By Zafir Hawa, MD
“Is it worth the risk?” Internists and cardiologists hear this question all the time regarding the perioperative risk our patients may face when they need surgery. Fortunately the AmericanCollege of Cardiology (ACC) developed an excellent set of guidelines to help us navigate this topic. These guidelines are solidly based on the Revised Cardiac Risk Index, a study published by Thomas Lee MD in 1999.
One Page Guide to the Revised Cardiac Risk Index
To make it easier for physicians to understand these guidelines, Northland Cardiology developed a handy, one-page digest of the Revised Cardiac Risk Index. We use it routinely to assess perioperative risk. We will make it available to any physician who requests it.
The ACC Guidelines
The ACC divides surgeries into two categories: emergent and non-emergent. Since emergent surgeries are otherwise life threatening, the ACC recommends proceeding without doing much of a workup aside from taking a medical history and performing a physical exam. The ACC guidelines predominantly focus on elective surgery in patients who are either at risk for heart disease or already have a history of it. The ACC identifies 6 factors that determine perioperative risk. These factors include:
The ACC recommends that patients with active cardiac conditions should undergo further evaluation and treatment before having non-cardiac surgery. Conditions that generally require cancelling non-cardiac related surgeries include:
A Key Evaluative Factor: Physical Activity Level
The ACC recommends using the patient’s physical activity level as a primary evaluative factor in determining perioperative risk. Patients who can exercise above a certain threshold without having any symptoms suggestive of angina, likely do not need any further testing. These patients should be able to handle whatever elective surgery is in question.
The ACC determined this threshold to be greater than 4 METs and developed a chart to indicate what activities correspond to this level. For example, activities like doing work around the house, climbing up a flight of stairs or walking on level ground at a brisk pace would all meet the 4 METs threshold. Patients who meet this threshold typically do not need a stress test prior to surgery.
The analysis is a bit more complex for patients who have a functional capacity less than 4 METs. The ACC recommends noninvasive testing for patients who have three or more clinical risk factors or are undergoing a high risk surgery such as vascular surgery, or when these tests will alter management. Unfortunately the role of preoperative revascularization of obstructive CAD is limited in its ability to prevent perioperative cardiac events and will usually lead to a delay the surgery.
About Dr. Zafir Hawa
Zafir Hawa, MD grew up in Bombay, India. He received his medical degree from the University of Bombay in 1992 and completed his internship and residency in internal medicine at the University of North Dakota. He also completed two fellowships - one in critical care at the University of Pittsburgh and one in cardiology and interventional cardiology at Temple University-Western Pennsylvania Hospital. Dr. Hawa is a Fellow in the American College of Cardiology and the Society of Cardiovascular Angiography and Interventions. He is board certified in Cardiovascular Disease, Interventional Cardiovascular Disease and Nuclear Cardiology. Dr. Hawa practices with Northland Cardiology.