The patient with cardiovascular disease (CVD) presenting for lung resection surgery has special concern. Identifying significant cardiac risk factors provides information to better quantify the risks of a possible cardiac event in the perioperative period. Cardiac complications in the perioperative period may prolong recovery in the immediate postoperative period and may also affect outcome following the surgery. Over the past decades, research initially focused on identifying cardiac risk factors in patients with CVD presenting for noncardiac surgery (NCS). Recent research focused on randomized controlled trials identifying strategies to reduce perioperative cardiac complications. Cardiac risk is specific to each patient and to the extent of the surgery. Guidelines from the American College of Cardiology (ACC) and the American Heart Association (AHA) provide information and guidelines for the evaluation and management of the cardiac risk and best practices to reduce morbidity and mortality for patients with CVD presenting for NCS.¹ This chapter will outline risk assessment, identify appropriate noninvasive testing in patients with suspected or known coronary artery disease (CAD), and outline management of perioperative medical therapies to reduce the risk of cardiac complications during and after lung resection surgery including anticoagulation therapies.

Incidence

A national database review of over 10 million hospitalized patients from 2003 to 2014 presenting for NCS revealed a perioperative incidence of cardiovascular events of 3%.² Over 5% of major cardiac events (in-hospital, all cause death, acute myocardial infarction [MI], or acute ischemic stroke) occurred in thoracic, vascular, and transplant surgery. In addition, those with an estimated decrease in systolic function of less than 40% had a higher incidence of perioperative cardiac morbidity. The perioperative period is characterized by a catecholamine surge, prothrombotic milieu, altered platelet function, increased oxygen demand from fluctuating heart rate and blood pressure, as well as volume shifts and blood loss. This predisposes and contributes to a higher incidence of myocardial ischemia in patients with CVD. Patients with CVD, because of their underlying disease, have an increased risk of perioperative cardiac complications compared with those patients without CVD.²

Assessment of Risk

Every patient scheduled for lung surgery should have an assessment of risk of a cardiac event in the perioperative period. Many risk models have been developed over the past decades based on preoperative evaluation of patient history, physical examination, electrocardiogram (ECG), and type of surgery. The original cardiac risk index (CRI) was developed in 1977 by Goldman et al.³ and was known as the Goldman Index. It included nine variables associated with an increased risk of a cardiovascular event in the perioperative period. The Goldman index has been validated since its inception and was revised in 1999 by Lee et al.⁴ to include six independent variables and revised again by Davis et al.⁵ in 2013 to five variables. This simplified index of five independent variables was validated in 9519 patients over the age of 50 years undergoing major NCS with an expected length of stay longer than 2 days at two major tertiary teaching hospitals. Five independent variables were identified that predicted an increased risk for perioperative cardiac complications. The risk increased with the number of variables that were present in the patient (Table 30.1). Patients with less than 1% are in the low risk group and no further testing is required. In the higher risk group, further testing determines whether there will be a change in management and improved outcome, especially in the long term. Another model has been developed by the American College of Surgeons National Surgical Quality Improvement Program (ACS NSQIP) called the Gupta myocardial infarction or cardiac arrest (MICA) NSQIP database risk model.⁶ The NSQIP MICA is an online risk calculator that is comprehensive and procedure specific. It is based on a national database evaluation of risk factors in over 200,000 patients who underwent surgery in 2007. This study showed a 0.65% rate of perioperative MI or cardiac arrest. Five factors were associated with an increased risk of a perioperative MI or cardiac arrest:

• • Type of surgery
  
• • Functional status
  
• • Preoperative creatinine level
  
• • American Society of Anesthesiology (ASA) physical status classification
  
• • Increased age

The newer NSQIP MICA calculator is more comprehensive and cumbersome and includes over 20 patient risk factors, as well as surgical procedures. Also developed by the ACS, is the ACS NSQIP surgical risk calculator. This has not been externally validated because confounding factors, such as institution, surgeon experience, and different definitions of risk, complications, and outcomes may increase or lower the overall risk in the perioperative period. A comparison of Revised CRI, NSQIP MICA, and the NSQIP surgical risk calculator is shown in Table 30.2.

The Revised CRI remains the standard for assessing perioperative cardiac risk in the preoperative evaluation of the patient presenting for NCS. It also guides the decision for further testing and management protocols in preparing the patient for NCS.

Ischemic Heart Disease

The patient with coronary ischemic heart disease (CAD) may be evaluated by a primary caregiver or by a cardiologist. However, many patients are evaluated by the surgeon or anesthesiologist immediately before surgery. According to the Society of Thoracic Surgeons national database, the incidence of CAD in patients undergoing lung resection is greater than 20%.⁷ The preoperative evaluation should focus on identifying the presence of stable or unstable CAD because these patients have a higher risk of cardiac decompensation leading to a cardiac event in the perioperative period. In addition, the stress of undergoing a thoracic procedure may elevate the heart rate and further contribute to myocardial ischemia from an increase in oxygen demand in the symptomatic or asymptomatic patient. Identification of risk factors would determine the extent of preoperative testing that should be performed and if their results will affect perioperative management. Changes in management may include delay of surgery for prohibitive risks, delay of surgery for further medical management and optimization before surgery, coronary interventions such as stents placement, or if indicated, preoperative admission to the hospital for medical optimization, and monitoring.

Angina or dyspnea, which manifests with mild exertion may be a sign of significant CAD. Additional testing and monitoring should be considered as these patients are at high risk of perioperative cardiovascular events such as ventricular dysfunction, congestive heart failure, myocardial ischemia, or infarction. The patient with angina who is on strenuous exertion or stress test and does not manifest signs of left ventricular dysfunction can be medically managed with aspirin, beta blockers, nitrates, and statins. These patients can be considered optimized and no further cardiac testing is required.

In the event a patient has a history of prior MI, the timing between MI and surgery is crucial. Within 30 days of an MI, plaque and myocardial healing occurs. After this period, risk stratification is based on the presenting symptoms. Some patients will continue to have myocardium at risk; most ­patients however, were likely to have been reevaluated and their coronary stenosis revascularized if indicated or be on maximal medical therapy. The current practice of improved perioperative management, thrombolytics, and revascularization procedures have decreased the risk of reinfarction rate following NCS even if the prior MI was within 6 months.^8–10

Hypertension

Several large prospective studies have failed to establish mild to moderate hypertension as an independent predictor of postoperative cardiac complications, including arrhythmias, MI, heart failure, and cardiac death. Chronic hypertension may lead to increased risk of perioperative MI because these patients have a higher occurrence of CAD. However, in the Perioperative Ischemic Evaluation (POISE) trial of beta blocker therapy, the incidence of hypertension was 62% among 8351 patients and did not show hypertension as an independent predictor of postoperative stroke or death. Poorly controlled hypertension is often associated with hemodynamic fluctuations during anesthesia. The approach to the hypertensive patient relies on management strategies from nonsurgical literature where the recommendation being to continue antihypertensive agents in the perioperative period for optimal control of blood pressure. Blood pressure should be maintained at or near preoperative levels to reduce the risk of myocardial ischemia. In patients with severe hypertension, such as diastolic blood pressure higher than 110 mm Hg, the decision to delay surgery for optimization of blood pressure control should be weighed against the benefit or the urgency of surgery. A study by Hartle et al.¹¹ of 989 patients, compared the preoperative use of rapid-acting intravenous agents to lower blood pressure with a control group admitted for blood pressure control with 10-mg nifedipine intranasally. Control of blood pressure was rapidly achieved within a few hours and there was no statistical difference observed in postoperative complications between the two groups, suggesting that this subset of patients without significant cardiovascular comorbidities can proceed with surgery despite elevated blood pressure on the day of surgery.

Heart Failure

The clinical approach to the preoperative evaluation of the patient with heart failure should focus on risk assessment to determine whether to proceed with surgery, how to manage the patient intraoperatively, and postoperative care. This should be in agreement with the 2013 and 2014 ACC/AHA perioperative guidelines.¹² The initial step should take into consideration the following:

• • The assessment of functional status
  
• • Determining if patients are medically stable and optimized
  
• • Signs and symptoms of heart failure
  
• • Risk factors for developing heart failure
  
• • Comorbidities that may exacerbate heart failure in the perioperative period: underlying myocardial disease, CAD, valvular disease

Patients with heart failure have a higher risk of perioperative morbidity and mortality. Improvement in medical care has led patients to live longer with chronic diseases. Elderly patients who often lead a sedentary lifestyle because of chronic comorbidities and deconditioning, and have a higher incidence of heart failure. Symptoms of heart failure, such as fatigue and dyspnea, are not specific and may be confused with other chronic conditions, such as obesity and lung disease, which contribute to the delay in diagnosis and treatment. Careful preoperative evaluation is often required to differentiate heart failure from other debilitating comorbidities. For this reason, the elderly patient may present with an advanced stage of heart failure for preoperative evaluation. Elderly patients with heart failure have an increased risk of readmission compared with those with CAD admitted for the same diagnosis. A population-based analysis of 38,047 patients revealed a higher 30-day postoperative rate mortality for patients with nonischemic heart failure compared with other cardiac comorbidities, as shown in Table 30.3.

Although emphasis has been made on predicting cardiac perioperative risk in patients with CAD, patients with heart failure have a significantly higher risk of perioperative death than those with CAD. Certain risk factors and triggers should be identified as these contribute to the increased risk for major adverse events in the perioperative period. Identifying the severity of morbidities, such as CAD, hypertension, arrythmias, kidney disease, and diabetes in the patient with heart failure would influence the patient management in the perioperative period. These optimization measures may include early postoperative dialysis, preoperative beta blockers or antiarrhythmic medications, and optimal pain control to prevent hypertension.¹³ It is important to differentiate the etiology of the cardiomyopathy: dilated, obstructive, or ischemic. They have different perioperative management, which can affect influence postoperative morbidity. Dilated cardiomyopathy may require inotropic support; ischemic cardiomyopathy may develop further ischemia in the perioperative period. Obstructive cardiomyopathy has long been viewed as high risk for perioperative complications because of its high preload dependence with consequences of further dynamic obstruction, decreased cardiac output, and potential untoward results. Studies related to perioperative outcomes in patients with hypertrophic cardiomyopathy had small sample sizes, reflected different perioperative management, and have had mixed results.¹⁴ Most postoperative events were related to heart failure. Important independent risk factors for increased morbidity were major surgery and increased duration of surgery. Several studies show the 30-day cardiovascular event rate at 14% among heart failure patients with normal left ventricular function, 31% with left ventricular diastolic dysfunction, and up to 54% among patients with symptomatic heart failure. Risk classification remains a challenge because there is no model that can reliably predict who will experience a perioperative event opposed to those who will not across all levels of risk. Therefore the goals in the perioperative period, in addition to identifying the etiology and precipitating factors, should be to maintain stability, including symptomatic relief, maintain normal oxygenation, optimize volume status, and maintain organ perfusion.

The routine measurement of brain natriuretic peptide (BNP) is recommended in patients when the diagnosis is uncertain. BNP levels may also be helpful to identify disease severity, and in patients at increased risk for adverse outcome. Karthikeyan et al.¹⁵ evaluated nine studies, which included a total of 3281 patients, among whom 314 experienced one or more perioperative cardiovascular complications. The ­average proportion of patients with elevated BNP was 24.8%. All studies showed a statistically significant association between an elevated preoperative BNP level and various cardiovascular outcomes, such as a composite of cardiac death and nonfatal myocardial infarction or atrial fibrillation. The preoperative BNP measurement was an independent predictor of perioperative cardiovascular events in the first 30 days after NCS.

Valvular Heart Disease

The patient with valvular heart disease has significant risks for perioperative complications in the perioperative period. Suspected patients with valvular heart disease should undergo echocardiography evaluation for quantification of severity of stenosis or regurgitation, systolic function, and heart pressures if there has been no prior echocardiography performed within the past year or there is a change in clinical status since last evaluation. Patients should also undergo appropriate evaluation for the extent of the CAD. Over the past decades, improvements in anesthetic and surgical techniques have seen a significant decrease in 30-day perioperative morbidity and mortality from 13% to 2.1%. The mechanism of an acute perioperative event is likely associated with anesthetic agents and surgical stress leading to hemodynamic instability, decreased coronary perfusion with myocardial ischemia, arrythmias, heart failure, and possible death. Agarwal et al.¹⁶ evaluated the risk for perioperative complication in patients undergoing NCS with moderate aortic stenosis (AS) (valve area: 1.0–1.5 cm²) or severe AS (valve area: <1.0 cm²) from an echocardiographic database. Using propensity score analysis, they obtained four matched control patients without AS for each patient with AS undergoing NCS, matching 634 patients with AS undergoing NCS to 2536 controls. There were 244 patients with severe AS and 390 patients with moderate AS. The 30-day mortality was 2.1% for AS patients compared with 1.0% in non-AS controls (P = .036). Postoperative myocardial infarction was more frequent in patients with AS compared with controls (3.0% vs. 1.1%; P = .001). High-risk surgery, symptomatic severe AS, coexisting mitral regurgitation (MR), and preexisting coronary disease were significant predictors of primary outcome in patients with AS. Predictors of 30-day mortality in patients with moderate or severe AS are shown in Table 30.4.¹⁶

Patients who are candidates for aortic valve replacement (AVR) before lung resection surgery have several options available depending on their risk criteria. Options include AVR, transcatheter aortic valve replacement (TAVR), or percutaneous balloon dilation, as a bridge to definitive treatment after lung resection surgery. If they are considered high risk or ineligible, these patients may proceed with lung resection surgery with invasive monitoring for optimal hemodynamic monitoring. Simultaneously performed AVR and lung resection surgery on bypass have been carried out with success.

Patients with moderate to severe MR undergoing NCS had a higher perioperative mortality rate (1.7%) than those without MR (<1%). The 30-day primary outcomes, including postoperative death, MI, heart failure, and stroke, were 22.2% in those with MR compared with 16.4% without MR. Important predictors of morbidity in these patients were left ventricular ejection fraction less than 35%, ischemic etiology of MR, a history of diabetes mellitus, and a history of carotid endarterectomy. Perioperative management should include invasive hemodynamic monitoring and echocardiography and admission to the intensive care unit for postoperative management and care.¹⁷

Prosthetic Valves

An estimated 13% of patients with prosthetic heart valves will require noncardiac surgical procedure. These patients are at an increased risk of bleeding because of their anticoagulation therapy or for a thrombotic event from holding anticoagulation therapy in the perioperative period. The risk of a thrombotic event is higher in the immediate postoperative period and diminishes over time. In patients with an international normalizing ration (INR) maintained at 2.5 to 3.5, it is recommended to stop oral anticoagulation 5 days before surgery to let the INR decrease to a normal level. The INR should be tested on the day of surgery as individual responses are unpredictable and may vary. If the INR level is greater than 1.5 on the day of the procedure, oral administration of vitamin K, 1 to 2 mg, is an acceptable practice to lower the INR below 1.5 and proceed with surgery. Oral anticoagulation therapy may be resumed 12 to 24 hours after surgery. In cases of high risk for bleeding, the patient should be bridged with low-molecular-weight heparin (LMWH). Oral anticoagulation should be stopped 4 to 5 days before surgery and LMWH initiated. The last dose should be given 24 hours before surgery and may be resumed 48 to 72 hours after surgery when adequate hemostasis is secured. Different options for bridging therapies are available for outpatients and inpatients, depending on the clinical scenarios. The decision on how to bridge anticoagulation therapy with LMWH or unfractionated heparin should be decided with the clinical care management team following current guidelines. If the patient is at high risk for a perioperative thrombotic event, aspirin should be ­continued during the perioperative period. The decision should be based on the risk of bleeding versus the risk of a thrombotic event.¹⁸ Aspirin should be discontinued before spine, intracranial, or intraocular procedures.