CME Module 9: Peri-Operative Cardiac Risk Reduction Next >

 

The Problem:

Cardiovascular complications continue to be a major cause of perioperative morbidity and mortality in patients undergoing noncardiac surgery. Although the last decade has seen the introduction of pre-operative assessment strategies, the AHA guidelines, new drugs, and minimally invasive surgical techniques, there is presently no evidence that we have been able to change our postoperative mortality rates. In fact, the peri-operative mortality rates are increasing in women. In a recent review of over 60,000 hip replacements, Lie et al found that death was 4 times more common on the first day after orthopedic surgery than the death rate in an age and risk adjusted population not having surgery(1). More than 50% of these deaths were a direct result of a cardiovascular insult. Furthermore, patients who survive a postoperative MI are twice as likely to die in the next 2 years compared to patients having uncomplicated surgery(2).

In addition to the obvious detrimental effects of a perioperative cardiac event on the health of the patient, there are also added financial costs. For example, the costs of a postoperative MI are 50% higher than uncomplicated surgery. In the event of a postoperative cardiac related death, the hospital costs double.(3)

Who can safely have surgery?


Interpretation of the 2007ACC/AHA guideline

Perioperative risk is a function of both the patient characteristics and the type of surgery. Obviously, in some cases the urgency of surgery supersedes the need for risk evaluation. However, for patients undergoing elective surgery the delineation of risk begins with a good history and physical examination. The 2007 ACC/AHA guidelines on Perioperative Cardiovascular Risk Evaluation and Care for Noncardiac Surgery emphasizes that patients with “active” cardiac disease need to be treated according to the ACC/AHA guidelines for the care of patients with coronary artery disease (47). These active conditions include unstable coronary syndromes, decompensated heart failure, significant arrhythmias and severe valvular disease, namely severe aortic stenosis or symptomatic mitral stenosis (47).  In essence, the guidelines suggest that NO ELECTIVE surgery (at any risk level) should proceed until the heart disease is under control. That is, it is important to understand that these guidelines do not imply that patients with active cardiac disease can proceed to low risk surgery but rather need to undergo evaluation and treatment as per the ACC/AHA treatment recommendations.

On history, details of cardiac risk factors and changes in effort tolerance must be sought and cannot be underestimated. Patients who cannot achieve a maximal effort tolerance of 4 METS (equivalent to walking up a flight of stairs) are at an elevated risk of having a perioperative cardiac event (4). The present guidelines suggest that it is safe to proceed with surgery only if patients, after a good history, have adequate effort tolerance and no symptoms of ischemic like pain. Otherwise, all patients with coronary disease require treatment, if they have symptoms and, once treated, should proceed to surgery on ALL medications that are maintaining them symptoms free.

There have been several preoperative assessment strategies published. These strategies are not widely employed in clinical practice, most being too cumbersome or hard to remember. The Revised Cardiac Risk Index (RCRI) (5), (see below) is as accurate as any other index, is the easiest to remember, has been employed in clinical trials to stratify patient risk, and is presently utilized in the 2007 ACC/AHA guidelines to stratify patients. These guidelines suggest that patients who do not have good effort tolerance can proceed to surgery, provided they have no risk factors. On the other hand, any patient for elective intermediate or high risk surgery who does have RCRI risk factors, should be tested “if it will change treatment”. In essence, if you identify active ischemia, it should be controlled before proceeding to surgery.

Revised Cardiac Risk Index (RCRI)

  • High risk type of surgery
  • Ischemic heart disease
  • History of CHF
  • History of cerebrovascular disease
  • Insulin therapy for diabetes
  • Preoperative serum creatinine >2.0mg/dl          

Classification of patients on the RCRI
(major cardiac complication rate)

Class 1 – no risk factors (0.5%)*
Class 2 – presence of 1 risk factor (1%)*
Class 3 – presence of 2 risk factors (6%)*
Class 4 – presence of ≥ 3 risk factors (10%)*
* (risk of sustaining a major cardiac
complication derived by averaging
the derivation and the validation cohorts)


The statement in the 2007 guidelines that patients who have 1-2 RCRI risk can proceed to surgery with HR control stems from DECREASE 2 (46).  In that trial, patients were randomized to either preoperative consult or no consult, but were all started on beta blockers. The result of the trial showed no difference in the incidence of postoperative MI, regardless of whether or not they had a consult. In contrast, the POISE trial showed unequivocally that starting patients on beta blockers on the day of surgery, without testing, resulted in fewer MI’s but increased both strokes and mortality! Until there is more evidence, these results would suggest that all patients with poor effort tolerance, who also have 1 or more RCRI risk factors should be tested for inducible ischemia.
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