Neurology Unit, Rabin Medical Center, Golda Campus, Petach Tikva and Tel Aviv University, Tel Aviv, Israel.
J Neural Transm (Vienna). 2011 Apr;118(4):637-40. doi: 10.1007/s00702-011-0590-0. Epub 2011 Feb 8.
Asymptomatic significant (≥50%) carotid stenosis (ASCS) is a frequent finding in the aging population. The prevalence of moderate stenosis (50-70%) increases from 3.6% for those <70 years to 9.3% in those ≥70 years. The (additional) prevalence of severe (70-99%) stenosis is 1.7%. The natural history of ASCS is quite benign. The overall risk of stroke is around 2% per year and within the group higher degrees of stenosis are associated with higher risks. Yet this stroke risk also includes "unrelated" strokes (i.e., lacunar and cardioembolic), and similarly, it is more of a marker for identifying high-risk group of patients at risk of cardiovascular morbidity and mortality (as revealed by many studies)! Carotid endarterectomy (CEA) has been evaluated in several studies; mainly ACAS and ACST. An overall modest benefit of about 1% risk reduction (per year) was found for CEA (with a peri-operative risk of <3%) versus medical treatment, over a 5-year period. Basically these two studies recruited similar patients with ≥60% stenosis based on carotid duplex. However, the similar favorable results differ: while ACAS (published in 1995) found the risk for ipsilateral stroke in the medical group to be 11% over a 5-year period, the 11.8% risk observed in ACST (published in 2004) was for any strokes--showing a better "natural history" for patients with ASCS in the recent study. This observation adds to other reports suggesting a better outcome for patients with ASCS in the recent years, probably because of better medical treatment, mainly due to the significant increase in the use of statins. The suggested guideline that results from the above-mentioned studies is that CEA should be considered in every patient with significant (≥60%?, ≥70%?) stenosis who has a life expectancy of more than 5 years (and is <75 years?). Taking this advice as such, would mean that we should screen for ASCS and operate on all appropriate candidates. This will result in a surge of CEA's! Such a recommendation is not in place, because the observed benefit of CEA by numbers needed to treat (NNT) per year to prevent any stroke is more than one hundred! (for symptomatic patients NNT is <10). This high-figure (i.e., low yield) results from failure of these studies to identify specific risk-factors (including the degree of stenosis within the wide range [60-99%] allowed in the studies) in patients with ASCS. Some studies are underway. Therefore, at present, it seems that for most patients, best (intensive) medical treatment is the best option. Alternately, they should join studies that will help to identify patients with the highest risk--those who will clearly benefit from carotid intervention.
无症状性显著（≥50%）颈动脉狭窄（ASCS）是老年人群中的常见发现。中度狭窄（50-70%）的患病率从<70 岁的 3.6%增加到≥70 岁的 9.3%。（额外的）重度狭窄（70-99%）的患病率为 1.7%。ASCS 的自然病史相当良性。每年发生中风的总体风险约为 2%，且在该组中，狭窄程度越高，风险越高。然而，这种中风风险还包括“无关”的中风（即腔隙性和心源性栓塞），同样，它更多地是一种标志物，可识别存在心血管发病率和死亡率风险的高危患者群体（正如许多研究所示！）！颈动脉内膜切除术（CEA）已在几项研究中进行了评估；主要是 ACAS 和 ACST。在 5 年期间，与药物治疗相比，CEA（围手术期风险<3%）发现每年约有 1%的风险降低（获益）。基本上，这两项研究根据颈动脉双功能超声都招募了≥60%狭窄的相似患者。然而，相似的有利结果却有所不同：尽管 ACAS（1995 年发表）发现药物组中同侧中风的风险在 5 年内为 11%，但在 2004 年发表的 ACST 中观察到的 11.8%风险是任何中风——表明最近研究中 ASCS 患者的“自然病史”更好。这一观察结果增加了其他报告，表明近年来 ASCS 患者的预后更好，可能是因为更好的药物治疗，主要是由于他汀类药物的使用显著增加。上述研究得出的建议准则是，对于预期寿命超过 5 年（<75 岁）且有≥60%（？，≥70%）狭窄的患者，应考虑进行 CEA！如果按照这一建议进行操作，那么就意味着我们应该筛查出所有合适的 ASCS 患者，并对其进行治疗。这将导致 CEA 的数量激增！但目前还没有这样的建议，因为每年通过治疗数量（NNT）预防任何中风的 CEA 获益都超过 100！（对于症状性患者，NNT<10）。这种高数字（即低收益）是因为这些研究未能在 ASCS 患者中确定特定的风险因素（包括研究允许的狭窄程度[60-99%]范围内的狭窄程度）。一些研究正在进行中。因此，目前，对于大多数患者而言，最好的（强化）药物治疗似乎是最佳选择。或者，他们应该参加研究，以帮助确定风险最高的患者——那些将从颈动脉介入治疗中明显获益的患者。
