Home > CT coronary angiography, Journal Club > Journal Club 6 May 2015

Journal Club 6 May 2015

Paper

Prognostic capabilities of coronary computed tomographic
angiography before non-cardiac surgery: prospective cohort study

Presenter

KK

Summary

Objectives

To determine if coronary computed tomographic
angiography enhances prediction of perioperative risk
in patients before non-cardiac surgery and to assess
the preoperative coronary anatomy in patients who
experience a myocardial infarction after non-cardiac
surgery.

Design

Prospective cohort study.
Setting
12 centers in eight countries.
Participants
955 patients with, or at risk of, atherosclerotic disease
who underwent non-cardiac surgery.

Interventions

Coronary computed tomographic angiography was
performed preoperatively; clinicians were blinded to
the results unless left main disease was suspected.
Results were classified as normal, non-obstructive
(<50% stenosis), obstructive (one or two vessels with
≥50% stenosis), or extensive obstructive (≥50%
stenosis in two vessels including the proximal left
anterior descending artery, three vessels, or left main).

Main outcome measure

Composite of cardiovascular death and non-fatal
myocardial infarction within 30 days after surgery
(primary outcome). This was the dependent variable in
Cox regression. The independent variables were scores
on the revised cardiac risk index and findings on
coronary computed tomographic angiography.

Results

The primary outcome occurred in 74 patients (8%). The
model that included both scores on the revised cardiac
risk index and findings on coronary computed
tomographic angiography showed that coronary
computed tomographic angiography provided
independent prognostic information (P=0.014;
C index=0.66). The adjusted hazard ratios were 1.51 (95%
confidence interval 0.45 to 5.10) for non-obstructive
disease; 2.05 (0.62 to 6.74) for obstructive disease; and
3.76 (1.12 to 12.62) for extensive obstructive disease. For
the model with coronary computed tomographic
angiography compared with the model based on the
revised cardiac risk index alone, with 30 day risk
categories of 15% for the primary
outcome, the results of risk reclassification indicate that
in a sample of 1000 patients that coronary computed
tomographic angiography would have resulted
appropriately in 17 net patients receiving a higher risk
estimation among the 77 patients who would have
experienced the primary outcome (P<0.001). Coronary
computed tomographic angiography, however, would
have resulted inappropriately in 98 net patients
receiving a higher risk estimation, among the 923
patients who would not have experienced the primary
outcome (P<0.001). Among patients who had a
perioperative myocardial infarction, preoperative
coronary anatomy showed extensive obstructive disease
in 31% (22/71), obstructive disease in 41% (29/71),
non-obstructive disease in 24% (17/71), and normal
findings in 4% (3/71).

Conclusions

Though findings on coronary computed tomographic
angiography can improve estimation of risk for
patients who will experience perioperative
cardiovascular death or myocardial infarction, findings
are more than five times as likely to lead to an
inappropriate overestimation of risk among patients
who will not experience these outcomes. Perioperative
myocardial infarction occurs across the spectrum of
coronary artery disease, suggesting that there could be
several pathophysiologic mechanisms.

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