Surgical risks

Risk of myocardial infarction (MI)

From a perioperative cardiac complication standpoint, the risk of myocardial infarction and cardiac arrest (MICA) is of greatest concern. The risk is obviously highest in the setting of an acute coronary syndrome, and revascularization should be performed in appropriate patients followed by delay in any nonemergent surgery. Timing of cancer surgery would depend on the temporal urgency of resection to decrease local and metastatic spread coupled with appropriate timing for consideration of interrupting dual antiplatelet therapy (impacted by factors such as stent type and size, lesion location, number of stents). The general guidance, based predominantly on the recommended length of dual antiplatelet therapy, is to delay surgery by 14 days after balloon angioplasty (rarely indicated), 30 days after bare metal stent and ideally 6 months after drug-eluting stent (DES), although 3 months may be acceptable if the risk of delaying surgery is greater than risk of stent thrombosis. The specific timelines are changing with updated data gathered in patients with newer DES designs. For patients who have undergone coronary artery bypass grafting (CABG), timing of noncardiac surgery should be delayed for a minimum of 4 to 6 weeks to allow for sternal healing. For patients who have had an MI in the absence of intervention, the current 2014 American College of Cardiology/American Heart Association (ACC/AHA) guidelines recommend to delay noncardiac surgery until the risk of MI and mortality has exponentially decreased, commonly at least 60 days. Patients who undergo revascularization for MI fare better (50% lower risk); however, antiplatelet therapy considerations pertain to percutaneous coronary intervention (PCI) and the above outlined aspects to bypass surgery.

Patients who have a higher perioperative risk (e.g., surgery type with >1% risk of major adverse cardiac events or based on risk scores such as the revised cardiac risk index or RCRI ) with good functional capacity should proceed to surgery. If functional capacity is poor or unknown, noninvasive coronary assessment (e.g., stress echocardiography, radionuclide stress myocardial perfusion imaging, computed topography coronary angiography) should be performed if it will change perioperative management ( Fig. 6.1 ). Indeed, it is a major message of the ACC/AHA guidelines on perioperative risk assessment to consider noninvasive evaluation for coronary arterial disease only if the results would change management. In addition to the RCRI score, newer risk scores include the National Surgical Quality Improvement Program (NSQIP) Surgical Risk calculator and the NSQIP MICA risk calculator ( Table 6.1 ). ^,

Risk of heart failure decompensation

Whereas symptomatic heart failure has the highest cardiovascular risk for patients undergoing surgery in general, asymptomatic left ventricular (LV) dysfunction also carries an increased risk of cardiovascular morbidity and mortality compared with patients without heart failure or abnormal LV function. In a large retrospective study of mostly male veterans undergoing a variety of surgical procedures, for example, 90-day mortality was 1.2%, 4.8%, and 10.1% for patients without heart failure, asymptomatic systolic dysfunction, or symptomatic heart failure, respectively. Patients with symptomatic heart failure (with preserved or reduced ejection fraction [EF]) and patients with asymptomatic LV dysfunction should be assessed by a cardiologist prior to surgery for evaluation and medical optimization with guideline-directed therapies. Assessment of LV function prior to surgery should be performed particularly in any patient who has been exposed to potentially cardiotoxic therapies including (but not limited to) anthracyclines, human epidermal growth factor receptor (her-2) antagonists, certain vascular endothelial growth factor inhibitors and tyrosine kinase inhibitors, and immunotherapies (see Central Illustration). While strain parameters (e.g., derived by speckle tracking echocardiography) have been shown to predict cardiotoxicity with cancer therapeutics, their value to assess surgical risks of patients with cancer has not yet been defined. Finally, biomarkers such as brain natriuretic peptide (BNP) and NT-proBNP can also help stratify the cardiovascular risk of patients undergoing noncardiac surgery. A NT-BNP greater than 300 ng/L or a BNP greater than 92 mg/L is associated with a four-fold increase in the postoperative risk of death or nonfatal MI.

Risk of cerebrovascular events (CVE)

Patients with cancer are at increased risk of atrial fibrillation (AF) and this risk increases with surgery. Owing in part to the increased hypercoaguable state, patients with many types of cancer are also at increased risk for CVE independent of AF. AF occurs in approximately 12.6% of patients with cancer who are undergoing lung resection and it is also common in patients with cancer undergoing colectomy or esophageal resection. Elevated perioperative NT-BNP is associated with an increased risk of AF after lung cancer resection. Although AF confers a five-fold increased risk of CVE in the general population, the risk of CVE in those with cancer with post operative AF is not well studied nor is the optimal treatment approach. No evidence supports the use of routine preoperative carotid imaging prior to surgery.

Risk of venous thromboembolic events (VTE)

The risk of venous thromboembolism is markedly elevated in patients with cancer. Those undergoing surgery have two times higher rates of postoperative VTE than do patients without cancer. In addition to patient characteristics, such as advanced age, morbid obesity, and prolonged hospitalization, cancer type is a major risk factor for VTE in those patients undergoing surgery. For example, the 30-day incidence of VTE after breast cancer surgery is very low (~0.30%); however, the VTE incidence for patients undergoing esophagectomy, cystectomy, and pancreatectomy is very high (~7.3%, 4.9%, and 3.4%, respectively). Patients should have prophylaxis for VTE administered postoperatively as soon as feasible, from a postoperative bleeding perspective.