SCA Meeting New Orleans
EACTA CARDIAC RISK ASSESSMENT
Perioperative risk stratification in cardiac surgery patients – Marco Ranucci, MD
There are currently a number of different tools to stratify the mortality risk after cardiac
operations. They all provide an estimate of the mortality risk, but with different windows of
observation: Some are limited to in-hospital mortality (EuroSCORE II), others extend the
observation to 30 days after surgery (ACEF score), none addresses outcome after 90 days
or longer.
Despite this relatively huge amount of possible tools, risk stratification is still a matter of
controversy. The main points of debate are:
1. Absence of potential risk factors
A number of risk factors that are particularly frequent in the elderly patient population is still
lacking in all the existing risk score.
Preoperative anemia is associated with an increased morbidity and mortality risk following
cardiac surgery1-6. In the elderly patients, who are more frequently affected by different
degrees of anemia, this factor plays an even more important role in deteriorating the
outcome.
Liver dysfunction is another factor not included in the existing risk scores, which is
associated with a mortality rate up to 50% in the most severe cases7,8.
Additional risk factors that are particularly frequent in the elderly population and that are not
included in the existing risk scores are atrial fibrillation, poor exercise tolerance, and
neuropshychological conditions.
Additionally, some conditions, like chronic obstructive pulmonary disease (COPD) should
be better defined in terms of severity (i.e. oxygen-dependency).
2. The window of observation
The most important criticism for the existing risk stratification models is the very narrow
window of observation after surgery. STS-PROM and ACEF score limit the observation to
30-days after surgery. The EuroSCORE II is even worse, since the mortality risk prediction
is limited to in-hospital mortality. Data from the development series of the EuroSCORE II
however clearly demonstrate that if the window of observation is extended to 90 days, the
crude mortality increases of as much as an additional 1.5%9.
In the elderly patients, and especially for octogenarians, the problem of the window of
observation is particularly important. As a matter of fact, in this segment of population, the
expected mortality rate after surgery may conflict with the expected mortality rate without
surgery, i.e. with alternative treatments (medical or other less invasive treatments)..
This concept has been very recently highlighted by the group of Nashef, who introduced the
concept of the “Time Until Treatment Equipoise” (TUTE)10. The TUTE concept highlights the
ratio between the expected survival rate after surgery or with medical treatment. Figure 5
shows some examples of this approach.
3. The concept of “successful” procedure
The great majority of the risk models consider either the “rough outcome” of mortality, or
major complications during the hospital stay (acute kidney failure, stroke, and others).
However, in the context of the elderly patient, a great attention should be deserved to the
concept of quality of life (QOL) after the surgical procedure. Elderly patients are particularly
prone to neurologic complications after cardiac and major vascular surgery, and the existing
risk models for stroke and other neurologic sequelae consider age as the main risk factor 11.
These neurological sequelae are the main determinant of a poor quality of life after surgery.
Another factor which results in a deterioration of the QOL is kidney failure requiring
permanent renal replacement therapy, that again is much more frequent in elderly
patients12,13. All together, a number of additional factors may result in a QOL that is worse
after surgery than before surgery, including the need for permanent pacemaker, the
permanent loss of attention and memory, and a global inability to attend the daily life tasks,
with the need for external support.
Therefore, the concept of “successful surgical treatment” should be defined in terms of
survival with an improved QOL after an adequate window of observation (one year after
surgery).
References
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Postoperative Mortality and Adverse Cardiac Events in Elderly Patients Undergoing
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is a powerful predictor of adverse outcomes in coronary artery bypass graft surgery:
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8. Lopez-Delgado JC, Esteve F, Javierre C, Perez X, Torrado H, Carrio ML,
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index for patients undergoing coronary artery bypass graft surgery. Multicenter
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Suppl):II74-80.
12. Thakar CV, Arrigain S, Worley S, Yared JP, Paganini EP. A clinical score to predict
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13. Mehta RH, Grab JD, O’Brien SM, Bridges CR, Gammie JS, Haan C, Ferguson TB,
Peterson ED. Bedside tool for predicting the risk of postoperative dialysis in patients
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