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Comparing the Effectiveness of Coronary Artery Bypass Graft Surgery and Nonsurgical Catheter-Based Interventions for Coronary Artery Disease FREE

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The full report is titled “Comparative Effectiveness of Multivessel Coronary Bypass Surgery and Multivessel Percutaneous Coronary Intervention. A Cohort Study.” It is in the 21 May 2013 issue of Annals of Internal Medicine (volume 158, pages 727-734). The authors are M.A. Hlatky, D.B. Boothroyd, L. Baker, D.S. Kazi, M.D. Solomon, T.I. Chang, D. Shilane, and A.S. Go.

This article was published at www.annals.org on 23 April 2013.

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Ann Intern Med. 2013;158(10):I-24. doi:10.7326/0003-4819-158-10-201305210-00641
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What is the problem and what is known about it so far?

Coronary artery disease causes blockages of the blood vessels that supply the heart muscle and can lead to heart attacks, heart failure, and death. These blockages can be managed with heart surgery called coronary artery bypass grafting (CABG). They may also be managed with procedures performed with catheters inserted through the skin called percutaneous coronary interventions (PCIs). These include angioplasty or stenting in which a balloon or inserted coils dilate blocked areas. In clinical trials of highly selected patients randomly assigned to CABG or PCI, a small survival advantage has been seen with CABG. Whether this difference is also true among patients who might not have precisely the same characteristics of individuals who were enrolled in such trials (for example, because of other illnesses they might have) is not known.

Why did the researchers do this particular study?

To assess whether there is a difference between CABG and PCI when performed in real-world practice among patients not enrolled in clinical trials.

Who was studied?

105,156 patients who were enrolled in Medicare between 1992 and 2008 and had CABG or PCI.

How was the study done?

Researchers used electronic billing records to identify clinical characteristics of the patients, including diseases, such as diabetes, peripheral vascular disease (a narrowing of vessels other than those of the heart [such as in the leg]), or a history of heart failure or smoking. After “matching” patients to make groups that had similar proportions of patients with each of these and many other characteristics, they then compared the survival of those who had CABG with those who had PCI.

What did the researchers find?

Overall, survival was longer after CABG than after PCI. Although this difference was small (weeks to months), the difference in survival that might be predicted for any individual after CABG or PCI varied widely and was influenced by the presence or absence of certain medical factors. Patients with diabetes were predicted to have a particular survival advantage with CABG compared with PCI. Other factors that were associated with an advantage to CABG were a history of smoking, heart failure, or peripheral arterial disease. Conversely, patients lacking any of these factors would be predicted to have a slightly better chance of survival after PCI.

What were the limitations of the study?

This type of study cannot confidently determine whether CABG or PCI is the cause of improved or worsened outcomes when compared in the patients studied. The choice of CABG or PCI in the study patients was made considering many factors that the researchers could not assess. These factors might have important effects on how well a patient does after CABG or PCI. Such factors include problems with other kinds of surgery in the past, frailty, limited ability to walk or care for oneself, personal preferences, and many others.

What are the implications of the study?

The individual characteristics identified in this study are associated with whether a patient will have a greater survival benefit from CABG or PCI. Patients and physicians should discuss these and other factors when deciding the best plan of care.





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Functional SYNTAX score for reclassifying risk of patients with complex coronary artery disease for coronary bypass grafting
Posted on April 27, 2013
Gen-Min Lin
Hualien-Armed Forces General Hospital
Conflict of Interest: None Declared

To the Editor:

Current concept for coronary artery bypass grafting surgery (CABG) is indicated for patients with left main or triple-vessel coronary artery disease (CAD), diffuse lesions not amenable to percutaneous coronary intervention (PCI) and high-risk patients with severe left ventricular dysfunction or diabetes. Recently, the severity of coronary anatomy by the SYNTAX score in addition to the functional status was emphasized for patients with multi-vessel coronary artery disease undergoing CABG or PCI. In summary, the SYNTAX trials showed that CABG should remain the standard of care for patients with high or intermediate SYNTAX scores (23-32) in a 5 year follow-up. For patients with low SYNTAX scores (0-21), PCI was an acceptable alternative.1 Furthermore, patients with complex CAD who had more benefits from CABG could be evaluated by a combination of anatomical and clinical factors in SYNTAX score II system as well.2 These reports reclassified the “high-risk” patients with complex CAD by not only concomitant status with impaired ventricular function or diabetes but also systemically review for coronary severity and multi- risk factors estimation.

 In the community-based cohort study by Hlatky et al, the results expanded the evidence that those with complex CAD and risk factors of diabetes, tobacco use, heart failure, or peripheral arterial disease were in great favor of CABG.3 As is known, these factors were highly associated with severe coronary anatomy with high SYNTAX score, resulting in similar post-procedural prediction effectiveness. To further improve the SYNTAX score for reclassifying patients at high risk for PCI , the FAME (Fractional Flow Reserve Versus Angiography in Multivessel Evaluation) study demonstrated that the functional SYNTAX score (FSS) by only incorporating ischemia-producing lesions as determined by fractional flow reserve (FFR) decreased the number of higher-risk patients (32%) and better discriminates risk for the major cardiac adverse events in patients with multi-vessel CAD undergoing PCI.4

Obviously, near half of the FAME cohort with high SYNTAX score (mean: 21.7) were classified to the group with intermediate SYNTAX score (23-32) in the SYNTAX registry. In addition, the net reclassification rate from high to medium or low SYNTAX score was estimated to 38% by FSS in the FAME study. Accordingly, FSS may be more sensitive to select patients with intermediate SYNTAX score preferably to receive PCI or CABG. In our opinion, a cohort study is required to see patients with intermediate FSS and coexisting risk factors to follow up the subsequent cardiac events by treatments.


1. Mohr FW, Morice MC, Kappetein AP, Feldman TE, Ståhle E, Colombo A, Mack MJ, Holmes DR, Morel MA, Dyck NV, Houle VM, Dawkins KD, Serruys PW. Coronary artery bypass graft surgery versus percutaneous coronary intervention in patients with three-vessel disease and left main coronary disease: 5-year follow-up of the randomised, clinical SYNTAX trial. Lancet 2013; 381: 629-638

2. Farooq V, van Klaveren D, Steyerberg EW, Meliga E, Vergouwe Y, Chieffo A, Kappetein AP, Colombo A, Holmes DR, Mack M, Feldman T, Morice MC, Ståhle E, Onuma Y, Morel MA, Garcia-Garcia HM, van Es GA, Dawkins KD, Mohr FW, Serruys PW. Anatomical and clinical characteristics to guide decision making between coronary artery bypass surgery and percutaneous coronary intervention for individual patients: development and validation of SYNTAX score II. Lancet 2013; 381: 639-650

3. Hlatky MA, Boothroyd DB, Baker L, Kazi DS, Solomon MD, Chang TI, Shilane D, Go AS. Comparative Effectiveness of Multivessel Coronary Bypass Surgery and Multivessel Percutaneous Coronary Intervention: A Cohort Study. Ann Intern Med. 2013 Apr 23. doi: 10.7326-0003-4819-158-10-201305210-00639. [Epub ahead of print]

4. Nam CW, Mangiacapra F, Entjes R, Chung IS, Sels JW, Tonino PA, De Bruyne B, Pijls NH, Fearon WF; FAME Study Investigators. Functional SYNTAX score for risk assessment in multivessel coronary artery disease. J Am Coll Cardiol. 2011;58: 1211-1218.

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