Introduction
By George W. Vetrovec, MD, MACC
Editorial Team Lead, Invasive Cardiovascular Angiography & Interventions collection on ACC.org
Richmond, VA

Guidelines, Clinical Statements, and Appropriate Use Criteria (AUC) remain useful and significant products to guide clinical patient management. Although often over-interpreted as "rigid" documents dictating practice, they in fact offer a very well-researched guide to help physicians in appropriate patient management. That said, no guideline can be entirely built on unequivocal evidence because the weighted significance of different trials as well as incompletely understood or studied issues all have to be interpreted by experts, ideally clearly noting the areas of controversy or limited scientific rigor.

Thus guideline documents are ultimately the combined wisdom of the expert writing group filtered by external reviewers. But the reality is that writing committees are limited in size, and many expert clinicians are not involved in the writing. Depending on the guideline, there is always some "second guessing" by the clinical community about various aspects of new guideline statements. The first AUC revascularization statement covered both stable and acute coronary syndromes (ACS) as a single document and created much controversy. The current approach has been to separate ACS from stable coronary disease for the purposes of an updated AUC statement.

In an attempt to offer selected clinicians not involved in the actual writing process a forum to comment on new guidelines, I invited a number of practice and academic "user" physicians to comment on the just released ACS AUC. These individuals were asked to provide 2-4 paragraphs with optimally 1-3 references to support their comments. This is not intended to support a "rant" against guideline statements but rather to elicit thoughtful comments on the positives, possible negatives, and areas with limited clarity in an attempt to have a useful dialogue for other practitioners.

This is an experiment. I appreciate the work of the contributors whose comments follow. I trust this will provide a useful discourse regarding the application of these guidelines to clinical practice.

Feedback is appreciated, and, if this commentary is deemed valuable, this collection will approach future guideline releases in a similar format.

AUC Are "User-Friendly" for Interventionalists
By H. Vernon Anderson, MD, FACC
McGovern Medical School at UT Health
Houston, TX

The AUC Task Force has just released the newest AUC document, this one on the subject of AUC for revascularization in patients with ACS.¹ This newest document is significant for several reasons. To begin with though, it is important to point out that it is focused exclusively on revascularization. It does not contain any material on important related topics such as dual antiplatelet therapy, choice of antithrombin agents, glycoprotein inhibitors, or arterial access by the radial or femoral approach. Clinicians must consult the full guidelines documents for information on those topics.^2,3 The new AUC document also does not distinguish much between revascularization methods in patients with ACS—percutaneous coronary intervention (PCI) or coronary artery bypass grafting (CABG)—recognizing that in clinical practice most patients receive PCI to the offending culprit lesion even if CABG is then performed afterward for coexisting multivessel disease.

The new AUC for ACS are more "user friendly" to interventional cardiologists and appear more closely aligned with actual clinical practices. There is clear recognition and support for early invasive strategies for patients with ACS. If multivessel disease is found at angiography, the new AUC acknowledge the reality of common clinical practice and bring into focus the recent studies and changes in guidelines that suggest potential benefit with PCI not only of the culprit lesion but also of nonculprit significant lesions either at the initial procedure or during the index hospitalization. Many of us have practiced this way for a long time, using the clinical judgement that is now receiving more support from these AUC. Performance of fractional flow reserve (FFR) on borderline nonculprit lesions to assess their suitability for PCI is rated as appropriate or reasonable, acknowledging another common practice. Of the 17 scenarios that are rated in this new document, 10 are rated "appropriate care," and 6 are rated "may be appropriate care." Only one is given the lowest rating of "rarely appropriate care." That one is scenario 13: revascularization of 1 or more nonculprit intermediate lesions in an asymptomatic patient with no additional testing after successful treatment of the culprit stenosis in a patient with ST-segment elevation myocardial infarction (STEMI).

The final important point is that this new document gives due approval to the role of patient preference in a shared decision-making process. The patient's desires and expectations along with the physician's knowledge, skill, and expertise are all respected as valid components of cardiovascular care in this setting. My conclusion from reading this document is that most interventionalists will be satisfied, if not somewhat relieved and pleased.

AUC: Helpful Tools in My Practice, but not Substitutes for Clinical Judgement
By Luis A. Guzman, MD, FACC, FSCAI
Medical College of Virginia at VCU Health
Richmond, VA

Rational utilization of health care resources is vital to provide the best possible care to our patients. The AUC represent an effort by several professional societies addressing the best alternative diagnostic tools and treatment for a specific patient clinical situation. It is important to emphasize the tremendous efforts and congratulate the writing committee and scoring panel for developing this document.

Before discussing the current update, it is important to highlight some limitations of the overall concept of creating AUC. Even though the document is based on the best available information and the results of a very detailed and thorough discussion of each specific scenario among experts in the field, it is difficult to incorporate every clinical situation that clinicians encounter on a daily basis. First, the information to make decisions in many clinical situations is either not available or derived from selected populations, with limits on extrapolating that practice to every clinical scenario. Second, multiple difficult-to-measure factors are also taken into consideration when a decision to proceed with a specific treatment in a specific case is made (e.g., social realities, personal preferences, and local availability of resources). Third, like every medical field, treatment of ACS is a dynamic and constantly evolving field. Due to scarce high-quality data, multiple clinical situations might not have a clear indication or even a contraindication for a diagnostic tool or treatment in today's practice. Therefore, an open mind and some degree of uncertainty should always be considered when applying these recommendations. In fact, this update clearly demonstrates how a practice that was considered contraindicated few years ago is now considered recommended with a "may be appropriate care" score (revascularization of a severe nonculprit artery in the context of STEMI). Fourth, even though cost-effectiveness is one of the goals of the AUC, there is very limited information about cost-effectiveness in most areas of interventional cardiology, with even less information for specific clinical situations. The AUC document should not be a substitute for sound clinical judgement; it should be considered a guideline to help physicians, hospitals, and payers address how to best serve our patients. It is also a useful tool for quality metrics and for determining treatment patterns among different groups or different providers. But it should not be used to determine the appropriateness of an individual case or to determine payment for an individual case.

The present update significantly clarifies revascularization indications to different ACS scenarios. A total of 17 clinical scenarios have been included and updated according to newly available information. A very important improvement in the current document is the incorporation of the clinical risk stratification scores into the decision-making process. Risk stratification has been proven in multiple prospective studies and large databases to clearly determine patient's risk of developing major "ischemic" clinical events. Despite this significant improvement, scores associated with bleeding risk and balancing both ischemic and bleeding risk are still not incorporated. Future documents might consider further exploring this concept. The other main improvement was the incorporation, based on the report of three randomized clinical trials (PRAMI [Preventive Angioplasty in Acute Myocardial Infarction], CvLPRIT [Complete versus Lesion-only Primary PCI Trial], and DANAMI-3-PRIMULTI [The Third Danish Study of Optimal Acute Treatment of Patients With STEMI: Primary PCI in Multivessel Disease]),^4-6 of the treatment of nonculprit coronary revascularization in STEMI patients during the same hospitalization. The three trials have clearly demonstrated the safety of performing additional revascularization whether in the same procedure or during the same hospitalization. Importantly, the current document changes the scenario from "rarely appropriate care" in prior documents⁷ to either "appropriate care" or "may be appropriate care" scenarios. Lastly, the document incorporates the physiologic assessment in the catheterization laboratory as a decision-making tool in the nonculprit artery in all patients with ACS. Evidence of residual ischemia based on physiology rather than visual estimation of lesion severity has been clearly demonstrated to be safe, effective, and cost-effective. This is an important step forward toward better care of the patient and a more appropriate utilization of revascularization resources.

This new document clarifies several clinical scenarios, and it is a step in the right direction toward a better tool for clinicians to best serve our patients. The current document clearly fits with my practice. However, due to the dynamic and constantly evolving nature of medicine, the initial goal of all AUC documents should be kept in mind, which is to "provide the framework for the assessment of practice patterns that will hopefully improve physician decision making;" this document is not to be considered a dogmatic document with payment, public reporting, or legal implications.

Reflections on the New AUC
By Jeffrey W. Moses, MD, FACC
Columbia University Medical Center
New York, NY

As with any update and revision of guidelines or AUC, progress had been made in the 2016 revision for ACS in incorporating new literature. But as questions are resolved in some areas, they frequently lead to the emergence of new issues; in that context, I found a few areas where my interpretations and practice may diverge from the conclusions of the AUC. In addition, there are areas where new questions have arisen because of the revision.

The change of category in scenario 3, (stable post-STEMI patient who is asymptomatic between 12 and 24 hours after myocardial infarction onset ) now been upgraded to "may be appropriate care" from "rarely appropriate care." This is an improvement over from previous document. My presumption was that the prior recommendation was based on an extrapolation of OAT (Occluded Artery Trial).⁸ However, OAT did not include patients in this 12- to 24-hour window and actually had a mean 8-day delay in time from myocardial infarction to PCI. So, it is reasonable to give the patients in this window the benefit of doubt because there are some inferential data and small studies indicating some potential benefit of PCI in this delayed group.^9,10 However, another question emerges regarding what to do after 24 hours. Obviously, when 12 hours or more was inappropriate, 24 hours was as well. In addition, when one also looks at the recommendation of scenario 9 (stable patient more than 24 hours after fibrinolysis) where PCI "may be appropriate care," it further confuses the issue. I think this is interesting because I assume the presumption in scenario 9 is that if you find that thrombolysis failed and the artery is occluded (a fairly common scenario after treatment of STEMI with fibrinolytic therapy) that PCI still may be appropriate. However, this is precisely the group of patients who were included in OAT and purportedly derive no benefit from PCI in terms death, myocardial infarction, and congestive heart failure.

My take on this is that one must think of OAT within the population that was actually recruited; if one scrutinizes this population, one sees that they were minimally symptomatic, that the vast majority had Q waves on their electrocardiograms (ECGs), or, if they had stress testing, that they had little or no ischemia. Thus, OAT comprised a quite rarified group. If one is confronted with a totally occluded vessel after 24 hours with absent Q waves on the ECG in the subtended region or there is still wall motion and collateralization, I think PCI is reasonable. We know from other studies of total occlusions that collateralization virtually never totally ameliorates ischemia, and the very presence of viable myocardium and an occluded vessel with collaterals is virtually a certain indication of inducible ischemia.¹¹ Obviously, if there are Q waves and/or regional akinesia in the occluded territory then further testing should be done to ascertain the possibility of recoverable myocardium. In the absence of evidence for viability, I would certainly not treat in that latter scenario. Parenthetically, even the minimally symptomatic OAT patients realized an early quality-of-life benefit from PCI.¹²

Another interesting area with emerging data and increasing complexity is the question of how to manage STEMI and non-ST-segment elevation myocardial infarction (NSTEMI) patients with multivessel disease after the culprit artery is treated. The 2016 AUC segregate out the decision-making into the acute phase of STEMI and later in the hospitalization. It applies only the CvLPRIT and PRAMI results to the acute setting,^5,6 when visual estimates drive the decision-making and allow for PCI of nonculprit lesions of 50% or more. After the acute phase, however, the treatment options are separated into scenarios 13 and 14; an intermediate stenosis is appropriate to be addressed with an FFR of less than 0.80. If no further ischemia testing or FFR are performed, it is considered rarely appropriate to treat an intermediate stenosis. Although one can readily understand this presumption, one can look at the data in a different manner. The only randomized FFR-guided study that has been done in this clinical context was the DANAMI-3-PRIMULTI,4 in which nonculprit revascularization was performed in the non-acute period. It is on the basis of this study that these recommendations are made. However, what I find interesting is that the angiographically driven studies (i.e., PRAMI and CvLPRIT, the latter of which did allow for staging) actually had a reduction in death and myocardial infarction whereas the FFR-guided strategy did not have a reduction in this hard endpoint. One could argue that perhaps the application of FFR in this acute setting is detrimental because there may be other unstable "nonculprit" lesions that are "FFR negative" but could benefit from revascularization. This could account for superior outcomes in the angiography-guided studies compared with the FFR-guided DANAMI-3-PRIMULTI. If you put this in the context of some recent data by Hakeem et al.¹³ that indicate that FFR may not be a good guide for deferral of ACS lesions and presume that some of these multivessel nonculprit lesions are also "hot," it may be that FFR recommendation can be questioned. Combining that with the recent data from the FUTURE study (Functional Testing Underlying Coronary Revascularisation)¹⁴ that indicate that there may be a hazard associated with FFR guidance in multivessel disease, this raises some very interesting questions in this arena. Of course there will be many subsequent studies addressing this with more robust data sets upcoming, which hopefully will resolve these issues and clarify these guidelines.

Lastly, it is gratifying to see that scenario 17 maintains a "may be appropriate care" for the low-risk patients with ACS with revascularization by PCI or CABG. One must remember that the latest American Heart Association and American College of Cardiology guidelines for stable ischemic heart disease (SIHD) have actually corralled the low-risk patient with ACS into the "stable" group.¹⁵ It has always been my feeling that this recommendation for treating these patients at low risk should be a matter of patient preference. However, basing this aggregation with SIHD on the lesser magnitude reduction of death or myocardial infarction than is seen in the patients with higher TIMI score does not account for the quality-of-life benefit attained in these low-risk patients with ACS with PCI, and it should be, in my mind, the preferred therapy.¹⁶

AUC Present Real-World Treatment Options
By Robert H. McQueen, MD, FACC, FSCAI
Mountain States Health Alliance
Johnson City, TN

The overall goal of AUC should be as stated in the document: "To form a framework for assessment of practice patterns to improve decision making." This updated guidance does an excellent job of attempting to categorize patients and disease states/severity into a "real-life" working metric of best treatment options during acute intervention using multiple clinical scenarios. They have also now appropriately separated stable angina guidelines from patients with acute/unstable angina in an attempt to better align subject matter with the most current American Heart Association and American College of Cardiology guidelines.

The treatment of multivessel disease found during acute PCI or unstable angina continues to be an ongoing interventional debate. These guidelines do an excellent job of reviewing all three of the recent studies (PRAMI, CvLPRIT, and DANAMI-3-PRIMULTI) as they relate to nonculprit lesions and various treatment options found during acute intervention. I do routinely discuss coronary anatomy with my patients, during both acute as well as stable interventions, to inform them of their best treatment options prior to PCI so that we may arrive together with a safe/suitable solution. In my experience, patients prefer to participate in their treatment plan and seem to "buy in" to altered lifestyles, medication usage, and possible staged procedures when given the opportunity to participate in the decision-making. These guidelines provide a framework for those options and suggestions of "appropriate care," "may be appropriate care," or "rarely appropriate care." Patient characteristics will always be variable, and treatment plans will never fit all; however, this framework is an excellent reference to improve decision-making and ultimately clinical practice.

I appreciate the committee's efforts to present real-world treatment options to patients with STEMI/unstable angina, especially as they relate to multivessel disease and nonculprit lesions, and the incorporation of shared decision-making into the guidelines. I find them beneficial and agree that they both reinforce and expand existing management strategies.

Appropriate and Inappropriate Implications of the New AUC
By Michael P. Savage, MD, FACC, FSCAI, FACP
Thomas Jefferson University Hospital
Philadelphia, PA

In late December, the Journal of the American College of Cardiology published an updated document on AUC for coronary revascularization in patients with ACS.¹ In previous versions, the collaborating societies published AUC for ACS and SIHD in a single document. The recent publication focuses only on patients with ACS; a separate publication on SIHD is expected later in 2017. An additional change in the new document is the use of recent modifications in the nomenclature for appropriate use categorization. In light of new data, the treatment of nonculprit vessels during STEMI is also re-examined. Previously, PCI of nonculprit lesions in STEMI patients in the absence of clinical instability or documented ischemia was assigned a class III recommendation (inappropriate). In the new publication, nonculprit vessel revascularization at the time of primary PCI is now classified as "may be appropriate care."

The writing group developed 17 clinical ACS scenarios that physicians commonly encounter in everyday practice. Of these, 10 were classified as "appropriate care," 6 were classified as "may be appropriate care," and only one was classified as "rarely appropriate care" for revascularization. The only "rarely appropriate care" rating was for the revascularization of nonculprit vessels in STEMI patients who were asymptomatic and had "intermediate severity" lesions (50-69% stenoses) without additional testing of the functional significance. What are the ramifications of these classifications? Clearly, with 16 of 17 scenarios considered "appropriate care" or "may be appropriate care" for revascularization, the document is a broad endorsement of coronary revascularization for ACS. Many interventionalists will interpret this document as a "green light" for not only culprit but also nonculprit revascularization in patients with a variety of ACS.

The current document is helpful in emphasizing the appropriateness of revascularization in high-risk patients with ACS, especially those with acute STEMI, NSTEMI, and clinical instability. However, in everyday practice, the diagnosis and therapy of lower-risk patients with presumed ACS is often not so straightforward. In the absence of an abnormal ECG or elevated troponins, a careful history and documentation of ischemia are imperative to determine whether a patient's chest pain is likely to be angina or non-cardiac. I have seen far too many patients treated with stents for "unstable angina" who in fact had atypical (non-cardiac) chest pain.

A concern and potential criticism of the current recommendations is the overreliance on the visual estimate of lesion severity as a prominent determining factor. This is particularly important in two common scenarios: (1) patients with chest pain without objective evidence of ischemia and (2) patients with acute myocardial infarction where revascularization of nonculprit lesions is contemplated. The visual estimate of stenosis severity is fraught with limitations. For starters, there is the well-recognized problem of reproducibility and interobserver variability.^17,18 One operator's 90% stenosis is another operator's 60% stenosis. Moreover, the estimated stenosis is an imperfect predictor of its functional significance. Studies using FFR testing have shown that most 50-70% stenoses are not functionally significant.¹⁹ According to the new AUC classification, stenoses >70% are considered "severe." However, even lesions with 71-90% stenosis are often not functionally significant by FFR.¹⁹ The FAME (Fractional Flow Reserve Versus Angiography for Multivessel Evaluation) trial, in which one-third of the patients had unstable angina, taught us the superiority of FFR over visual stenosis estimate in making treatment decisions.^20,21 FFR leads to better clinical outcomes at lower cost and avoids unnecessary interventions.

How does the new AUC document fit with current clinical practice? For most interventionalists, including myself, it reinforces the primary role of revascularization in STEMI and high-risk NSTEMI ACS. On the other hand, I am concerned that the emphasis on visual estimate of lesion severity may promote a new wave of unnecessary stent use in some patients.^22,23 For patients without objective evidence of ischemia or with less than ultra-severe lesions, the important roles for a careful clinical history, complementary stress testing, and FFR assessment must not be forgotten.

References

1. Patel MR, Calhoon JH, Dehmer GJ, et al. ACC/AATS/AHA/ASE/ASNC/SCAI/SCCT/STS 2016 Appropriate Use Criteria for Coronary Revascularization in Patients With Acute Coronary Syndromes: A Report of the American College of Cardiology Appropriate Use Criteria Task Force, American Association for Thoracic Surgery, American Heart Association, American Society of Echocardiography, American Society of Nuclear Cardiology, Society for Cardiovascular Angiography and Interventions, Society of Cardiovascular Computed Tomography, and the Society of Thoracic Surgeons. J Am Coll Cardiol 2017;69:570-91.
2. Amsterdam EA, Wenger NK, Brindis RG, et al. 2014 AHA/ACC Guideline for the Management of Patients with Non-ST-Elevation Acute Coronary Syndromes: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines. J Am Coll Cardiol 2014;64:e139-228.
3. Levine GN, Bates ER, Blankenship JC, et al. 2015 ACC/AHA/SCAI Focused Update on Primary Percutaneous Coronary Intervention for Patients With ST-Elevation Myocardial Infarction: An Update of the 2011 ACCF/AHA/SCAI Guideline for Percutaneous Coronary Intervention and the 2013 ACCF/AHA Guideline for the Management of ST-Elevation Myocardial Infarction. J Am Coll Cardiol 2016;67:1235-50.
4. Engstrøm T, Kelbæk H, Helqvist S, et al. Complete revascularisation versus treatment of the culprit lesion only in patients with ST-segment elevation myocardial infarction and multivessel disease (DANAMI-3—PRIMULTI): an open-label, randomised controlled trial. Lancet 2015;386:665-71.
5. Gershlick AH, Khan JN, Kelly DJ, et al. Randomized trial of complete versus lesion-only revascularization in patients undergoing primary percutaneous coronary intervention for STEMI and multivessel disease: the CvLPRIT trial. J Am Coll Cardiol 2015;65:963-72.
6. Wald DS, Morris JK, Wald NJ, et al. Randomized trial of preventive angioplasty in myocardial infarction. N Engl J Med 2013;369:1115-23.
7. Patel MR, Dehmer GJ, Hirshfeld JW, Smith PK, Spertus JA. ACCF/SCAI/STS/AATS/AHA/ASNC/HFSA/SCCT 2012 Appropriate use criteria for coronary revascularization focused update: a report of the American College of Cardiology Foundation Appropriate Use Criteria Task Force, Society for Cardiovascular Angiography and Interventions, Society of Thoracic Surgeons, American Association for Thoracic Surgery, American Heart Association, American Society of Nuclear Cardiology, and the Society of Cardiovascular Computed Tomography. J Am Coll Cardiol 2012;59:857-81.
8. Hochman JS, Lamas GA, Buller CE, et al. Coronary intervention for persistent occlusion after myocardial infarction. N Engl J Med 2006;355:2395-407.
9. Abbate A, Biondi-Zoccai GG, Appleton DL, et al. Survival and cardiac remodeling benefits in patients undergoing late percutaneous coronary intervention of the infarct-related artery: evidence from a meta-analysis of randomized controlled trials J Am Coll Cardiol 2008;51:956-64.
10. Ndrepepa G, Kastrati A, Mehilli J, Antoniucci D, Schömig A. Mechanical reperfusion and long-term mortality in patients with acute myocardial infarction presenting 12 to 48 hours from onset of symptoms. JAMA 2009;301:487-8.
11. Werner GS, Surber R, Ferrari M, Fritzenwanger M, Figulla HR. The functional reserve of collaterals supplying long-term chronic total coronary occlusions in patients without prior myocardial infarction. Eur Heart J 2006;27:2406-12.
12. Mark DB, Pan W, Clapp-Channing NE, et al. Quality of life after late invasive therapy for occluded arteries. N Engl J Med 2009;360:774-83.
13. Hakeem A, Edupuganti MM, Almomani A, et al. Long-Term Prognosis of Deferred Acute Coronary Syndrome Lesions Based on Nonischemic Fractional Flow Reserve. J Am Coll Cardiol 2016;68:1181-91.
14. Rioufol G, Mewton N, Rabilloud M, et al. Functional testing underlying revascularization: the FUTURE trial (TCTMD website). 2016. Available at: https://www.tctmd.com/slide/functional-testing-underlying-revascularization-future-trial. Accessed January 13, 2017.
15. Fihn SD, Blakenship JC, Alexander KP, et al. 2014 ACC/AHA/AATS/PCNA/SCAI/STS focused update of the guideline for the diagnosis and management of patients with stable ischemic heart disease: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines, and the American Association for Thoracic Surgery, Preventive Cardiovascular Nurses Association, Society for Cardiovascular Angiography and Interventions, and Society of Thoracic Surgeons. Circulation 2014;130:1749-67.
16. Pursnani S, Korley F, Gopaul R, et al. Percutaneous coronary intervention versus optimal medical therapy in stable coronary artery disease: a systematic review and meta-analysis of randomized clinical trials. Circ Cardiovasc Interv 2012;5:476-90.
17. Zir LM, Miller SW, Dinsmore RE, Gilbert JP, Harthorne JW. Interobserver variability in coronary angiography. Circulation 1976;53:627-32.
18. Leape LL, Park RE, Bashore TM, Harrison JK, Davidson CJ, Brook RH. Effect of variability in the interpretation of coronary angiograms on the appropriateness of use of coronary revascularization procedures. Am Heart J 2000;139:106-13.
19. Tonino PA, Fearon WF, De Bruyne B, et al. Angiographic versus functional severity of coronary artery stenoses in the FAME study fractional flow reserve versus angiography in multivessel evaluation. J Am Coll Cardiol 2010;55:2816-21.
20. Tonino PA, De Bruyne B, Pijls NH, et al. Fractional flow reserve versus angiography for guiding percutaneous coronary intervention. N Engl J Med 2009;360:213-24.
21. Sels JW, Tonino PA, Siebert U, et al. Fractional flow reserve in unstable angina and non-ST-segment elevation myocardial infarction experience from the FAME (Fractional flow reserve versus Angiography for Multivessel Evaluation) study. JACC Cardiovasc Interv 2011;4:1183-9.
22. Bishop T. Federal Report on Stent Procedures Finds Potential Fraud (Baltimore Sun website). December 6, 2010. Available at: http://www.baltimoresun.com/health/bs-md-senate-stent-report-20101205-story.html. Accessed February 2, 2017.
23. Waldman P, Armstrong D, Freedberg SP. Deaths Linked to Cardiac Stents Rise as Overuse Seen. (Bloomberg website). September 26, 2013. Available at: https://www.bloomberg.com/news/articles/2013-09-26/deaths-linked-to-cardiac-stents-rise-as-overuse-seen. Accessed February 2, 2017.

Keywords: Acute Coronary Syndrome, Angina, Stable, Angina, Unstable, Angiography, Angioplasty, Arteries, Avena, Catheterization, Constriction, Pathologic, Coronary Artery Bypass, Coronary Artery Disease, Electrocardiography, Heart Failure, Myocardial Infarction, Myocardium, Myocardial Infarction, Percutaneous Coronary Intervention, Thrombolytic Therapy, Troponin

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