The perioperative management of patients who are receiving antiplatelet therapy is a common clinical problem given the large number of patients who are receiving these agents for treatment of coronary artery disease, cerebrovascular disease or peripheral arterial disease. Such patients may be receiving: acetylsalicylic acid (ASA) alone; clopidogrel alone; ASA and clopidogrel. Patients who are receiving antiplatelet drugs encompass a broad risk spectrum for cardiovascular events that depends on the clinical indication for antiplatelet therapy and whether patients are receiving treatment for the primary or secondary prevention of cardiovascular disease. There are no perioperative risk classification schemes that consider the benefits and risks of continuing or interrupting antiplatelet therapy.

The objectives of this chapter are: 1) to stratify patients according to their risk for acute coronary events if antiplatelet therapy is stopped and the risk for bleeding associated with surgery or procedure; and 2) to provide a practical approach to the perioperative interruption and resumption of antiplatelet therapy.

Perioperative Atherothrombotic Risk Assessment

Patients who are receiving antiplatelet drugs have a variable risk for atherothrombotic cardiovascular events, which depends to a large extent on the indication for the antiplatelet therapy. Although an overall risk classification scheme for atherothrombotic events does not exist, it is reasonable to consider patients who are receiving antiplatelet therapy as primary prevention against stroke or myocardial infarction as being at lowest risk for atherothrombotic events. On the other hand, patients considered at high risk for such events include those with a recent acute coronary syndrome, in particular within the past 3 months, and those with a recent placement of a coronary stent, in particular within the past 6 weeks to 6 months (Table 62-1).

Bleeding Risk Assessment

Along with patient-specific characteristics, such as concomitant liver or kidney disease, an assessment of the perioperative bleeding risk depends largely on the type of surgery or procedure being performed. In assessing surgery/procedure-specific bleeding risk, 2 factors should be considered: the expected amount of blood loss; and the location of the surgery/procedure. Thus, the amount of bleeding is important as it can lead to local complications such as a wound hematoma or systemic complications such as cardiovascular collapse. The site of bleeding is also important if a procedure may involve the brain, spinal cord, or heart, as even a small amount of intracranial, spinal, or pericardial bleeding can have devastating clinical consequences.

Although there is no validated method to quantify perioperative bleeding risk, special attention is warranted for certain surgical or other invasive procedures associated with a high risk of bleeding. These can be categorized into 4 groups: (I) extensive surgery associated with substantial tissue damage such as major orthopedic surgery, reconstructive plastic surgery, and major cancer surgery; (II) urologic surgery such as prostate and bladder surgery (including endoscopic surgery); (III) “closed-space” surgery such as that which is intracranial, spinal, posterior chamber of the eye, and cardiac (coronary artery bypass or heart valve replacement) surgery; and (IV) major vascular surgery, such as aortic aneurysm repair.

A suggested classification of bleeding risk can be considered in Table 62-2. In addition, there are some minor surgeries or procedures that, on the surface, may not appear to confer an increased risk for bleeding but warrant caution when perioperative anticoagulation is used. Resection of colonic polyps, especially those with large sessile stalks, may confer significant bleeding since after the stalk is transected. In patients having a biopsy of the prostate or kidney, endogenous production of urokinase within the urinary tract may promote bleeding for up to 1 week after the procedure while healing takes place at the biopsy site. In patients having a cardiac pacemaker or defibrillator implantation, the subclavian pocket that is dissected between the fascial layers is left unopposed to heal by secondary intention making patients susceptible to pacemaker pocket hematoma.