Cardiac Risk Assessment

Question 1

CABG operative mortality rate

Answer 1

5-6%

Higher mortality since higher patient acuity (lower-risk patients treated with PCI now)

Question 2

Risk of adverse cardiac events after CABG with perioperative MI

Answer 2

If perioperative MI occurs, 50% risk of ongoing ACE at 2 years

Question 3

Postoperative MI incidence

Answer 3

2-10%

Question 4

What is myocardial reperfusion injury?

Answer 4

Myocardial injury extending beyond the initial ischemic insult due to the metabolic cascade accompanying ischemia and reperfusion.

Adequate myocardial protection during cross clamp is important to prevent reperfusion injury after cross clamp released.

Question 5

What is no-reflow phenomenon?

Answer 5

Failure of reperfusion despite resolution of proximal coronary obstruction.

May be due to damaged distal microvasculature resulting in impaired flow despite reliving proximal occlusion.

Question 6

What is myocardial stunning?

Answer 6

Transient myocardial dysfunction occurring after ischemia-reperfusion. Not accompanied by myocardial necrosis.

Common cause of new RWMA and decreased LVEF after surgery; may be due to ROS damage or altered calcium flux.

Question 7

How long does it take for irreversible myocardial injury develop during ischemia?

Answer 7

20 minutes

Myocardial injury can be reversed if perfusion is reestablished within 16-20 mins

Question 8

What is the wavefront phenomenon?

Answer 8

Tissue necrosis originating in the subendocardial region and extending to the subepicardial region

Question 9

What is the universal definition of myocardial infarction?

Answer 9

Clinical evidence of acute ischemia (on EKG or imaging) and the rise and/or fall of cardiac biomarkers with at lest one value above the 99th percentile of the upper reference limit.

Question 10

To diagnose MI immediately after cardiac surgery, cardiac biomarkers must be more than ___ times the 99th percentile of the upper reference limit

Answer 10

10 times the 99th percentile of the upper reference limit

Question 11

What is the most sensitive serum biomarker for myocardial infarction?

Answer 11

Troponin I

(Skeletal muscle expresses proteins that may be detected by the Troponin T assay and lead to a false positive)

Question 12

What serum cardiac biomarker is associated with late adverse outcomes after cABG?

Answer 12

CK-MB

Question 13

What serum cardiac biomarker is elevated early in myocardial injury and decreases quickly after the insult?

Answer 13

BNP

Is useful for detecting new injury after a recent MI

Question 14

Which preoperative risk factors are associated with the greatest operative mortality rates based on the STS database?

Answer 14

• Salvage status
• Renal failure
• Emergency surgery
• Multiple reoperations
• NYHA Class IV status (CHF symptoms at rest)

Question 15

What are the three STS risk models?

Answer 15

• CABG model: isolated CABG
• Valve model: isolated AVR, MVR, or MVr
• CABG + valve model: CABG + AVR, MVR, or MVr

Question 16

Risk factors for readmission after CABG (patient and provider)

Answer 16

Patient:
- Postoperative infection
- Heart failure
- Older age
- Female
- African-American
- Higher BSA
- Acute MI within 1 week

Provider:
- <100 CABG cases/year (low annual case volume)
- High hospital risk-adjusted mortality rate
- Discharge to SNF or nursing home
- Hospital LOS >5 days

Question 17

Risk factors for perioperative AKI

Answer 17

• Older age
• Gender
• Prior CABG
• DM
• Preop IABP
• Preop anemia
• Intraop pRBC
• Postop mediastinal exploration

Question 18

Proinflammatory protein that may contribute to thrombotic and inflammatory complications

Answer 18

CD40 ligand

• Associated with thrombosis and inflammatory responsis
• Derived from platelets
• Levels increase during bypass and return to baseline ~8 hours after CPB

Question 19

How long does it take for RWMA to be detected on TEE after ischemia?

Answer 19

Within 10-15 seconds after onset of ischemia