ABC | Volume 111, Nº4, Octuber 2018

Review Article Oliveira et al Risk-benefit of carotid revascularization Arq Bras Cardiol. 2018; 111(4):618-625 revascularization, were published in the beginning of the 1990's. 1-3 At that time, acetyl salicylic acid was the cornerstone of OMT. In NASCET study, two year stroke incidence was 26% in OMT group, compared to 9% in CEA group. 1 In 1995, primary prevention study ACAS 5 found a much lower (17.5%) five-year stroke incidence in its OMT group. In 2004, ACST 7 reported a further drop of stroke risk to 11.8% (2.4% annually), and by the time 10-year results were reported, in 2010, 17 there was an even greater reduction in OMT group (7.2% in the last five years of follow-up). ACST also showed that in those cases of stroke with untreated severe ipsilateral carotid stenosis, OMT reduced stroke risk by almost 70%, resulting in an annual stroke incidence of 0.7% in the last five years of follow-up 17 (Table 1). Stroke risk reduction was followed by a large reduction in myocardial infarction incidence during the same period, which is largely attributable to improvement of OMT and risk factor control. 18 A reduction of almost 30% in mortality from atherosclerotic coronary artery disease was reported in Brazil between 1990 and 2009. 19 Between 2003 to 2013, mortality rates due to coronary heart disease fell by 38% and the actual number of deaths decreased by 22.9% in the United States. 18 Studies with angiotensin-converting enzyme inhibitors (ACE inhibitors) have proved the benefit of this class of drugs on ventricular remodeling, showing also a reduction of 20% in cardiovascular events. 20,21 A meta-analysis of more than 30,000 patients demonstrated a protective effect of ACE inhibitors against ischemic events, even in patients without ventricular dysfunction. 22 Currently, several guidelines acknowledge the role of these drugs in preventing cardiovascular disease. 23-25 Nevertheless, routine use of statins is considered the greatest landmark in OMT. A meta-analysis of 26 RCTs (over 170,000 subjects), published in 2010, demonstrated the efficacy and safety of statins, as well as the correlation between the dose used and the protective effect. 26 Two randomized clinical trials reported in 2016 reinforced these findings. The  Effect of Statin Treatment on Modifying Plaque Composition (STABLE) study tested high-dose rosuvastatin through a follow-up with intravascular imaging. Besides stabilizing the atherosclerotic plaque, rosuvastatin could also induce some reversal of the atherosclerotic process. 27 A second study, Cholesterol Lowering in Intermediate‑Risk Persons without Cardiovascular Disease (HOPE 3), demonstrated that routine use of statin in primary prevention subjects with intermediate risk of cardiovascular diseases resulted in 24% reduction in outcomes, including stroke. 28 Risks and benefits of intervention Several international societies indicate carotid intervention in symptomatic patients, ipsilateral stroke or TIA within the previous 6 months, presenting at least 50% extracranial carotid stenosis. 15 Considering the great advances in clinical treatment in the last decades, the most important guidelines postulate that the intervention should only be performed when the periprocedural risks are smaller than 6%. 15,29-31 (Table 2) Table 2 – Management of patients with Symptomatic extracranial carotid stenosis 23-24 Carotid Stenosis Recommendations (Class and Evidence Level)* Periprocedural Risk to maintain clinical benefit < 50% OMT (IA) 50-59% CEA + OMT (IIaB) < 6% CAS + OMT (IIbB) 60-69% CEA + OMT (IIaB) < 6% CAS + OMT (IIbB) 70-99% CEA + OMT (IA) < 6% CAS + OMT (IIaB) Occlusion OMT (IA) OMT: Optimized medical therapy; CEA: Carotid endarterectomy, CAS: Carotid angioplasty and stenting. (Classes of Recommendation: I - The benefit is greater than the risk and the treatment/procedure should be performed or administered; IIa - The benefit is greater than the risk, but further studies are needed, so that it reasonable to perform procedure or administer treatment; IIb - the benefit is equal to or greater than the risk and treatment/procedure may be considered. Levels of Evidence: A - Data derived from multiple randomized clinical trials or meta-analyses; B - Data derived from a single randomized clinical trial or multiple non- randomized studies.) * For all patients: When procedure is indicated, CAS should only be performed if there is a high risk for CEA. Table 1 – Evolution of Clinical Treatment 23-24 Trial Publication Year Annual incidence of stroke in the clinically treated group ACAS 5 1995 3,5% ACST first 5 years 6 2004 2,4% ACST last 5 years 17 2010 1,4% 619