Preoperative Assessment of the Patient with Heart Disease Case File
Lydia Conlay, MD, PhD, MBA, Julia Pollock, MD, Mary Ann Vann, MD, Sheela Pai, MD, Eugene C. Toy, MD
Case 16
A 54-year-old man presents with new-onset “frequent indigestion and diarrhea” over the past 3 months, which his primary care physician ascribes to cholelithiasis. He is scheduled for a laparoscopic cholecystectomy. The surgeon has requested general anesthesia, and an evaluation in the Anesthesia Outpatient Screening Clinic. He has not ordered any laboratory or other tests, but has written on the preoperative tests/orders sheet as “per anesthesia.” A postoperative admission to the hospital is planned.
The patient’s medical history is remarkable for a hospital admission for 3 days 2 years previously, to rule out a possible myocardial infarction (MI). He was discharged with a diagnosis of “possible non–Q-wave MI.” His history is also notable for hypertension, treated with lisinopril hydrochlorothiazide and beta blockers. He has a sedentary lifestyle, but can easily walk up two flights of stairs.
The patient has no history of complications with previous anesthetics or a family history of problems with anesthesia. He has no allergies to medications and does not consume alcohol. He smoked 2 packs of cigarettes per day since age 18, but had quit smoking 2 years ago.
The patient’s yearly chest x-ray and ECGs have been “normal” or “unchanged.” He missed his yearly ECG and dobutamine stress test 6 months ago, but the two previous studies were normal. The hematological, liver, and kidney function tests were normal as well.
On examination, the patient weighs 89 kg and is 5 ft, 11 in tall. His vital signs are: BP 150/90, HR 90 and regular, respiratory rate 20, and a temperature of 37°C. His neck appears normal and is mobile, he opens his mouth without difficulty, and with his head extended and tongue protruding, his uvula is completely visible. His pulmonary and cardiac examinations are normal.
Laboratory tests ordered by your partner include: Hct 41, WBC 9600, platelets 320,000, Na+ 138, K+ 3.4, HCO3 28, BUN 18, creatinine 1.4, and blood glucose 142. His chest x-ray (CXR) showed “no airspace disease with borderline cardiomegaly,” and his ECG, “NSR, rate 86, occasional PACs, borderline LVH, non-specific ST-T changes, unchanged from prior studies.”
➤ What is the appropriate preoperative management of this patient?
➤ Is any further testing needed, and if so, what?
ANSWER TO CASE 16:
Preoperative Assessment of the Patient with Heart Disease
Summary: A 54-year-old male patient with cholelithiasis is scheduled for an elective cholecystectomy. He has a history of hypertension, tobacco use, and current indigestion with normal exercise capacity and a history of MI 2 years ago.
➤ Appropriate preoperative management: Continue the lisenopril on the morning of surgery.
➤ Further testing: This is an elective case, in a patient with good functional capacity, without evidence of myocardium at risk, and who is undergoing a low-risk surgical procedure. No further testing is indicated.
ANALYSIS
Objectives
1. Understand the rationale for the 2007 revision of the guidelines for cardiac evaluation before non-cardiac surgery by the American College of Cardiology/American Heart Association (ACC/AHA).
2. Become familiar with the relationship between the level of complexity of the surgical procedure and the level of preoperative testing in the patient with heart disease.
3. Understand the method for and advantages of preoperative cardiac risk stratification for patients undergoing non-cardiac surgical procedures.
Considerations
This is an elective case, so the patient’s clinical predictors, such as exercise capacity, and the level of surgical risk guide further diagnostic and therapeutic interventions. His MI was more than 7 days ago, and although he missed the most recently-scheduled stress test, one had been performed following his MI which did not indicate any myocardium at risk, and the patient’s functional capacity is good. Inguinal herniorrhaphy is a low-risk procedure. Since this patient is at low risk for a cardiac event and is undergoing a low-risk surgical procedure, he can proceed to surgery without further testing. He is counseled to continue his lisinopril, and to take it as usual on the morning of surgery.
APPROACH TO
Preoperative Assessment of the Patient with Possible CAD
CLINICAL APPROACH
Morbidity and mortality from cardiac complications are the most common significant adverse events in the perioperative period. Up to 1% of the 100 million adults having non-cardiac surgery each year will be affected, and of those affected, one in four will die. The goal of any preoperative examination is to lower the risk in the preoperative period by identifying patients with modifiable conditions, and optimizing these conditions prior to surgery. A natural part of this process includes identifying patients with a high risk for perioperative cardiac events.
The 2007 revision of the guidelines for cardiac evaluation before non-cardiac surgery by the American College of Cardiology/American Heart Association (ACC/AHA) reduced the recommendations for preoperative noninvasive stress testing and revascularization. This altered approach was driven by the recognition that unpredictable coronary plaque rupture, of even minor lesions and thrombi cause up to 50% of fatal MIs perioperatively. Revascularization, typically recommended for the more critical stenosis, does not prevent plaque rupture.
The ACC/AHA guidelines are organized in a stepwise approach. Management is determined by the first recommendation that applies to a particular patient. There is no need to progress through the entire algorithm.
Step 1 considers the urgency of the surgery. If emergency surgery precludes further cardiac assessment, the focus of patient management shifts to perioperative surveillance (eg, serial ECGs, enzymes, monitoring), and the reduction of risk (eg, beta blockers with strict control of heart rate, statins, pain management). Clinical predictors, exercise capacity, and the level of surgical risk guide further diagnostic and therapeutic interventions.
Step 2 considers an active cardiac condition. An acute MI, unstable or severe angina, decompensated heart failure, severe valvular disease (eg, severe aortic stenosis), or significant arrhythmias (eg, ventricular tachycardia or atrial fibrillation with a rapid rate) warrant the postponement for all except life-saving emergency surgery. More recent evidence suggests that an acute MI, occurring within the past 7 days, warrants postponing elective surgeries. An MI within the past 8 to 30 days, and with evidence of myocardium at risk (indicated by persistent symptoms or the results of stress testing) represents a high-risk condition. If the recent MI is not accompanied by myocardium at risk, the patient’s risk is simply equivalent to that of coronary artery disease any other time.
Step 3 considers the risk of the surgical procedure. Low-risk surgical procedures include endoscopic procedures, superficial procedures, cataract surgery, breast surgery, and most ambulatory surgical procedures. These procedures carry such low risk of an adverse cardiac-event risk (generally < 1%) that even patients at high cardiac risk, provided that they do not have any active cardiac conditions, should proceed directly to surgery without further testing.
Intermediate-risk surgery (1%-5% risk of cardiac complications) includes orthopedic, most intra-abdominal, and intrathoracic procedures. Patients who need vascular surgery are most likely to benefit from further testing.
Step 4 assesses the patient’s functional capacity. Asymptomatic patients with heart disease, who have an average exercise capacity (can walk up two flights of stairs or four blocks) can proceed to surgery.
Step 5 considers patients with poor or indeterminate functional capacity scheduled for vascular, intermediate-, or high-risk procedures. This is the last and most complex step. Clinical predictors for cardiac risk were derived from the revised cardiac risk index, identifying ischemic heart disease, heart failure, cerebrovascular disease, diabetes, and renal insufficiency as important patient comorbidities. The number of these clinical predictors alters the recommendations for and likely benefit from cardiac testing. Patients without these clinical predictors may proceed to surgery without further testing.
The ACC/AHA guidelines recommend further testing only “if it will change management.” Patients with three or more clinical risk factors, and who need vascular surgery are most likely to benefit from further testing. Patients with one to two clinical predictor(s), and who need intermediate-risk surgery (1%-5% risk of cardiac complications, including procedures such as orthopedic, intra-abdominal and intrathoracic procedures) or vascular surgery can proceed to surgery with heart rate control. Or, they should be scheduled to undergo noninvasive testing if it will change management. The guidelines specifically state, “there are insufficient data to determine the best strategy.” Factors to consider are the urgency of the non-cardiac surgery (eg, patients with cancer), the life-expectancy of the individual, and the potential longterm benefits of medical management versus revascularization.
Lastly, the general risk factors for CAD (eg, smoking, family history, hypercholesterolemia, age, and hypertension) have not been shown to predict perioperative cardiac morbidity.
Comprehension Questions
16.1. During the preoperative cardiac assessment for elective surgical procedures, which pieces of information are essential to determine if further testing is warranted?
A. An ECG
B. A dobutamine stress test
C. Information regarding the patient’s functional (exercise) capacity
D. A chest x-ray
16.2. Which of the following warrants additional preoperative noninvasive stress testing and possible revascularization prior to non-cardiac surgery?
A. A 45-year-old man with a history of diabetes and poor exercise tolerance, who is scheduled for a colon resection for a mass.
B. A 74-year-old man with chronic, stable angina scheduled for a total knee replacement.
C. A 65-year-old woman with a history of hypertension, chronic atrial fibrillation with a ventricular heart rate of 75 beats per minute scheduled for a carpal tunnel repair.
D. A 58-year-old man with a history of hypertension and a left bundlebranch block undergoing a total knee replacement.
16.3. Which all of the following comorbidities would warrant postponement of an elective operation?
A. Acute MI within the last 30 days
B. Renal failure
C. Heart failure
D. Unstable arrhythmias
ANSWERS
16.1. C. According to the AHA/ACC guidelines, information regarding the patient’s functional (exercise) capacity, understanding whether the patient has any evidence (or absence) of an unstable cardiac condition, and knowledge of the magnitude of the type of surgery planned for the patient. An ECG is not indicated in patients under 50 years of age (60 in some settings), and a dobutamine stress test is indicated if there is a suspicion of myocardium at risk. Although a chest x-ray can be useful to determine a patient’s heart size, it is not otherwise helpful in determining whether further cardiac testing is warranted.
16.2. A. This patient is undergoing an intermediate-risk procedure, and has one clinical predictor (diabetes). Since further testing may elucidate a cause for his poor exercise tolerance, additional testing is indicated. The patients in answer B has one clinical predictor (ischemic heart disease), and is scheduled for an intermediate-risk procedure. His condition is stable, and he has good functional capacity. No further testing is indicated. The patient in answer C has no clinical predictors and is scheduled for a low-risk procedure. She does not need further testing. The patient in answer D has no risk factors and is undergoing an intermediate-risk procedure. So no further testing is warranted.
16.3. D. D, an unstable arrhythmia, is an active cardiac condition and warrants postponement of all except life-saving surgeries. A, an MI within the past 8 to 30 days, and with the evidence of myocardium at risk (indicated by persistent symptoms or the results of stress testing) represents a high-risk condition, but does not necessarily warrant postponement of surgery. If the recent MI is not accompanied by myocardium at risk, the patient’s risk is simply equivalent to that of any other patient with coronary artery disease any other time. Answers B and C, renal failure and heart failure, are clinical predictors of cardiac risk but do not warrant postponing elective surgery. Other clinical predictors include ischemic heart disease.
Clinical Pearls
➤ Cardiac complications are the leading cause of perioperative morbidity and mortality in the perioperative setting.
➤ Major clinical risk factors include acute coronary syndromes, decompensated heart failure, clinically significant arrhythmias, and severe valvular disease.
➤ Intermediate-risk predictors include ischemic heart disease, compensated or prior heart failure, cerebrovascular disease, diabetes mellitus that requires insulin therapy, and renal insufficiency (serum creatinine level > 2 mg/dL).
➤ Exercise capacity remains an important determinant of perioperative risk.
➤ Elective major vascular surgery remains the type of surgery with the highest associated risk.
References
Fleisher LA, Beckman JA, Brown KA, et al. ACC/AHA 2007 Guidelines on Perioperative Cardiovascular Evaluation and Care for Non-cardiac Surgery. J Am Coll Cardiol. 2007;50:e159-241.
Lee TH, Marcantonio ER, Mangione CM, et al. Derivation and prospective validation of a simple index for prediction of cardiac risk of major non-cardiac surgery. Circulation. 1999;100:1043-1049.
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