To the Editor:

We read with interest the article by Glance et al.1  comparing the three cardiac risk calculators recommended by the American College of Cardiology/American Heart Association Perioperative Guidelines,2  and we commend the authors for their study using a large sample from the National Surgical Quality Improvement Program. We published a similar comparison3  using a much smaller sample of patients seen and evaluated in our preoperative clinic rather than information from an administrative database and came to somewhat different conclusions—that all three calculators were similar in their classification of low versus elevated risk and performed reasonably well when used as intended but not as well when used to predict different outcomes in different timeframes. Fleisher’s editorial4  touched on issues of varying complexity and completeness of risk factors and outcomes assessed by the calculators. We feel it is important to further highlight differences in patients included, risk factor definitions, and outcomes and their timeframes, which may explain differences in performance of these tools.

Although the authors did note differences in complications studied, they did not mention that the Revised Cardiac Risk Index5  only included patients aged 50 yr and older with an expected in-hospital length of stay of at least 2 days or more. The myocardial infarction or cardiac arrest6  and American College of Surgeons National Surgical Quality Improvement Program7  calculators included patients aged 16 yr and above and many more surgical procedures, including low-risk and ambulatory surgeries. The Revised Cardiac Risk Index included more cardiac complications as outcomes with heart failure being the main addition and only included in-hospital complications rather than at 30 days postoperative as in the National Surgical Quality Improvement Program calculators. The Revised Cardiac Risk Index routinely screened patients for postoperative myocardial infarction with electrocardiograms and creatine phosphokinase, whereas the National Surgical Quality Improvement Program database had different definitions of myocardial infarction, used the more sensitive troponin, but did not screen routinely. Because of these differences, direct valid comparisons cannot really be made. The Revised Cardiac Risk Index can be improved by the addition of an age variable as well as by changing from serum creatinine more than 2 mg/dl to creatinine clearance less than 30 ml/min.8  In another study, as age increased, complications and positive predictive value also increased within each Revised Cardiac Risk Index class.9  A recently published geriatric-sensitive Revised Cardiac Risk Index10  performed better on patients over age 65 than the original Revised Cardiac Risk Index. The addition of angina within the past 6 months to only a history of myocardial infarction improved National Surgical Quality Improvement Program predictors.11 

As noted by Glance et al., evaluation in real time allows the physician access to more information than the National Surgical Quality Improvement Program database. A complete history and physical can be performed, medical records including cardiac test results can be reviewed, medications are reviewed and changed as needed, and a better evaluation of the patient is likely compared with incomplete database records. Additionally, postoperative follow-up and surveillance may differ. Although we agree that there is wide variability in the performance of these calculators, much of it can be explained by the differences noted above. Because these risk predictions may alter physician behavior in terms of ordering further tests, it is important that these calculators are fully understood and used as intended. Further adjustments and comparison on a large scale in real time where more information can be obtained may help define whether one calculator is better than the others.

Competing Interests

The authors declare no competing interests.

References

1.
Glance
LG
,
Faden
E
,
Dutton
RP
,
Lustik
SJ
,
Li
Y
,
Eaton
MP
,
Dick
AW
:
Impact of the choice of risk model for identifying low-risk patients using the 2014 American College of Cardiology/American Heart Association Perioperative guidelines.
Anesthesiology
2018
;
129
:
889
900
2.
Fleisher
LA
,
Fleischmann
KE
,
Auerbach
AD
,
Barnason
SA
,
Beckman
JA
,
Bozkurt
B
,
Davila-Roman
VG
,
Gerhard-Herman
MD
,
Holly
TA
,
Kane
GC
,
Marine
JE
,
Nelson
MT
,
Spencer
CC
,
Thompson
A
,
Ting
HH
,
Uretsky
BF
,
Wijeysundera
DN
;
American College of Cardiology; American Heart Association
:
2014 ACC/AHA guideline on perioperative cardiovascular evaluation and management of patients undergoing noncardiac surgery: A report of the American College of Cardiology/American Heart Association Task Force on practice guidelines.
J Am Coll Cardiol
2014
;
64
:
e77
137
3.
Cohn
SL
,
Fernandez Ros
N
:
Comparison of 4 cardiac risk calculators in predicting postoperative cardiac complications after noncardiac operations.
Am J Cardiol
2018
;
121
:
125
30
4.
Fleisher
LA
:
Preoperative cardiac evaluation before noncardiac surgery: Reverend Bayes’s risk indices and optimal variables.
Anesthesiology
2018
;
129
:
867
8
5.
Lee
TH
,
Marcantonio
ER
,
Mangione
CM
,
Thomas
EJ
,
Polanczyk
CA
,
Cook
EF
,
Sugarbaker
DJ
,
Donaldson
MC
,
Poss
R
,
Ho
KK
,
Ludwig
LE
,
Pedan
A
,
Goldman
L
:
Derivation and prospective validation of a simple index for prediction of cardiac risk of major noncardiac surgery.
Circulation
1999
;
100
:
1043
9
6.
Gupta
PK
,
Gupta
H
,
Sundaram
A
,
Kaushik
M
,
Fang
X
,
Miller
WJ
,
Esterbrooks
DJ
,
Hunter
CB
,
Pipinos
II
,
Johanning
JM
,
Lynch
TG
,
Forse
RA
,
Mohiuddin
SM
,
Mooss
AN
:
Development and validation of a risk calculator for prediction of cardiac risk after surgery.
Circulation
2011
;
124
:
381
7
7.
Bilimoria
KY
,
Liu
Y
,
Paruch
JL
,
Zhou
L
,
Kmiecik
TE
,
Ko
CY
,
Cohen
ME
:
Development and evaluation of the universal ACS NSQIP surgical risk calculator: A decision aid and informed consent tool for patients and surgeons.
J Am Coll Surg
2013
;
217
:
833
42.e13
8.
Davis
C
,
Tait
G
,
Carroll
J
,
Wijeysundera
DN
,
Beattie
WS
:
The Revised Cardiac Risk Index in the new millennium: A single-centre prospective cohort re-evaluation of the original variables in 9,519 consecutive elective surgical patients.
Can J Anaesth
2013
;
60
:
855
63
9.
Andersson
C
,
Wissenberg
M
,
Jørgensen
ME
,
Hlatky
MA
,
Mérie
C
,
Jensen
PF
,
Gislason
GH
,
Køber
L
,
Torp-Pedersen
C
:
Age-specific performance of the revised cardiac risk index for predicting cardiovascular risk in elective noncardiac surgery.
Circ Cardiovasc Qual Outcomes
2015
;
8
:
103
8
10.
Alrezk
R
,
Jackson
N
,
Al Rezk
M
,
Elashoff
R
,
Weintraub
N
,
Elashoff
D
,
Fonarow
GC
:
Derivation and validation of a geriatric-sensitive perioperative cardiac risk index.
J Am Heart Assoc
2017
;
6
:
e006648
11.
Pandey
A
,
Sood
A
,
Sammon
JD
,
Abdollah
F
,
Gupta
E
,
Golwala
H
,
Bardia
A
,
Kibel
AS
,
Menon
M
,
Trinh
QD
:
Effect of preoperative angina pectoris on cardiac outcomes in patients with previous myocardial infarction undergoing major noncardiac surgery (data from ACS-NSQIP).
Am J Cardiol
2015
;
115
:
1080
4