年生存率仍小于80%，主要死亡原因为收缩性心力衰竭和心源性猝死。近来年，随着植入式转复除颤器（ICD）的问世，许多DCM患者避免了SCD的发生，然而由于ICD的价格昂贵，多数患者无法承受经济压力，为提高性价比，对DCM患者进行危险分层，识别高危患者具有重要的临床意义。
既往多项临床研究表明，左室射血分数（LVEF）是DCM患者发生SCD的独立预测因子，因此目前ICD植入的适应症主要依据LVEF值，然而我们发现许多LVEF值>35%的患者发生了心脏性猝死，而许多LVEF<35%的患者却是SCD的低危人群。因此，仅依靠LVEF来判断患者发生SCD的风险是不够的，我们急需寻找另一些预测因素。
心肌纤维化在扩张型心肌病患者中较常见，近来来延迟钆增强心血管磁共振成像（LGE-CMR）可成功识别心肌纤维化，目前关于心肌纤维化是否为扩张型心肌病患者SCD的预测因素还不清楚，据此Gulati A等近来了JAMA上发表了一篇临床研究，旨在探讨心肌纤维化与DCM预后的关系。
该研究共入选472例扩张型心肌病患者，所有患者均进行LGE-CMR检查，后进行平均5.3年的随访，主要临床终点事件为全因死亡，次要终点事件为心血管死亡、心脏移植、ICD放电等。结果显示：共有142例患者存在心肌中层纤维化，其中38例患者死亡，死亡率为26.8%，而无纤维化的患者中有35例死亡，占10.6%。心肌纤维化组患者心律失常事件的发生率为29.6%，而无纤维化组患者为7.0%，具有显著统计学差异。多因素回归分析提示，心肌纤维化是全因死亡、心血管死亡及SCD发生的独立预测因素。
通过该项研究可得出以下结论：心肌纤维化是扩张型心肌病患者不良预后的独立预测因素，其对预后的预测价值独立于LVEF。

 与心肌病相关的拓展阅读：

• JAMA：增强心脏MR可改善扩张性心肌病风险评估水平
• EUR HEART J：NT-proBNP有效预测肥厚型心肌病患者预后
• HEART RHYTHM :致心律失常性心肌病患者或存在心肌信号传导紊乱
• Circulation：肥厚性心肌病遗传外显率调查
• 靶向心肌重构与损伤 推进心肌病防治
• JBC：DES基因触发心律失常性右心室心肌病
更多信息请点击：有关心肌病更多资讯

Association of Fibrosis With Mortality and Sudden Cardiac Death in Patients With Nonischemic Dilated Cardiomyopathy
Importance
Risk stratification of patients with nonischemic dilated cardiomyopathy is primarily based on left ventricular ejection fraction (LVEF). Superior prognostic factors may improve patient selection for implantable cardioverter-defibrillators (ICDs) and other management decisions.
Objective
To determine whether myocardial fibrosis (detected by late gadolinium enhancement cardiovascular magnetic resonance [LGE-CMR] imaging) is an independent and incremental predictor of mortality and sudden cardiac death (SCD) in dilated cardiomyopathy.
Design, Setting, and Patients
Prospective, longitudinal study of 472 patients with dilated cardiomyopathy referred to a UK center for CMR imaging between November 2000 and December 2008 after presence and extent of midwall replacement fibrosis were determined. Patients were followed up through December 2011.
Main Outcome Measures
Primary end point was all-cause mortality. Secondary end points included cardiovascular mortality or cardiac transplantation; an arrhythmic composite of SCD or aborted SCD (appropriate ICD shock, nonfatal ventricular fibrillation, or sustained ventricular tachycardia); and a composite of HF death, HF hospitalization, or cardiac transplantation.
Results
Among the 142 patients with midwall fibrosis, there were 38 deaths (26.8%) vs 35 deaths (10.6%) among the 330 patients without fibrosis (hazard ratio [HR], 2.96 [95% CI, 1.87-4.69]; absolute risk difference, 16.2% [95% CI, 8.2%-24.2%]; P < .001) during a median follow-up of 5.3 years (2557 patient-years of follow-up). The arrhythmic composite was reached by 42 patients with fibrosis (29.6%) and 23 patients without fibrosis (7.0%) (HR, 5.24 [95% CI, 3.15-8.72]; absolute risk difference, 22.6% [95% CI, 14.6%-30.6%]; P < .001). After adjustment for LVEF and other conventional prognostic factors, both the presence of fibrosis (HR, 2.43 [95% CI, 1.50-3.92]; P < .001) and the extent (HR, 1.11 [95% CI, 1.06-1.16]; P < .001) were independently and incrementally associated with all-cause mortality. Fibrosis was also independently associated with cardiovascular mortality or cardiac transplantation (by fibrosis presence: HR, 3.22 [95% CI, 1.95-5.31], P < .001; and by fibrosis extent: HR, 1.15 [95% CI, 1.10-1.20], P < .001), SCD or aborted SCD (by fibrosis presence: HR, 4.61 [95% CI, 2.75-7.74], P < .001; and by fibrosis extent: HR, 1.10 [95% CI, 1.05-1.16], P < .001), and the HF composite (by fibrosis presence: HR, 1.62 [95% CI, 1.00-2.61], P = .049; and by fibrosis extent: HR, 1.08 [95% CI, 1.04-1.13], P < .001). Addition of fibrosis to LVEF significantly improved risk reclassification for all-cause mortality and the SCD composite (net reclassification improvement: 0.26 [95% CI, 0.11-0.41]; P = .001 and 0.29 [95% CI, 0.11-0.48]; P = .002, respectively).
Conclusions and Relevance
Assessment of midwall fibrosis with LGE-CMR imaging provided independent prognostic information beyond LVEF in patients with nonischemic dilated cardiomyopathy. The role of LGE-CMR in the risk stratification of dilated cardiomyopathy requires further investigation.