Cardiac Disease and Anesthetic Risk Assessment
Cardiovascular disease is one of the leading causes of death worldwide and is the #1 cause of death in the US. Cardiac complications in patients undergoing non-cardiac surgery is a major cause of morbidity and mortality in the perioperative timeframe. This risk can be as high as almost 10% in patients with multiple risk factors. As anesthesiologists, it is our role to make sure that we reduce this risk as much as possible. This starts with a preoperative evaluation of each surgical patient and determining if they are safe to proceed for their given operation.
One of the first questions we ask is what is the urgency of this operation? If this is an emergent surgery that life or limb depends on, then there is nothing more to do than proceed to the operation with caution. If the surgery is non-emergent, you have time to assess the patients risk of having a Major Adverse Cardiac Event (MACE).
One of the tools that we use to risk strategy a patient is the Revised Cardiac Risk Index, which has 6 independent patient factors that determine the likelihood of a patient having a major cardiac event in the perioperative time:
High Risk Surgery
History of Ischemic Heart Disease
History of Congestive Heart Failure
History of Cerebrovascular Disease
Diabetes Mellitus on Insulin
Preoperative Creatinine > 2.0 mg/dL
When assessing the risk of a surgery, it can fall into three categories:
High Risk
Aortic and other major vascular procedures
Laparoscopic colectomy and end-ileostomy
Breast reconstruction with a free flap
Open cholecystectomy
Open hernia repair
Whipple Procedure
2. Intermediate Risk
Intraperitoneal and intrathoracic operations
Carotid endarterectomies
Head/neck operations
Prostate operations
Total hip replacement
3. Low Risk
Endoscopic procedures
Superficial procedures
Cataracts operation
Simple/partial mastectomy
Ambulatory surgery
If a patient has a higher than 1% risk of having a MACE, you must then assess their functional status. Functional status is measured by using metabolic equivalents (METs). One MET equals the oxygen consumption of a person at rest (about 3-5 ml/kg/min). A functional status of 4 METs is considered the minimum requirement for a patient to safely undergo general anesthesia. The best way to assess for this is by asking the patient is they can climb a flight of stairs without any chest pain or shortness of breath. If they do not regularly use stairs, I will often ask them if they can perform basic household chores like washing the dishes or cleaning up around the house without exhaustion. If they have no problems with these tasks, you are quite safe to proceed with the operation and general anesthesia. If they are unable to climb a flight of stair and are limited in their daily activities by shortness of breath or chest pain, you want to investigate further.
There are some active cardiac conditions to look out for that you would want to optimize prior to having the patient undergo anesthesia. These include:
unstable coronary syndrome (ie. Angina)
Decompensated Heart Failure
Significant arrhythmias (ie. High-grade AV block, SVTs, symptomatic bradycardia)
Severe valve disease (ie. AS with meanPG > 40 mmHg or AVA < 1, symptomatic MS)
If the patient is not suffering from any of these conditions but is still high risk for surgery, then you should consider noninvasive testing if it will change your management. This testing is typically pointing at a dobutamine stress test. If your patient is undergoing a high-risk surgery with potential for large hemodynamic variability and you are concerned about ischemic/coronary heart disease, it is not unreasonable to investigate this further prior to having the patient undergo the surgery. Many times, this decision making is made collaboratively with the surgical and medicine team (especially if the patient is chronically followed by a cardiologist). The textbook answer is if this testing will affect your anesthetic management, then you should acquire the test. Another example would be a patient with valvular disease who has new symptoms since their most recent transesophageal echo. This would be an ideal time to perform a new echo to evaluate for progression of their valvular disease.
