Cardiac Evaluation

Cardiovascular Assessment

• Goals of cardiovascular assessment:
  • Identify risk of heart disease based on risk factors
  • Identify presence and severity of heart disease
  • Determine need for further preoperative testing
  • Modify the risk of perioperative cardiac events

Cardiac Risk Index

• Six independent predictors of complications:
  • High-risk type of surgery
  • History of ischemic heart disease
  • History of congestive heart failure
  • History of cerebrovascular disease
  • Preoperative treatment with insulin
  • Preoperative serum creatinine >2.0 mg/dL

Hypertension

• Defined: 2 or more BP readings of >140/90 mmHg
• Increases in frequency with age
• Duration and severity correlate with end-organ involvement
• Ischemic heart disease is the most common form of end-organ damage with hypertension
• SBP 20mmHg, DBP 10 mmHg change → doubles lifetime risk of CV disease
• HTN in young people? Dig deeper, there is likely another cause

Clinical Predictors of CV Risk

• 30% of patients in the OR have heart disease (and it’s not diagnosed)
• Two biggest risk factors: Male and Increasing Age
• Other risk factors:
  • Hypercholesterolemia
  • Systemic hypertension
  • Cigarette smoking
  • Diabetes mellitus
  • Obesity
  • Sedentary lifestyle
  • Family history of premature development of ischemic heart disease

Symptoms of Heart Disease

• Symptoms usually only develop after demand exceeds supply
• Chronic stable angina:
  • Chest pain that does not change appreciably in frequency or severity over 2 months or longer
• Unstable angina:
  • Angina at rest
  • Angina of new onset
  • Increase in the severity or frequency of previously stable angina without an increase in levels of cardiac biomarkers

METS (Metabolic Equivalent)

• Exercise tolerance is one of the most important determinants of perioperative risk
• Excellent exercise tolerance, even in patients with stable angina, suggests the myocardium can be stressed
• Dyspnea with chest pain during minimal exertion raises the probability of extensive CAD
• Increased risk of developing hypotension with ischemia
• Likelihood of serious adverse events inversely related to number of blocks a patient can walk

Duke Activity Status Index (DASI)

• Helps to identify patients at risk for:
  • Myocardial injury
  • Myocardial infarction
  • Moderate-to-severe complications
  • New disability
• Some data suggest DASI is moderately correlated with LV function
• Surrogate for echo when LV function is the goal

Cardiac Testing

• 12 lead EKG:
  • 30% of MIs occur without symptoms
  • No longer “age based”
  • Males over 65
  • Anyone with a positive history
  • Those that you suspect to be at risk
• Exercise EKG:
  • Tries to induce ischemia if present
  • “Positive” if >1 mm of horizontal or down-sloping ST-segment depression during or within 4 minutes after exercise
• Nuclear stress testing:
  • Looks at coronary perfusion; greater sensitivity than exercise stress
  • Useful in those that cannot exercise
• Stress Echo
• Stress MRI
• Calcium CT
• Cardiac Cath:
  • Best information about condition of the coronaries

Cardiac Evaluation Algorithm

• Coronary Plaque:

  • There is NO DIAGNOSTIC test that can predict stability of coronary plaque
  • Best you will get is information about amount of plaque
  • You have no idea when it will rupture

• Almost two thirds of patients describe new-onset angina pectoris or a change in their angina pattern during the 30 days preceding an acute MI.### Coronary Disease Treatment

• Identification and treatment of diseases that can precipitate or worsen ischemia are crucial

• Reduction of risk factors for coronary artery disease is essential

• Lifestyle modification and pharmacologic management of angina are vital

• Revascularization by coronary artery bypass grafting (CABG) or percutaneous coronary intervention (PCI) with or without placement of intracoronary stents is a treatment option

PCI and Stents

• There are two main types of stents: bare metal and drug-eluting
• Both types of stents are at risk of thrombus formation and require antiplatelet therapy
• Clopidogrel discontinuation is the most significant independent predictor of stent thrombosis (14 times)
• The longer the wait to stop antiplatelet therapy, the better
• Heparin "bridging" is not recommended and can be detrimental

Stent-Specific Guidelines

• Bare metal stents: must wait at least 30 days for elective surgery, consider dual antiplatelet therapy
• Drug-eluting stents: must wait at least 6 months for elective surgery

Perioperative MI and Heart Failure

• Heart failure is a contraindication for elective surgery in acute cases
• Preoperative predictors of MI include heart failure, systolic dysfunction, and decreased EF
• Ischemia is a major cause of heart failure, while diastolic dysfunction is caused by increased filling pressures and abnormal relaxation
• Hypertension is a major cause of diastolic dysfunction

Heart Failure Evaluation

• Brain natriuretic peptide (BNP) is released in response to ischemia or strain and is a useful marker for decompensated heart failure
• BNP is a powerful marker of CV disease in nonsurgical patients and helps predict risk in non-cardiac surgery
• EKG, BUN, Creatinine, and BNP are indicated in heart failure, with guidelines suggesting echo to assess
• Surgery should be postponed in decompensated or untreated heart failure

Focused Preoperative Cardiac Assessment

• Focused questions should include history of MI
• A thorough assessment is necessary to identify and minimize the effects of heart failure