Preoperative Cardiac Evaluation and Management of the Patient Undergoing Major Vascular Surgery

About 313 million major surgical procedures are performed worldwide every year.1 Since the 1970s, vascular surgery has been identified as a subpopulation with disproportionately elevated risk.2,3 This risk persists today. For example, in the Vascular Events in Noncardiac Surgery Patients Cohort Evaluation (VISION) study of over 15,000 individuals undergoing major noncardiac surgery, vascular surgery was a predictor of 30-day mortality adjusted hazard ratio (HR)=2.38.4 An analysis of about 123,500 cases in the National Surgical Quality Improvement Program (NSQIP) database from 2007 to 2010 revealed the absolute risk for death within 30 days after major vascular surgery to be 3%.5 Importantly, procedure-specific risks do vary considerably on the basis of the operative site, approach employed, and urgency of the procedure.6 An important reason for the elevated risk in vascular surgery patients is their burden of atherosclerotic disease. Many vascular surgical procedures address complications of peripheral arterial disease (PAD) or cerebrovascular disease (CVD). Atherosclerosis is the pathophysiological mechanism for both entities, as well as for coronary artery disease (CAD). Atherosclerosis involves plaques forming dense deposits in arterial walls and irreversibly expanding, subsequently leading to a narrowed vessel lumen and decreased compliance. Although atherosclerosis is not a regional process, it is defined in such terms; hence, the distinction between CAD, CVD, and PAD. Nonetheless, given their shared pathophysiology, there is a high association between CAD, CVD, and PAD.7 In the nonoperative setting, asymptomatic PAD is associated with a 3- to 4-fold increase in the risk of CAD and CVD.8 Further, the presence of PAD is a predictor of worse outcomes after both myocardial infarction (MI) and stroke.9,10 Thus, atherosclerosis in multiple organ systems is indicative of both disease breadth and severity. Because of the high risks of vascular surgery and the complex phenotype of patients undergoing these operations, it is imperative that anesthesiologists perform a thorough preoperative evaluation. The purpose of the preoperative assessment is to identify potential problems, ensure the patient is willing and able to tolerate the procedure with associated risks, mitigate perioperative risks, and facilitate appropriate postoperative monitoring. Given the influence of cardiovascular disease on outcomes in vascular surgery, it is important to identify individuals at risk to ensure appropriate management. Moreover, in individuals identified as being at very high risk, a frank discussion between the patient, surgeon, and anesthesiologist may be needed regarding the risks of the procedure, as well as possible alternatives to planned surgery. The goal of this chapter is to present an evidence-based approach to preoperative cardiac evaluation and management of patients undergoing major vascular surgery. Where possible, we focus on relevant current evidence and guidelines. The purpose is to present an approach to evaluate patients for common cardiac diseases and inform preoperative management. Thus, we will not discuss relatively uncommon cardiac diseases (eg, pulmonary hypertension, congenital heart disease), although these conditions are still important for perioperative care. Finally, we will assume sufficient time to complete a formal evaluation and permit management; however, we recognize this is often not the case. When discussing the urgency of cases, we use the definitions in the 2014 American College of Cardiology (ACC) and American Heart Association (AHA) perioperative guidelines. An emergency procedure is defined as threatening life or limb and requiring the patient to be in the operating room within 70% stenosis in ≥1 major coronary artery).23 Consistent with this observation, a randomized controlled trial (RCT) of routine preoperative coronary angiography for major vascular surgery found significant stenosis of a major coronary artery in 62% of individuals allocated to routine screening.24 Thus, a high index of suspicion for undiagnosed CAD is needed in vascular surgery patients. The primary concern regarding CAD stems from it being a risk factor for postoperative death,4 MI,16 and myocardial injury after noncardiac surgery.17 Perioperative MI after vascular surgery has a mortality of 10% to 25%.25,26 Further, it is a strong predictor of elevated early (in-hospital or 30-d) and long-term mortality.25–31 The newer clinical entity of myocardial injury after noncardiac surgery (ie, significant troponin elevations after noncardiac surgery) is also associated with elevated 30-day mortality. Notably, cardiovascular complications are the leading cause of death after major vascular surgery.32–34 When evaluating a patient with known or suspected CAD, the preoperative assessment should begin with a history regarding specific symptoms of CAD, prior events, diagnostic tests, previous interventions, and treatment. It is important to characterize the presence, frequency, precipitants, and duration of angina. Communication between clinicians is often facilitated by standardized scales such as the Canadian Cardiovascular Society grading system for rating the severity of angina.35 Further, it is essential to document any temporal change in symptoms to differentiate stable angina from unstable angina. As a prior MI is a risk factor for perioperative cardiac morbidity, it is important to document the date of any cardiac events and revascularization procedures. The impact of a prior MI on subsequent noncardiac surgery depends on the interval since the MI and any revascularization procedures. The impact of the interval from a prior MI on perioperative risk is informed by a large retrospective cohort study of 563,842 surgical procedures; abdominal aortic aneurysm (AAA) repair surgery was among the 5 procedures included in the study.36 A previous MI within 30 days of surgery was associated with a dramatic increase in 30-day MI after AAA repair adjusted relative risk (RR)=15.36; the risk was still elevated, albeit not to the same degree, for a previous MI within 31 to 60 days before surgery (adjusted RR=4.5). These data support current guideline recommendations to delay nonurgent major noncardiac surgery for at least 60 days after an MI.11 As indicated above, it is important to document the timing of any prior revascularization procedure with percutaneous coronary interventions (PCI) or coronary artery bypass graft (CABG) surgery. If PCI was performed, it is imperative to determine whether a bare metal stent (BMS) or drug eluting stent (DES) was inserted. The distinction between stent types determines the recommended minimum duration of dual antiplatelet therapy with aspirin plus a P2Y12 inhibitor (eg, clopidogrel, prasugrel). The concern regarding prior PCI stems from the potential need to interrupt dual antiplatelet therapy, which along with the prothrombotic state generated from the stress of surgery increases the risk for catastrophic acute stent thrombosis. Recent practice guidelines recommend that time-sensitive and elective noncardiac surgery be delayed for at least 30 days after insertion of BMS, after which patients can proceed to surgery on aspirin alone.11,37 These recommendations are supported by recent large multicenter retrospective cohort studies.38,39 Conversely, evidence regarding the minimum safe interval from DES insertion to noncardiac surgery continues to evolve. The 2009 ACC/AHA guidelines on perioperative cardiovascular evaluation recommended a minimum 1-year interval from DES insertion to surgery.37 Several subsequent large cohort studies then found that noncardiac surgery can be performed safely once >180 days had elapsed from DES insertion.38–40 Combined with other nonrandomized studies,39,41,42 these data support the current new guideline recommendation to ideally delay elective noncardiac surgery until at least 365 days after DES, with the provision that surgery can proceed after 180 days in selected cases.11 Another important predictor of outcomes in CAD is exercise capacity. As early as 1989, a study of exercise testing in 100 patients undergoing major vascular surgery found that preoperative exercise tolerance was inversely proportional to the risk for MACE.43 Other studies have shown that the ability to perform >4 to 6 metabolic equivalents (METs) on objective exercise testing was associated with low perioperative cardiovascular risk.44,45 The key challenge in clinical practice is identifying individuals with poor exercise capacity using clinical evaluation alone, as opposed to formal exercise testing. The conventional assessment of exercise capacity involves physicians making a subjective estimate based on patients’ self-reported history. The data supporting the prognostic accuracy of subjective estimates of exercise capacity are relatively weak. A single-center study of 600 patients undergoing noncardiac surgery did show patients’ self-reported inability to climb 2 flights of stairs or walk 4 blocks to be a risk factor for perioperative cardiovascular complications (adjusted OR=1.9).46 Nonetheless, when expressed as a likelihood ratio (LR), self-reported poor exercise capacity had a positive LR of 1.3 and negative LR of 0.62 for predicting complications. LR values >2 or <0.5 are recommended for providing even minimal additional information.47 Further, another single-center study of 5939 surgical patients found physicians’ subjective estimates of exercise capacity to have minimal to poor accuracy at predicting mortality or cardiac complications.48 A potential improvement encouraged by guidelines is objective scales with correlation to objectively measured exercise capacity,11 such as the Duke Activity Status Index (DASI).49 The use of a questionnaire, as opposed to subjective assessment, can lead to different estimates of exercise capacity. A single-center study of 74 surgical patients found poor agreement between subjective physician assessment and the DASI, with a tendency of the former to underestimate capacity.50 Despite these limitations, it remains important to evaluate exercise capacity, especially to inform decisions regarding the need for further investigation. In addition to the routine cardiac examination, the physical examination for a patient with known or suspected CAD should assess for other cardiovascular disease. The pulse should be examined to assess for regular sinus rhythm. Particular attention should be paid to signs of heart failure (HF) and valvular disease (see the HF section and valvular heart disease section). Baseline vital signs, particularly blood pressure, should be recorded to inform perioperative hemodynamic management and assess therapeutic control in hypertensive patients. The main utility of documenting the baseline blood pressure is to guide anesthesiologists in maintaining hemodynamics within an individual’s normal physiological range. This goal is increasingly important given accumulating evidence that intraoperative hypotension is associated with major morbidity after noncardiac surgery.51–53 Heart Failure (HF) HF can result from many different etiologies, each with specific implications. During preoperative evaluation, HF is best characterized with respect to associated symptoms and the nature of ventricular impairment. Classically, HF was divided into systolic HF, when ventricular systolic dysfunction was present, and diastolic HF, when ventricular filling is impaired. Diastolic HF has generally not received much attention in the perioperative literature, despite being much more common than previously understood and accounting for half of all cases of HF.54 After recent investigations showed the pathophysiology of diastolic HF to involve a much broader range of factors than impaired ventricular filling, there has been a shift in the terminology of HF. Diastolic HF is now described as HF with preserved ejection fraction (EF). A distinction is made from HF with systolic dysfunction, which is now termed HF with reduced EF.54 The type of HF is important for management and has implications for life expectancy. In an individual patient meta-analysis of 41,927 patients, survival was significantly better for HF with preserved versus reduced EF (adjusted HR=0.68). Nonetheless, it should be emphasized that the absolute mortality for HF with preserved EF was still elevated.55 This terminology is still highly debated and may represent an ongoing evolution in the understanding of HF.56,57 Although the distinction between HF with preserved versus reduced EF has facilitated targeted therapeutic intervention, its relevance for perioperative management remains to be thoroughly investigated. HF has been recognized as a risk factor for perioperative MACE for almost 40 years.3 Goldman et al3 reported it as one of 9 major risk factors for perioperative MACE, with the presence of HF defined by a third heart sound (S3) or jugular venous distension. Further, HF represents one of the 6 risk factors included in the commonly used Revised Cardiac Risk Index (RCRI), where the definition was broadened to include physical findings (bilateral rales, S3 gallop), radiographic evidence (pulmonary vascular redistribution), and a history of HF, pulmonary edema, or paroxysmal nocturnal dyspnea.16 Symptomatic HF continues to be identified as a risk factor for adverse perioperative outcomes in multiple studies. For example, in a retrospective cohort study of about 47,800 Medicare beneficiaries in the United States, a history of HF was associated with a doubling in the risk for 30-day death after noncardiac surgery (adjusted OR=2.19).58 A subsequent larger study also showed a history of HF to be associated with a qualitatively similar increase in the risks for 30-day mortality in about 159,300 Medicare beneficiaries.59 Most recently, a matched cohort study using the NSQIP registry showed new or worsened HF within 30 days before surgery to be associated with increased risk for 30-day mortality (adjusted RR=2.08) or major morbidity (adjusted RR=1.54).60 The stability of patients’ HF status immediately before surgery may also have prognostic importance. In a pragmatic study of 567 patients with HF who underwent elective noncardiac surgery, Xu-Cai and colleagues61 evaluated the impact of a specialized preoperative clinic intended to stabilize patients before surgery. The results suggest that preoperative medical management to achieve stability is important, as HF patients and propensity-matched controls did not have significant differences in 30-day mortality. Nonetheless, hospital length of stay and readmission rates remained higher for the HF patients. Although symptomatic HF is clearly a marker of increased perioperative morbidity, the impact of reduced left ventricular EF is less clear. To study the impact of left ventricular EF on perioperative outcomes, Healy and colleagues studied 174 patients with HF undergoing noncardiac surgery, of whom 47% had vascular surgery. An EF<30% was associated with the composite outcome of 30-day death, MI, and HF (adjusted OR=4.88).62 Conversely, in another cohort study of 339 individuals undergoing noncardiac surgery, a reduced EF was associated with increased cardiac morbidity, but this information did not improve risk prediction beyond that achieved with clinical risk factors.63 In another cohort study of 570 individuals undergoing noncardiac surgery, a reduced EF had prognostic importance only in individuals with at least 2 risk factors from the RCRI.64 In summary, the prognostic relevance of asymptomatic left ventricular dysfunction in the perioperative setting is unclear. A preoperative assessment for HF should include a history to clarify its type, etiology, prior exacerbations, and recent investigations (eg, prior ventricular function measurements). The severity of and recent changes in HF symptoms should be documented, including paroxysmal nocturnal dyspnea, orthopnea, and lower extremity edema. Current therapy should be assessed, with particular attention paid to drugs with perioperative implications (see the pharmacologic therapy section). Potential therapies may include cardiac resynchronization therapy, which will require appropriate perioperative management. Functional to HF should be characterized using the Heart Association system to a standardized If a patient exercise of (eg, left ventricular EF is not a of exercise The findings of HF on physical examination may be but signs are in making the precordial a S3 is the predictor of HF with a positive LR of If there is regarding the presence of HF, a may further In patients, both pulmonary vascular and increase the likelihood of If the cause for still remains can be for between cardiac and noncardiac Heart During the preoperative evaluation, it is important to ascertain any known cardiac valvular disease a history and precordial In individuals with known disease, HF exercise capacity, findings (ie, valvular ventricular pulmonary and therapy (eg, should be It is especially important to identify valvular that the ability of patients to for the of particular concern is aortic which is the most common valvular in aortic stenosis has been a recognized risk factor for perioperative morbidity for almost 40 years.3 These risks in a single-center cohort of about patients who underwent noncardiac surgery with aortic with matched individuals with aortic stenosis significantly higher risk for death or MI within 30 days after surgery. Conversely, 2 other single-center studies patients in that selected patients with aortic stenosis noncardiac surgery with rates of morbidity and Thus, the to perform preoperative aortic versus to vascular surgery with aortic stenosis the severity of the valvular level of perioperative (eg, cardiac intraoperative as well as the urgency and of the planned vascular In an individual known valvular heart disease, a systolic ejection on precordial examination should always the suspicion of undiagnosed aortic Although such individuals should ideally for diagnostic evaluation, physical examination can help to severe aortic a clinical found that the absence of a below the has a negative LR of to for significant The preoperative assessment should include a history of prior significant It should be whether the is or in the any hemodynamic and should be can be as ventricular or is associated with increased cardiac risk in noncardiac For example, in the preoperative was associated with increased risk for MACE (adjusted It is important to the presence of medical therapy (ie, and any cardiac The may be a or a The and of any should be along with the current and to a on perioperative management are in guidelines from the American Society of and Heart examination should assess signs of HF (see the HF and murmurs of valvular disease. patients with fibrillation, the index has in risks for postoperative stroke or This information has the potential to inform selection of individuals requiring perioperative Nonetheless, the of has been into by the recent in Patients who of for an or Surgery which showed perioperative of to be to therapy in Preoperative Risk Assessment Given the elevated morbidity and mortality associated with vascular surgery, risk assessment is a in the preoperative the risk of the surgical procedure is essential to between clinicians and patients regarding the risks versus of the planned surgery, making it to an informed Further, a patient can be identified before surgery, appropriate and can be the intraoperative and the level of postoperative can be after surgery. Risk As there is potential utility of an preoperative risk it is not that many have been The is generally the these identified as predicting the outcome of These factors can be more into patient (eg, and procedure (eg, vascular surgery) It has been almost 40 since the Goldman Cardiac Risk Index was the preoperative evaluation and providing the for a new of Although many more have been the most used cardiac risk index in practice is the This of 6 surgery or vascular history of CAD, history of HF, history of CVD, requiring with and preoperative The well in based on risk for postoperative cardiac complications, with preserved in studies based on a the operating of it has the has poor accuracy for predicting an individual’s absolute cardiac For example, it cardiac rates by to in 2 2 of the have not shown in the of requiring with and preoperative in the index is although the with reduced improve Finally, the has shown poor in vascular surgery, particularly AAA repair Despite these limitations, a index in vascular surgery, with its main its and In a new index was for vascular surgery the Vascular Surgery of Cardiac Risk Index The index was in a cohort that included carotid lower extremity AAA and aneurysm repair The factors in the index CAD, HF, pulmonary disease, requiring therapy, preoperative therapy, and prior or in a cohort of patients showed only which was not significantly with