鉴别下壁STEMI与心包炎的新策略

丹佛——在美国急诊医师协会(ACEP)2012年会上，明尼阿波利斯Hennepin县医疗中心的Johanna E. Bischof博士报告称，对于ECG示下壁导联ST段明显抬高的患者，aVL导联ST段下降提示下壁ST段抬高型心肌梗死(STEMI)而非心包炎或早期再极化的敏感性和特异性都很高。

Johanna E. Bischof博士

只要心脏传导正常不伴左束支传导阻滞、WPW综合征、起搏节律或左室肥大，许多不会危及生命的心脏问题都可能引起下壁导联ST段抬高。Bischof博士及其同事针对容易与下壁STEMI混淆的2种心脏问题——心包炎和早期再极化，评估了ECG示aVL导联ST段下降的临床意义。

这项回顾性研究纳入了156例Hennepin县医疗中心收治的确诊为下壁STEMI的患者、39例≥2个下壁导联示ST段抬高至少1 mm的心包炎患者以及66例下壁导联示ST段抬高的早期再极化患者。早期再极化患者来自2000年芬兰健康调查，这次调查记录了将近11,000名无症状成年人的ECG。

在这156例确诊为下壁STEMI的患者中，155例的aVL导联ST段下降。而在下壁导联ST段抬高的心包炎或早期再极化患者中，没有1例存在这样的情况。

仅86%的下壁STEMI确诊患者符合传统的STEMI干预标准，也就是说其余14%的患者可能没有立即接受心导管术。如果采用新的aVL导联ST段下降的ECG标准，那么每名下壁STEMI患者都应该立即送往心导管室。

此外，如果根据下壁ST段抬高的表现来判断，那么心包炎组49%的患者都会被送往心导管室，但最终的血管造影结果却提示阴性。相反，如果采用基于aVL导联ST段下降临床意义的新的ECG判断标准，没有1例心包炎患者会被送往心导管室。

当Ⅲ导联的ST段抬高程度大于Ⅱ导联时，传统认为这提示下壁STEMI的可能性更大；而当Ⅱ导联的ST段抬高程度大于Ⅲ导联时，则往往认为这提示心包炎。然而，Bischof博士的研究显示，仅87%的确诊为下壁STEMI的患者其Ⅲ导联的ST段抬高程度大于Ⅱ导联。在心包炎组中，98%的患者Ⅱ导联的ST段抬高程度大于Ⅲ导联。在早期再极化组中，两种情况大约各占一半。

Bischof博士总结道，在这3种不同的Ⅱ、Ⅲ和(或)aVF导联示ST段抬高的患者人群中，aVL导联ST段下降至少0.25 mm提示下壁STEMI的敏感性为99%，特异性则达到了100%。“这比传统的ST段抬高干预标准更加敏感，其敏感性和特异性也高于比较Ⅲ导联和Ⅱ导联ST段抬高程度的判断方法。”

听取了报告的急诊科高级医师称Bischof博士的这项研究“很有价值”，并表示希望看到未来研究纳入更多的心包炎患者以确认如此之好的敏感性和特异性数据。一名医师评论道：“如果这一结果能得以进一步的证实然后运用到急诊实践中，那真的会让事情变得很简单。”

Bischof博士声明无相关经济利益冲突。

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By: BRUCE JANCIN, Cardiology News Digital Network

DENVER – The presence of any ST depression in the ECG lead aVL in a patient with significant ST segment elevation in inferior leads is highly sensitive and specific for inferior ST-elevation MI as opposed to pericarditis or early repolarization, Dr. Johanna E. Bischof reported at the annual meeting of the American College of Emergency Physicians.

In her retrospective study of three different patient populations with ST elevation in leads II, III, and/or aVF, the finding of at least 0.25 mm of ST depression in lead aVL had 99% sensitivity and 100% specificity for inferior STEMI.

"It’s more sensitive than traditional ST elevation intervention criteria, and more sensitive and specific than comparing the difference in ST elevation between leads III and II," said Dr. Bischof of Hennepin County Medical Center, Minneapolis.

Numerous non–life-threatening cardiac conditions can provoke ST elevation in the inferior leads in the presence of normal conduction with no left bundle branch block, Wolff-Parkinson-White syndrome, paced rhythm, or left ventricular hypertrophy. She and her coworkers evaluated the significance of any ST depression in aVL in two of these conditions that are often confused with inferior STEMI based upon the ECG: pericarditis and early repolarization.

Her retrospective study included 156 Hennepin County Medical Center patients with confirmed inferior STEMI, 39 patients with pericarditis and 1 mm or more of ST elevation in two or more inferior leads, and 66 Finns with early repolarization and ST elevation in inferior leads. The subjects with early repolarization came from the Finnish Health 2000 Survey, in which ECGs were recorded for nearly 11,000 asymptomatic adults.

Of the 156 patients with confirmed inferior STEMI, 155 had ST depression in aVL. Not one of the patients with ST elevation in inferior leads and pericarditis or early repolarization did.

Only 86% of patients with a true inferior STEMI met traditional intervention criteria for STEMI. That means 14% of them might not have gotten to the cardiac catheterization promptly. Using the novel ECG criterion of ST depression in aVL, everyone with an inferior STEMI would have been sent to the cath lab straight away.

Moreover, based upon the finding of ST elevation in inferior leads, 49% of patients in the pericarditis group would have been sent to the cath lab for what would have turned out to be a negative angiogram. With application of the new finding regarding the clinical significance of any ST depression in aVL, none of the patients with pericarditis would have gone to the cath lab, Dr. Bischof continued.

When the degree of ST elevation in lead III exceeds that in lead II, it has traditionally been thought to be more suggestive of inferior STEMI, whereas ST elevation in lead II that’s greater than in lead III is more often thought of as pericarditis. But in Dr. Bischof’s study, only 87% of patients with confirmed inferior STEMI had greater ST elevation in lead III than II. In the pericarditis group, 98% of patients had more ST elevation in II than III. And in subjects with early repolarization, it was roughly 50/50 as to which lead had greater ST elevation.

Senior emergency medicine physicians in the audience called Dr. Bischof’s study "fabulous," adding that they’d like to see the study expanded to include larger numbers of pericarditis patients just to be sure of those excellent sensitivity and specificity figures.

"Truly, if we could take this finding out and utilize it in the ED it would make things very easy for us," one physician commented.

Dr. Bischof reported having no financial conflicts.