During the past 2 decades, mortality related to cardiovascular disease has decreased significantly. Coronary bypass, catheter-based coronary interventions, and improved use of medications (including the use of new classes of medications) have all contributed to the success. During that same time, improvements in anesthetic and surgical techniques and life-support methods have helped to reduce the risk of operation. Conditions that would have been absolute contraindications to surgical treatment years ago, including advancing age, are now only relative contraindications. The decision to proceed with a noncardiac operation has always necessitated careful consideration of the specific surgical procedure being contemplated, anesthetic techniques and their associated stress on the heart and lungs, and overall perioperative risk, including peri operative myocardial infarction and other organ system dysfunction or failure.
In the past, when diagnostic technology and therapeutic interventions were limited, the paramount responsibility of physicians caring for patients in the perioperative period was to identify clinical factors that could be anticipated and controlled in order to reduce overall stress on the heart and lungs. In recent years, however, the development of better noninvasive tests of cardiac function and the application of catheter-based coronary interventional techniques have caused greater concern for physicians as they prepare patients for noncardiac surgery. The array of choices of cardiac diagnostic and therapeutic procedures creates its own uncertainty for physicians.
Guidelines.—The American College of Cardiology/ American Heart Association guidelines for perioperative cardiovascular evaluation for noncardiac surgery in this issue of the Mayo Clinic Proceedings (pages 524 to 531) offer recommendations for physicians who are preparing patients for noncardiac surgery and a framework for assessment of future outcomes. Several important observations can be made regarding these guidelines. First, in an era of increasing concern about overall cost, these guidelines emphasize the selection of preoperative and perioperative interventions based on careful consideration of clinical circumstances rather than simply suggesting the least expensive approach. These guidelines recognize that it is appropriate in some situations to proceedwith an aggressive evaluation, including preoperative coronary angiography, and in other cases to postpone the noncardiac surgery to allow treatment of an underlying cardiac condition that may have been discovered for the first time during a preoperative assessment.
Second, the summarized guidelines are based on a thorough review of available information. The authors recognize appropriately that, in many circumstances, information from randomized trials on which to base a diagnostic or therapeutic decision is lacking and that certain procedures have been used too infrequently to make an accurate representation of their utility.
Third, the guidelines suggest that reasonable alternatives are available that will provide the necessary clinical information (for example, dobutamine echocardiography and pharmacologic stress thallium procedures).
Use of Guidelines.—Utility of guidelines in medical practice is greatest when recommendations can be incorporated in a practical fashion in daily practice, when the guidelines can truly direct clinical decision making, and when the guidelines are structured in such a way to allow measurement of outcomes within individual practices as well as comparison of practices at major institutions. Although randomized trials may never be possible for some conditions, the use of guidelines for the collection of information in an observational fashion may be extremely helpful in assisting clinicians with future decisions. Thus, several practical considerations exist for the implementation of these guidelines into practice. The steps that are described and the tables that are presented in the article by Eagle and associates create the possibility of a simple framework that can be used in redesigning history forms—paper ones or even patient-provided information in electronic records. For example, the estimated data entry requirements summarized in Table 2 can easily be translated into simple questions that can allow a clinician to assess the capability of a patient to perform 4 metabolic equivalents of activity without cardiac symptoms. The clinical predictors of increased perioperative risk listed in Table 1 can also be easily transformed into a set of questions that can be rapidly completed. The risk stratification related to specific surgical procedures in Table 3 can be incorporated into a simple format that would enable primary-care physicians, surgeons, or anesthesiologists to help select patients for referral to a cardiologist for further advice about cardiac evaluation or methods to reduce perioperative risk in situations when noncardiac surgery is urgent.
Although these guidelines offer some practical and useful advice, uncertainties remain that are recognized by Eagle and colleagues. Physicians confronting these situations will need to make an appropriate decision based on their careful considerations of the clinical circumstances for their patient and their assessment of available historical information, physical examination findings, and other available information. Specifically, in patients who require urgent operative intervention and who have no evidence of an unstable coronary syndrome or uncontrolled heart failure, delaying necessary noncardiac surgery would be inappropriate particularly because it is unknown whether coronary revascularization would substantially reduce the perioperative risk (in some cases, the perioperative risk of coronary surgery may be equal to that of the noncardiac operation). When patients who are being considered for elective noncardiac surgery are found to have uncompensated heart failure, pronounced arrhythmias, or signs and symptoms of severe valvular or coronary disease, it is certainly appropriate to indicate that the cardiac risks of surgery are prohibitive, that the operation should be postponed until the cardiac status is sufficiently stabilized, and that all involved persons (patient, anesthesiologist, surgeon, primary-care physician, and cardiologist) are satisfied that the benefits of a noncardiac operation will outweigh the potential risks.
Overall, these guidelines emphasize that the most important consideration is to evaluate and treat heart disease as in the nonoperative setting. Thus, the clinician must ascertain that catheter-based coronary interventions, coronary bypass, or other cardiac surgical interventions would be reasonable options before invasive studies (coronary angiography) are considered.
Assessment of Patients.—Exhaustive monitoring of patients postoperatively in intensive-care units with use of repeated cardiac enzymes, electrocardiography, and other studies is generally unnecessary. The simplest approach is to use electrocardiography (when no severe ST-segment abnormality is noted on the preoperative tracing). Patients who have development of signs and symptoms of angina or cardiac dysfunction postoperatively should be reassessed and re-treated as in a nonoperative setting, with emphasis on understanding the risk of future cardiac events and use of myocardial revascularization or other therapies on the basis of carefully chosen diagnostic studies.
An unresolved issue is how to assess intermediate-risk patients, specifically those with one or two risk factors (Q waves on the electrocardiogram, angina, diabetes mellitus, advancing age [older than 70 years], and cardiac arrhythmias). With application of a modified approach, noninvasive testing can be used to enhance decision making.
- L'Italien GJ
- Paul SD
- Hendel RC
- Leppo JA
- Cohen MC
- Fleisher LA
- et al.
Development and validation of a Bayesian model for perioperative cardiac risk assessment in a cohort of 1,081 vascular surgical candidates.
On On the basis of currently available information, dipyridamole thallium or dobutamine stress echocardiography would be an excellent choice for the assessment of the patient with moderate clinical risk of perioperative myocardial infarction. The choice of technique should depend on the capability of diagnostic laboratories available to perform the service.
Summary.—The perioperative assessment and management of patients undergoing noncardiac surgery should emphasize a thorough clinical examination and judicious selection of tests based on determination of risk. For low-risk patients, no further testing is necessary. For high-risk patients who require urgent noncardiac surgery, proceeding with the operation is appropriate. If, however, the noncardiac surgical procedure can be postponed, the patient's underlying cardiac disease should be treated as in a nonoperative setting. In the preoperative evaluation, clinicians should consider the anesthetic and surgical factors that may necessitate careful attention in order to minimize stress on the heart and lungs. Finally, if clinicians will use these guidelines prospectively as a measurement framework to enhance their future decision making, then clinical outcomes in moderate-risk patients will be improved.