The abstract submission site for the 32nd Annual Meeting & Workshops opened July 20, 2009 and closes October 26, 2009 4 pm Eastern.
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.
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
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.
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