18.1 Preoperative Cardiovascular Risk Assessment

Perioperative medical consultation is a core competency in internal medicine. The primary goal is not to "clear" a patient for surgery, but rather to perform an evidence-based risk stratification, identify modifiable clinical risk factors, optimize chronic medical conditions, formulate perioperative medication plans, and anticipate and manage postoperative complications.

1. Preoperative Cardiovascular Risk Assessment

Cardiovascular complications—including myocardial infarction (MI), acute heart failure, malignant arrhythmias, and cardiac arrest—are the leading causes of perioperative morbidity and mortality in noncardiac surgery.

Revised Cardiac Risk Index (RCRI / Lee Index)

The Revised Cardiac Risk Index (RCRI) is the most widely validated clinical tool for estimating perioperative Major Adverse Cardiac Events (MACE: defined as myocardial infarction, pulmonary edema, ventricular fibrillation, primary cardiac arrest, or complete heart block).

Risk Stratification by RCRI Score

• Class I (0 Points): 3.9% baseline risk of major adverse cardiac events (Low Risk)
• Class II (1 Point): 6.0% risk of major adverse cardiac events (Low-to-Moderate Risk)
• Class III (2 Points): 10.1% risk of major adverse cardiac events (Moderate Risk)
• Class IV (>= 3 Points): 15.0% risk of major adverse cardiac events (High Risk)

ACC/AHA Stepped Perioperative Cardiovascular Algorithm

The American College of Cardiology / American Heart Association (ACC/AHA) guidelines outline a systematic 5-step clinical decision algorithm for evaluating cardiac risk prior to elective noncardiac surgery:

1. Step 1 — Emergency Surgery: Determine surgical urgency. If the surgery is an emergency (life- or limb-threatening procedure where delay significantly increases morbidity/mortality, e.g., ruptured aortic aneurysm, perforated viscus, acute compartment syndrome), proceed directly to the operating room without cardiac testing. Perform clinical risk assessment and cardiac surveillance postoperatively.
2. Step 2 — Active Cardiac Conditions: Screen for unstable, active cardiac conditions that mandate immediate cardiology evaluation and optimization before elective surgery:
   • Acute Coronary Syndromes (ACS): Unstable angina, recent acute myocardial infarction (< 30–60 days).
   • Decompensated Heart Failure: NYHA Class IV symptoms, worsening dyspnea at rest, new/worsened pulmonary edema.
   • Significant Arrhythmias: High-grade AV block (Mobitz II second-degree or third-degree heart block), symptomatic ventricular arrhythmias, newly recognized supraventricular tachycardias or atrial fibrillation with rapid ventricular response (RVR).
   • Severe Symptomatic Valvular Heart Disease: Severe symptomatic aortic stenosis (mean aortic valve gradient >= 40 mmHg, peak velocity >= 4.0 m/s, or aortic valve area < 1.0 cm2) or severe symptomatic mitral stenosis. (Symptomatic severe AS requires surgical or transcatheter aortic valve replacement [TAVR/SAVR] prior to elective noncardiac surgery).
3. Step 3 — Low-Risk Surgical Procedures: If the procedure has a low estimated MACE risk (< 1%; e.g., cataract extraction, minor dermatologic/superficial excisions, breast biopsy, diagnostic endoscopy), proceed directly to surgery without any preoperative cardiac testing, regardless of patient comorbidities.
4. Step 4 — Functional Capacity Assessment in Elevated-Risk Surgery: For procedures with elevated risk (>= 1% MACE; e.g., major orthopedic arthroplasty, intra-abdominal, intrathoracic, or vascular surgery), assess functional capacity measured in Metabolic Equivalents of Task (METs):
   • Good to Excellent Functional Capacity (>= 4 METs): Able to climb a flight of stairs or walk up a hill without stopping, walk on level ground at 4 mph (6.4 km/h), carry heavy groceries, or perform heavy housework. Patients with >= 4 METs can proceed directly to surgery without further cardiac testing, even if they have an elevated RCRI score.
   • Poor or Unknown Functional Capacity (< 4 METs): Unable to walk 2 blocks on level ground or climb 1 flight of stairs without stopping due to dyspnea, angina, or severe physical deconditioning/osteoarthritis.
5. Step 5 — Selective Cardiac Testing: In patients with poor or unknown functional capacity (< 4 METs) undergoing elevated-risk surgery:
   • If the patient has an elevated RCRI score (>= 1) and non-invasive stress testing will change clinical management (e.g., prompt coronary revascularization for high-risk CAD or influence surgical decision-making), obtain a non-invasive Pharmacologic Stress Test (Dobutamine Stress Echocardiography or Vasodilator Myocardial Perfusion Imaging [MPI] with Regadenoson/Adenosine SPECT).
   • If stress testing will not change clinical management (e.g., patient is not a revascularization candidate or the surgical plan will proceed regardless), proceed to the OR with medical optimization.
   • Crucial Board Rule: Routine preoperative coronary angiography or prophylactic coronary revascularization (CABG/PCI) in stable patients prior to noncardiac surgery is NOT recommended (CARP and DECREASE-V trials demonstrated no reduction in perioperative mortality or MI compared to medical optimization).

Preoperative Beta-Blocker Management

• Chronic Beta-Blocker Therapy: Patients receiving chronic beta-blocker therapy (for CAD, heart failure, arrhythmias, or hypertension) MUST continue their beta-blocker throughout the entire perioperative period. Abrupt cessation on the day of surgery causes acute sympathetic rebound, tachycardia, severe hypertension, myocardial ischemia, and significantly increased perioperative mortality.
• Beta-Blocker-Naive Patients: NEVER start high-dose beta-blockers acutely on the morning of surgery. Landmark trial evidence (POISE Trial) showed that initiating high-dose oral metoprolol succinate on the day of surgery reduced nonfatal myocardial infarction but resulted in a statistically significant increase in total mortality, severe intraoperative hypotension, and fatal/disabling ischemic strokes.
• Guideline Recommendation: If a beta-blocker is clinically indicated in a high-risk, beta-blocker-naive patient (e.g., known CAD undergoing high-risk vascular surgery), it must be initiated days to weeks (ideally > 7 to 30 days) prior to elective surgery and slowly titrated to a target resting heart rate of 60–80 bpm while ensuring systolic blood pressure remains >= 100 mmHg.