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Abstract Deadlines
The abstract submission site for the 32nd Annual Meeting & Workshops opened July 20, 2009 and closes October 26, 2009 4 pm Eastern.
Please visit SCA's Events page for details.
Pro/Con
All Cardiothoracic Anesthesiology Fellowships Should Be ACGME Accredited
Literature Reviews
Effects of Anesthetic Induction in Patients with Diastolic Dysfunction
Nitrous oxide and perioperative cardiac morbidity (ENIGMA-II) Trial: rationale and design
Can local application of Tranexamic acid reduce post-coronary bypass surgery?
Foundation Update
The Society of Cardiovascular Anesthesiologists (SCA) publishes the SCA Bulletin bimonthly. The information presented in the SCA Bulletin has been obtained by the editors. Validity of opinions presented, drug dosages, accuracy and completeness of content are not guaranteed by SCA.
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Percutaneous Coronary Intervention versus Coronary-Artery Bypass Grafting for Severe Coronary Artery Disease
Serruys PW, Morice MC, Kappetein P et al. for the SYNTAX investigators
New England Journal of Medicine 2009; 360: 961-72
Reviewers
Mona S. Kulkarni, MD, CA-3
Philip E. Greilich, MD, FAHA
University of Texas Southwestern Medical Center
Dallas, TX
Background
Percutaneous coronary interventions (PCI) such as stent placement are considered to be an effective treatment option for patients with less severe coronary artery disease (CAD). The superiority of drug-eluting stents (DES) in reducing the incidence of restenosis, as compared to bare metal stents (BMS), has led investigators to ask whether PCI with DES is equally effective as coronary artery bypass grafting (CABG) in patients with severe, multivessel CAD.
Methods
Eighty-five centers in Europe and the United States randomly assigned 1,800 patients with untreated, three vessel (or equivalent) CAD, to either CABG or PCI with DES (Taxus Express paclitaxil-eluting, Boston Scientific). A “heart team” (interventional cardiologist and cardiac surgeon) from each site evaluated eligible patients to determine if they were suitable to undergo either procedure. Only one treatment option (PCI or CABG) was deemed suitable in 1,275 patients (29%) who were enrolled in a nested registry for CABG-ineligible (198) and PCI-ineligible (1,075) subjects. The trial was sponsored by Boston Scientific.
The primary clinical end point was a composite of major adverse cardiac and cerebrovascular events (i.e. death from any cause, stroke, MI, repeat revascularization) throughout a 12 month period after randomization. Secondary outcomes included the individual rates of death, stroke, MI, and repeat revascularization. A SYNTAX score (EuroIntervention 2005;1:219-27) was calculated for each subject and divided into terciles (low £22, intermediate 23 to 32, high ³34) with higher scores corresponding to more complex CAD. The interaction between SYNTAX score and treatment group was then determined using the primary clinical outcome.
Results
The data were collected between March 2005 and April 2007. Data were analyzed in 1,740 patients who underwent CABG (849) or PCI (861). Baseline characteristics were similar in each group with the exception of a higher incidence of hypertension (>130/85mmHg) in the PCI group, and current smokers and dyslipidemia in the CABG group. More than 20% of the patients were deemed high risk by a euroSCORE value of 6 or more in both groups. Overall, four or more clinically significant (>70% stenosis) coronary lesions were treated in each patient. The SYNTAX score did not differ (p=0.19) between those undergoing CABG (29.1) and PCI (28.4). The average time to intervention was 7d for PCI and 17d for CABG. No significant (p=0.13) differences were found in pre-procedural event rates (0.3% PCI vs 0.9%, CABG).
Clinical Outcomes
At 12 months, the incidence of major adverse cardiac or cerebrovascular events (MACCE) was lower in the CABG group (12.4%) compared to the PCI group (17.8%, p=0.002). Thus, the absolute difference in MACCE was 5.5 percentage points with an upper 95% confidence interval of 8.3%. Secondary analysis revealed no differences in the rate of individual rates of death or MI between groups. Stroke was more likely to occur with CABG (2.2% vs 0.6%; p=0.003, compared to PCI). Repeat revascularization was more likely to occur with PCI (13.5% vs 5.9%; p<0.001 compared to CABG). The incidence of MACCE did not differ between those with low, intermediate and high SYNTAX scores in the CABG group, yet did so in those undergoing PCI with a high (23.4%) compared to a low (13.6%, p=0.002) or intermediate (16.7%, p=0.04) score.
Comments
The ratio of patients undergoing PCI to CABG for coronary revascularization remains about 4:1 despite mounting evidence (COURAGE, BARI-2D, etc) that PCI offers no survival advantage over optimal medical treatment or CABG in patients with multivessel CAD. The SYNTAX trial is the first, large, randomized controlled trial to demonstrate that PCI with DES is inferior to CABG in patients with severe, multivessel CAD. The appropriateness of CABG (“appropriate”) vs PCI (“uncertain”) in patients with three vessel CAD has been recently affirmed in an evidenced-based document written by a panel of experts that represented all relevant societies and included four cardiologists and four cardiac surgeons (Circulation 2009;119:1330-52).
The SYNTAX trial provides several additional insights worthy of further consideration. In the accompanying editorial, Drs. Lange and Hillis (NEJM 2009; 360: 24-26) opine that the protocol’s requirement of having a “heart team” (interventional cardiologist and cardiac surgeon) review each patient’s case prior to any intervention should be translated into widespread clinical practice. Although this would require a significant change in the “process of care” (e.g. diagnosis and intervention not at the same time), a growing body of evidence suggests this will likely represent a “best practice approach” in the future (J Thorac Cardiovasc Surg 2009;137:1050-3).
The SYNTAX trial’s conclusion that CABG remains the standard of care for patients with multivessel disease is based on a significant reduction in death, stroke, MI or repeat revascularization compared to PCI with DES (p=0.002). The use of a composite clinical endpoint, however, is controversial as it gives “equal weight” to each of these adverse events. Critics point to the secondary analysis that found no significant differences in the incidence of death between groups (3.5% for CABG vs 4.4% for PCI) and further argue that an absolute increase of 7.6 percentage points in rate of repeat revascularization in the PCI with DES is not equivalent to an absolute increase of 1.6 percentage points in stroke rate in those undergoing CABG. Although most would agree that survival should be the final arbiter, this trial did not have the statistical power (number of subjects, long-term follow-up) to do so. The survival trend at 12 months favoring CABG (hazard ratio 1.24) in this trial overlaps those found in several large, observational trials (HR 1.23 to 1.40). These hazard ratios increased to 1.44 to 2.30 with 3- to 5-year follow-up and indicate the need to stay tuned to the ongoing follow-up planned for this trial.
The high rate of symptom-driven, repeat revascularization in the PCI group (13.5% vs 5.9%; p<0.001 compared to CABG) had the greatest influence on the study’s primary clinical endpoint. The impact of a high SYNTAX score on MACCE in the PCI group suggests that the rate of repeat revascularization may be lowered if PCI were avoided in this high risk subgroup. In fact, the accompanying editorial suggests that the SYNTAX score should be used for risk stratification and that those with high SYNTAX scores should not be offered PCI as an option, unless the risk of surgery is clearly unacceptable. Many cardiologists have already adopted more simplified methods for identifying high risk patients such as those with diffusely diseased left anterior descending arteries who would benefit by grafting to the left internal thoracic artery.
The 1.6% absolute increase in stroke risk in patients undergoing CABG (compared to PCI) in this study and 0.6% absolute increase in a recently published meta-analysis (Ann Intern Med 2007; 147:703-16) is alarming to those considering surgical revascularization. The use of a “stroke score” to stratify risk in a manner analogous to the SYNTAX score may be the best way to address this concern. Stroke risk scoring systems designed by the Northern New England Cardiovascular Disease Study Group (Ann Thorac Surg 2003;76:436-43) and the McSPI group (Circ 1996;94:II74-80) have both been used to identified those at higher (>1%) risk of perioperative stroke or fatal cerebrovascular events (J Thorac Cardiovasc Surg 2006;131:734-5). Those at higher risk for stroke should have a treatment plan that considers revascularization with PCI, use of epiaortic scanning, OPCAB, a minimal or no (aorta) touch technique, a hybrid procedure and/or postoperative medical treatment that includes dual antiplatelet therapy. The authors point out that, compared to PCI, patients undergoing CABG were less likely to receive secondary prevention therapy such as aspirin (91% vs 84%), thienopyridine (71% vs 15%) and statin drugs (87% vs 75%). This may explain why 50% of the strokes in the CABG group occurred more than 30 days after the operation.
In conclusion, the SYNTAX trial represents another important addition to a growing literature that advocates for risk stratification and a process of care that allows patients to make an informed decision about their treatment plan. Although the study concludes that “CABG remains the standard of care” for severe CAD, patients will ultimately decide which short-term (repeat revascularization, stroke, quality of life) and long-term (death, etc) risks they are willing to accept in order to achieve durable coronary revascularization. As data emerges from this trial and others, anesthesiologists and surgeons need to make every effort possible to reduce the excess risk (stroke, etc) associated with surgical revascularization.