颈动脉支架置入风险年龄切点或应降至65岁

美国密尔沃基——在美国中西部血管外科学会2012年会上，华盛顿大学医学院的血管外科专家Jeffrey Jim博士报告了一项引发争议的人群研究。该研究表明，与之前报告的CREST等关键性试验的结果相比，更年轻的Medicare参保患者在颈动脉支架置入术后也有出现不良结局的风险。

Jeffrey Jim博士

这项分析是基于2005~2009年收治的678,081例颈动脉血管成形和支架置入术(CAS)以及颈动脉内膜切除术(CEA)住院患者，均来自全美住院患者样本(NIS)的最新数据。NIS是医疗成本与效用项目开发的一个综合性住院患者数据库，大约覆盖了全美20%左右的医院。

在595,813例CEA病例中无症状患者所占的比例更高；而在82,268例CAS病例中男性、临床高风险、在教学医院接受治疗以及急诊/紧急入院的患者比例更高。CEA组和CAS组患者的平均年龄分别为71岁和70岁。两组均有3/4左右的患者加入了Medicare保险计划。

这项研究的主要复合终点包括死亡、卒中或心脏并发症。在整个患者队列中，CAS组和CEA组的复合终点发生率分别为6%和4.3%(P＜0.0001)。CAS组患者出现主要终点中每一种事件的风险都显著高于CEA组：死亡(1.1% vs. 0.5%)、卒中(2% vs. 1%)和心脏并发症(3.6% vs. 3.1%)。

主要终点的独立预测因子包括CAS、症状性狭窄以及临床高风险，其中临床高风险定义为患者年龄大于或等于80岁、或者患有肾功衰、重度慢性肺病、近期出现过心肌梗死、术前30天内接受过冠状动脉旁路移植术/心脏瓣膜手术、存在不稳定性心绞痛或者Ⅲ/Ⅳ级心衰。

在年龄小于65岁的患者亚组中，CAS组和CEA组的复合终点发生率分别为5.2%和3.6%；在年龄≥65岁的患者亚组中分别为6.3%和4.5%，这部分患者占整个队列的76%(P均＜0.0001)。

此外，在年龄≥65岁的无症状性患者中，CAS组和CEA组的主要终点发生率相似(4.1% vs. 3.8%；P=0.25)；但在年龄≥65岁的症状性患者中，CAS组的发生率显著高于CEA组(22.5% vs. 12.5%；P＜0.0001)，这是因为主要终点中所有3种事件的发生率都显著升高：死亡(5.1% vs. 2.2%)、卒中(12.5% vs. 7.6%)和心脏并发症(7.5% vs. 4.2%)。Jim博士表示：“这一结果与我们之前根据CREST试验所预期的有点不一样。”

在CREST试验(颈动脉血运重建内膜切除术与支架置入术对比试验)的导入期，80岁以上患者在CAS后出现院内死亡和卒中的风险更高，但出现心肌梗死的风险无明显增加(J. Vasc. Surg. 2004;40:1106-11)。CREST试验的后续分析发现，患者年龄与颈动脉支架植入效果之间存在相关性，年龄分界线在70岁左右(N. Engl. J. Med. 2010;363:11-23)。

从这项研究的结果来看，似乎还应该下调这一年龄分界线，与此同时Medicare与Medicaid服务中心也开始重新考虑在全国范围内覆盖颈动脉支架置入术的决定。Jim博士指出，接受支架置入术的患者其医疗成本也更高，不过他没有给出具体数据。

Jim博士说：“我们的研究结果表明，在处于Medicare医保年龄段的患者中，颈动脉血管成形和支架置入术与不良结局发生率和治疗费用增加相关，因此不支持在一般人群中广泛采用颈动脉支架置入术而非CEA。”
 

Jeffrey Jim博士(左)和Patrick Geraghty博士(右)

作为这场会议的主持人，美国圣路易斯巴恩斯-犹太医院的血管外科医生Patrick Geraghty博士说，两组患者在心肌梗死发生率上的差异“几乎与CREST试验的结果完全相反”。他还询问研究者是否对两组患者的心肌肌钙蛋白水平进行了同样的追踪。Jim博士回答称，由于这项分析采用的是NIS数据库，因此没有办法开展这样的追踪；而且也不排除某一家医院将肌钙蛋白水平0.15 ng/ml视为肌钙蛋白渗漏，而另一家医院将其编码为心肌梗死的可能性。此外，也无法从数据库中获取解剖信息和手术细节。

Jim博士和Geraghty博士声明无相关经济利益冲突。

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By: PATRICE WENDLING, Cardiology News Digital Network

MILWAUKEE – The risk for worse outcomes following carotid-artery stenting may extend to even younger Medicare-age patients than previously reported by such pivotal trials as CREST, a provocative population study suggests.

The rate of the composite primary end point of death, stroke, or cardiac complications was 5.2% for carotid angioplasty and stenting (CAS) and 3.6% for carotid endarterectomy (CEA) among patients younger than age 65 years, and was 6.3% vs. 4.5% among patients aged 65 years or older, who comprised 76% of the study cohort (both P values less than .0001).
 
Rates of the primary end point were similar between the carotid stenting and endarterectomy groups among asymptomatic patients aged 65 years or older (4.1% vs. 3.8%; P = .25), but were significantly higher in symptomatic patients age 65 years or older who received stenting (22.5% vs. 12.5%; P less than .0001).

This finding was driven by significantly higher rates of all three individual components of the primary end point: death (5.1% vs. 2.2%), stroke (12.5% vs. 7.6%), and cardiac complications (7.5% v s. 4.2%), "which is a little bit different than what we thought, compared with the CREST trial," lead author Dr. Jeffrey Jim said at the annual Midwestern Vascular Surgical Society meeting.

In the lead-in phase of CREST (Carotid Revascularization Endarterectomy vs. Stent Trial), octogenarians were found to be at higher risk of in-hospital death and stroke post CAS, but not myocardial infarction (J. Vasc. Surg. 2004;40:1106-11).

Subsequent CREST analyses have identified an interaction between age and carotid stenting efficacy, with the crossover at an age of approximately 70 years (N. Engl. J. Med. 2010;363:11-23).

The current results appear to move that threshold to an even younger age, just as the Centers for Medicare and Medicaid Services starts reconsidering the national coverage decision for carotid-artery stenting. Although he did not present the data, Dr. Jim noted that hospital costs also were higher for stenting patients.
 
"Our results show that carotid angioplasty and stenting was associated with a higher rate of adverse outcomes and increased charges among patients of Medicare age, and really don’t support the widespread use of carotid stenting over CEA in this general population," Dr. Jim said.

Session moderator Dr. Patrick Geraghty, a vascular surgeon with Barnes–Jewish Health in St. Louis, said the difference in MI rates between arms "basically turns the CREST findings on their head," and asked whether cardiac troponin levels were tracked equally in both arms.

Dr. Jim responded that such tracking wasn’t possible with the Nationwide Inpatient Sample (NIS) database used for the analysis, and that it’s unknown whether one hospital called a troponin level of 0.15 ng/mL a troponin leak, while another coded that as an MI. Anatomic information and operative details also were not available.

The analysis was based on 678,081 hospitalizations for CEA and CAS from 2005 to 2009, the latest available data in the NIS, a comprehensive, inpatient database developed as part of the Healthcare Cost and Utilization Project and designed to approximate a 20% sample of U.S. hospitals.

The 595,813 CEA patients were more likely to be asymptomatic, whereas the 82,268 CAS patients were more likely to be male, medically high risk, treated at a teaching hospital, and an emergent/urgent admission.

The average age was 71 years in the CEA group and 70 years in the CAS group. Three-fourths of both groups had Medicare insurance coverage.

In the entire study cohort, the composite primary end point occurred in 6% of the carotid stenting group and 4.3% of the endarterectomy group (P less than .0001), said Dr. Jim, a vascular specialist at Washington University School of Medicine, St. Louis.

Patients who underwent carotid stenting experienced significantly higher rates of each individual component of the primary end point: death (1.1% vs. 0.5%), stroke (2% vs. 1%) and cardiac complications (3.6% vs. 3.1%).

Independent predictors of the primary end point were CAS, symptomatic stenosis, and medical high risk, defined as a patient age 80 years or older, or a patient who had renal failure, severe chronic lung disease, recent MI, coronary bypass/valve surgery within 30 days, unstable angina, or class III/IV heart failure.

Dr. Jim and Dr. Geraghty reported having no relevant conflicts of interest.