February 8th, 2012
Two Different Perspectives on the CABG Versus PCI Message in ASCERT
At the recent meeting of the Society of Thoracic Surgeons (STS), Fred Edwards presented the high-risk subset of ASCERT (ACCF-STS Database Collaboration on the Comparative Effectiveness of Revascularization Strategies). CardioExchange Interventional Cardiology moderators Rick Lange and David Hillis posed the following questions to Edwards and Christopher White, the president of the Society for Cardiovascular Angiography and Interventions (SCAI).
Rick Lange and David Hillis (RL and DH): Given the limits of observational studies, are you concerned about how this study will be interpreted?
Edwards: All studies, whether observational or randomized, have limitations. This study is no exception. Since ASCERT is an observational study, well-accepted statistical analyses are used to minimize selection bias and to balance the clinical characteristics of the two treatment groups. An exhaustive statistical approach that included numerous analytic techniques was used to achieve excellent balance between the two groups so we could have an apples-to-apples comparison of survival.
We should be careful to interpret the results specifically for the high-risk subgroups presented. It would be a misinterpretation to conclude that the same results would necessarily be expected in other subgroups or in patients less than 65 years of age. With those caveats in mind, though, we can safely say that ASCERT confirmed a distinct survival advantage in surgical patients as compared to PCI patients having very similar clinical characteristics. As seen in numerous other observational studies and some randomized trials, the survival advantage for surgery increases with time.
We should mention that the overall results and the results of other important subgroups will be presented in about two months at the ACC Annual Meeting.
White: ASCERT was NOT meant or designed to directly compare “outcomes” for PCI vs CABG because of major biases in how the data were collected (i.e., registry and CMS administrative databases). The major limitation is that patients who were initially referred for CABG, but were refused surgery due to their concurrent illnesses or comorbidities, were often treated with PCI for symptomatic relief. Because these patients were much sicker than patients offered CABG, their mortality rate (during follow-up) was higher. This does not mean they died from their PCI; they probably died from their concurrent illnesses. ASCERT is weakened because patients were not randomized, and there was no intention-to-treat analysis as required by Level 1 evidence.
Well-balanced, well-done, prospective randomized trials comparing CABG to PCI — like SYNTAX — offer a much better opportunity to compare PCI and CABG. SYNTAX was an apples-to-apples comparison; ASCERT is an apples-to-oranges comparison.
What ASCERT tells us is that in our current practice, based on trials like SYNTAX, cardiologists are selecting appropriate patients for CABG, and this is resulting in good clinical outcomes for “real-world” patients.
RL and DH: Should this study change our practice? If so, how?
Edwards: The results of this study should encourage physicians to recognize the growing body of evidence showing that long-term survival is better with CABG than with PCI in most patient subsets. This survival advantage is becoming more evident each year. These ASCERT findings represent the world’s largest observational or “real world” CABG vs PCI study in high-risk patients. As such, it should prompt some reassessment of optimal revascularization strategy, not only by surgeons and cardiologists, but by primary care physicians as well.
I do not think ASCERT findings indicate that all high-risk patients should now be referred for CABG. The choice of revascularization is not dictated solely by long-term survival. There is more to it than that. Patient preference and quality of life expectations, for example, should be considered as well.
White: Absolutely not. ASCERT shows that the current selection process for CABG and PCI is yielding excellent results. If the process were changed — for example, if higher-risk patients received CABG — the outcomes of surgery would very likely worsen.
RL and DH: What should we tell our patients who are trying to decide between CABG and PCI and are aware of the results of this study?
Edwards: Some patients may conclude that the message of ASCERT is “surgery works better than stents.” We would do well to advise them that there is good evidence that long-term survival is better with surgery, but we also should note that there is an approximately 2% rate of in-hospital mortality with CABG compared with 1% with PCI. Complication rates, recovery time, and re-intervention rates should also be a central part of the conversation.
In most cases, surgeons should tell patients they need to also consult with a cardiologist. Likewise, cardiologists should refer patients for surgical consultation. In an ideal world, patients, surgeons, cardiologists and primary care physicians would all be talking to each other. The concept of a “heart team” of cardiologists and surgeons is a central part of the joint recommendations by STS and ACC on transcatheter valve replacement, and we believe that all coronary patients would benefit from a similar heart team approach. In fact, the newest guidelines published jointly by the ACC, AHA, and STS recommend a “heart team” approach for patients with complex coronary disease, so that patients have an opportunity to speak with both a surgeon and an interventionalist.
The highest priority for all of us in the medical profession is the patient — not our specialty, not our revenue, not our business model — just the patient. We must unwaveringly focus all our efforts on simply finding the best treatment for both the short-term and the long-term welfare of each of our patients.
White: Patients should understand that with clinical trials such as SYNTAX and FAME, their cardiologists have good comparative data on which to base their recommendation for medical therapy or revascularization (CABG or PCI). The ASCERT data suggest that cardiologists are properly selecting patients for CABG and PCI given the excellent real-world outcomes.