Preoperative management of antiplatelet drugs for a coronary artery stent: how can we hit a moving target?

A recent systematic review identified 11 clinical practice guidelines for the perioperative management of antiplatelet therapy in patients with a coronary stent who need non-cardiac surgery [12]. These authors applied the Appraisal of Guidelines Research and Evaluation II (AGREE II) instrument (with a maximum score of 161) to assess the quality of the identified guidelines [12], Five of the 11 practice guidelines had an AGREE II score of > 100: American College of Chest Physicians [13], American College of Cardiology/ American Heart Association (ACC/AHA) [14], Canadian Cardiovascular Society [15], European Society for Cardiology [16], and Institute for Clinical Systems Improvement [17]. The Society of Thoracic Surgeons has also published updated guidelines on the management of antiplatelet therapy in cardiac and non-cardiac surgical patients [18].

However, despite some having AGREE II scores of greater than 100, a paucity of available definitive evidence has resulted in perioperative coronary artery stent guidelines that are divergent and vague on key issues. Recommendations vary regarding the amount of time which must elapse between stent placement and elective surgery in order to have an acceptable risk of acute stent thrombosis when dual antiplatelet therapy (DAPT) is discontinued. If DAPT must be interrupted within this critical period due to the risk of bleeding, the recommended timing of aspirin and thienopyridine discontinuation also varies.

These existing guidelines provide well-defined—albeit contradictory—recommendations on how long elective procedures should be delayed following coronary stent placement. However, for patients needing urgent surgery, while still presumably requiring DAPT, the recommendations concerning antiplatelet medications become vague. Most of the guidelines simply advise somehow weighing the risk of stent thrombosis against the risk of bleeding and, if at all possible, continuing the DAPT therapy throughout the perioperative period. The most current ACC/AHA guidelines [14, 19] do thoroughly review many of the risks associated with both stent thrombosis and surgical bleeding, but the incorporation of these risks into the final recommendations is incomplete.

Developing such clinical practice guidelines is a highly-structured, labor intensive process, involving a rigorous review and critical appraisal of the literature, multidisciplinary consultation, and grading of the resulting recommendations based on the quality of available evidence [20]. Nevertheless, persistently variable success has been experienced in translating even well-grounded national clinical guidelines into local practice, including in the perioperative setting [21]. Barriers to providers adopting such clinical guidelines include inadequate understanding, lack of agreement and perceived “real-world” practicality, concerns about loss of self-efficacy, low outcome expectations, and the inertia of existing practice [22].

In an October 2010 survey of United States Department of Veterans Affairs network physicians, 100% of anesthesiologists, 100% of cardiologists, but only 78% of surgeons were aware of the then current ACC/AHA Guidelines on Perioperative Cardiovascular Evaluation and Care for Noncardiac Surgery [23]. Furthermore, among the survey respondents, 87% of anesthesiologists, 90% of cardiologists, but only 64% of surgeons agreed with these published guidelines. There was also significant variability among the three specialties in the perception of risk of coronary stent thrombosis versus bleeding and in the perioperative continuation of antiplatelet therapy with a BMS or a DES—with anesthesiologists and cardiologists emphasizing stent thrombosis risk and more often electing to continue antiplatelet therapy [23]. Anecdotally, at our institution, we had encountered minimal success in achieving consistent adherence to these same previously published ACC/AHA clinical practice guidelines for the preoperative management of patients with a coronary artery stent.

Neuman and colleagues at the University of Pennsylvania have observed that the durability of class I guideline recommendations for procedures and treatments, promulgated by the ACC/AHA, have varied widely across individual guidelines and levels of evidence [24]. Specifically, of 619 such ACC/AHA recommendations examined, 80.0% were retained in the subsequent guideline version, 9.2% were downgraded or reversed, and 10.8% were omitted. Downgrades, reversals, and omissions were most common among recommendations that were not supported by multiple randomized studies [24]. As noted in the accompanying editorial, in order for practice guidelines to be most effective, they need to be kept up-to-date [25].

The Institute of Medicine (IOM) has recommended that clinical practice guidelines should be updated when new evidence suggests the need for modification of such clinically important recommendations [26]. However, as noted in the above editorial: “But what does this mean, and how is it best accomplished?” [25]. To address this, three additional key questions should be considered: (1) When is there sufficient new evidence to “trigger” an update; (2) Once a trigger has been met, what methods can be used to expeditiously produce the update; (3) Once the update is completed, how is the information best communicated to relevant stakeholders? [25].

We posit that a standardized clinical assessment and management plan represents a viable response to the second and third key questions.

In contrast to professional society practice guidelines, a standardized clinical assessment and management plan (SCAMP) provides for a more “homegrown,” local clinician-designed and clinician-driven, yet rigorous alternative approach to achieving evidence-informed best practice for a heterogeneous patient population [27]. Clinicians are more likely to adopt practice guidelines that combine existing evidence and expert opinion in a format that can be readily revised. An iterative SCAMP hence accommodates local patients’ individual and population differences, respects local providers’ clinical acumen, and keeps pace with the rapid growth of medical knowledge [28]. For example, the published ACC/AHA guidelines, which were included in the above systematic review of perioperative management of antiplatelet therapy, date back to 2007/2009 [12, 14]. These existing ACC/AHA guidelines are currently undergoing revision.

With this in mind, under the auspices of a broadly multidisciplinary Anticoagulation Task Force at the University of Alabama at Birmingham (List of Stakeholder), we created two current evidence-informed yet also local expert opinion-supported SCAMPs: one focused on preoperative antiplatelet therapy with a BMS (Figure 1) and one focused on preoperative antiplatelet therapy with a DES (Figure 2). In that this continuous quality improvement (CQI) project was not human subjects research, approval was not obtained from the Institutional Review Board of the University of Alabama at Birmingham.

Health System Chief of Staff

Anesthesiology

Cardiology

Critical Care Medicine

General Surgery

Hospitalist Medicine

Pain Medicine

Pathology

Pulmonary Medicine

Transfusion Medicine

Vascular Surgery

Over a 12-month period, our multidisciplinary anticoagulation task force applied the Consensus-Oriented Decision-Making (CODM) model to arrive at a consensus among the local clinical stakeholders. A detailed, step-wise process, the CODM model can be applied in any type of decision-making process (Figure 3). It outlines a process in which proposals can be collaboratively built with full participation of all stakeholders [29]. Consensus decision-making does not require unanimity but instead seeks the agreement of the majority of participants as well as the resolution or mitigation of minority held objection [30]. We took into consideration previously published applicable guidelines and other literature to create two evidence-informed protocols (see Additional file 1). These two protocols are presented here as suggested clinical management approaches.