Perioperative Management & Risk Assessment
A Step 2 CK management lesson on perioperative risk assessment for non-cardiac surgery: the ACC/AHA stepwise algorithm, RCRI scoring, the ≥4-MET functional-capacity rule that stops most workups, and evidence-based perioperative medication management (beta-blockers, DAPT/stent timing, anticoagulation bridging, SGLT2/metformin, steroids). Emphasis throughout is the \"next best step\" — optimize and proceed, and test only when it changes management.
Framing the perioperative question
Perioperative evaluation before non-cardiac surgery is not a pass/fail "clearance" — it is a structured decision to optimize and proceed, delay, or (rarely) cancel. The vast majority of patients proceed to surgery; the exam reward is knowing when not to order more testing.
Four inputs drive every decision:
- Urgency — emergency surgery goes to the OR regardless of risk (no time for testing).
- Active/unstable cardiac conditions — acute coronary syndrome, decompensated heart failure, unstable arrhythmia, or symptomatic severe valvular disease (esp. severe aortic stenosis) must be evaluated and treated before elective surgery.
- Patient risk — quantified with the Revised Cardiac Risk Index (RCRI) or an NSQIP calculator.
- Functional capacity — one of the most useful bedside data points.
The core principle (ACC/AHA): order a preoperative stress test only if the result would change management. In a stable patient who can climb two flights of stairs, it will not.
- Emergency surgery → straight to OR. Provide perioperative surveillance and medical optimization; do NOT delay for cardiac stress testing.
- Screen for unstable cardiac conditions first (ACS, decompensated HF, high-grade/unstable arrhythmia, symptomatic severe AS). Any of these → evaluate/treat before elective surgery.
- Functional capacity ≥4 METs (climb 2 flights of stairs, walk up a hill, walk ~4 mph) → proceed without further cardiac testing, even if the risk score is "elevated."
- Stress test only if it changes management — i.e., elevated risk AND poor/unknown functional capacity AND a positive result would lead to revascularization or a changed plan.
- Do NOT start a beta-blocker on the day of surgery (POISE trial: fewer MIs but MORE strokes and deaths). Continue chronic beta-blockers and continue statins perioperatively.
- No routine preoperative ECG, CXR, or coagulation panel in asymptomatic patients having low-risk surgery.
- Don't stop aspirin in a patient with a recent coronary stent; don't bridge every warfarin patient.
ACC/AHA stepwise algorithm (next best step)
| Step | Question | If YES → | If NO → |
|---|---|---|---|
| 1 | Is surgery an emergency? | Proceed to OR; optimize + surveillance | Go to step 2 |
| 2 | Active/unstable cardiac condition (ACS, decompensated HF, unstable arrhythmia, severe symptomatic valve dz)? | Evaluate & treat before elective surgery | Go to step 3 |
| 3 | Estimate perioperative MACE risk (RCRI/NSQIP). Is it low (<1%)? | Proceed to surgery | Go to step 4 |
| 4 | Elevated risk: is functional capacity ≥4 METs? | Proceed to surgery (no further cardiac testing) | Go to step 5 |
| 5 | Poor/unknown capacity: would stress testing change management? | Pharmacologic stress test (dobutamine echo / vasodilator MPI) | Proceed with medical optimization |
Revised Cardiac Risk Index (RCRI / Lee)
| # | RCRI predictor | |
|---|---|---|
| 1 | High-risk surgery (intraperitoneal, intrathoracic, or suprainguinal vascular) | |
| 2 | History of ischemic heart disease | |
| 3 | History of congestive heart failure | |
| 4 | History of cerebrovascular disease (stroke/TIA) | |
| 5 | Insulin-treated diabetes mellitus | |
| 6 | Preoperative creatinine >2.0 mg/dL | |
| Points | Risk category | Approx. MACE |
| 0 | Low | ~0.4% |
| 1 | Low | ~0.9% |
| 2 | Elevated | ~6.6% |
| ≥3 | Elevated | ~11% |
A 68-year-old man with insulin-treated type 2 diabetes, hypertension, and a prior MI with drug-eluting stent placed 2 years ago is scheduled for elective total hip arthroplasty. He has no chest pain or dyspnea and climbs two flights of stairs to his apartment daily without stopping. Meds: metoprolol, atorvastatin, lisinopril, aspirin, insulin glargine.
Next best step in management?
➡️ Proceed to surgery — no further cardiac (stress) testing.
- His RCRI = 2 (ischemic heart disease + insulin-treated DM; hip arthroplasty is not an RCRI "high-risk" surgery) → elevated risk, BUT functional capacity ≥4 METs overrides the score and stops the workup.
- Continue metoprolol and atorvastatin perioperatively (never start/stop a beta-blocker on the day of surgery).
- Continue aspirin (secondary prevention after prior DES).
- Hold the morning lisinopril per protocol (intraoperative hypotension) and reduce basal insulin (give ~50–75% of the usual long-acting dose, hold prandial while NPO), targeting glucose 140–180 mg/dL.
- A pre-op stress test here would be a classic wrong answer — it would not change management.
Perioperative medication management
| Drug | Perioperative action |
|---|---|
| Beta-blocker | Continue. Do NOT start high-dose the day of surgery (POISE). |
| Statin | Continue. Reasonable to start before vascular surgery. |
| Aspirin | Continue with recent coronary stent/high CV risk; otherwise usually hold ~5–7 days (POISE-2: ↑bleeding, no net cardiac benefit for primary prevention). |
| P2Y12 inhibitor (clopidogrel, etc.) | Hold ~5–7 days before elective surgery — UNLESS within the stent DAPT window, in which case delay the surgery instead. |
| ACE-I / ARB | Commonly held the morning of surgery (hypotension); continuation is also reasonable. |
| Warfarin | Stop 5 days prior. Bridge with LMWH only if high thrombotic risk (mechanical mitral valve, recent VTE/stroke <3 mo). |
| DOAC | Stop 1–2 days prior (longer with high bleeding risk or reduced CrCl, esp. dabigatran). No bridging. |
| Metformin | Hold the day of surgery (renal/contrast-related lactic acidosis risk). |
| SGLT2 inhibitor | Hold 3–4 days before surgery (euglycemic DKA risk). |
| Chronic glucocorticoids | Stress-dose for major surgery if adrenally suppressed (>20 mg prednisone/day for >3 weeks). |
A 62-year-old woman had a drug-eluting stent (DES) placed 8 weeks ago for stable angina and is on aspirin + clopidogrel (DAPT). She now requests elective laparoscopic cholecystectomy for recurrent biliary colic.
Next best step in management?
➡️ Postpone the elective surgery until she has completed the recommended DAPT course (ideally ≥6 months after DES), continuing aspirin throughout.
- Stopping DAPT early is the leading cause of stent thrombosis, which is frequently fatal.
- Minimum elective-surgery delays after coronary intervention:
- Balloon angioplasty (no stent): ≥14 days
- Bare-metal stent: ≥30 days
- Drug-eluting stent: ideally ≥6 months (3–6 months acceptable only if the surgery cannot wait and ischemic risk is acceptable, via cardiology/surgery discussion).
- If surgery were truly time-sensitive: proceed with a multidisciplinary plan, continue aspirin (and P2Y12 where feasible), minimizing the interruption.
Minimum NPO times before elective anesthesia (ASA guidelines):
- 2 hours — clear liquids (water, black coffee, pulp-free juice)
- 4 hours — breast milk
- 6 hours — infant formula, non-human milk, and a light meal
- 8 hours — fried/fatty foods or a heavy (meat) meal
The goal is to minimize gastric volume and aspiration risk on induction.
- Ordering a stress test when functional capacity is ≥4 METs, or when the result wouldn't change management — the classic distractor.
- Starting a beta-blocker on the day of surgery — increases stroke/mortality (POISE).
- Bridging every warfarin patient — bridge only high thrombotic-risk patients (mechanical mitral valve, recent VTE/stroke); routine bridging in AFib increases bleeding without benefit (BRIDGE trial).
- Forgetting to hold an SGLT2 inhibitor → post-op euglycemic DKA.
- Stopping aspirin/DAPT and operating within the stent window → stent thrombosis.
- "Clearing" a patient with unrecognized symptomatic severe aortic stenosis or decompensated HF — these active conditions must be addressed first.
- Continuing metformin through surgery — hold it the day of the procedure.
Practice Clinical Management now
Board-style questions, spaced-repetition flashcards, and a Socratic AI tutor — free to start.