Preoperative risk assessment, medication management around surgery, and co-management of medical issues in surgical patients. Know when to bridge anticoagulation (hint: usually don't), when to order a stress test (hint: rarely), and which medications to hold or continue.
๐ Overview
Cardiac Risk Assessment
Revised Cardiac Risk Index (RCRI / Lee Index) -6 independent predictors of major cardiac events after non-cardiac surgery Lee, Circulation 1999:
High-risk surgery (intraperitoneal, intrathoracic, suprainguinal vascular)
History of ischemic heart disease
History of heart failure
History of cerebrovascular disease (stroke/TIA)
Diabetes on insulin
Creatinine > 2.0 mg/dL
RCRI Score
Risk of Major Cardiac Event
Approach
0
~3.9%
Low risk -proceed to surgery
1
~6.0%
Low-intermediate -proceed if good functional capacity (โฅ 4 METs)
2
~10.1%
Intermediate -consider stress testing if poor functional capacity AND will change management
โฅ 3
~15%
High risk -stress testing if will change management, cardiology consult
Functional Capacity
โฅ 4 METs = adequate functional capacity (low cardiac risk regardless of RCRI). 4 METs โ climbing one flight of stairs, walking on level ground at 4 mph, doing heavy housework (scrubbing floors, moving furniture). If a patient can do these activities without chest pain or dyspnea, they can likely tolerate surgery without further cardiac testing.
๐จ Management
Cardiac Medication Management
NEVER start a new beta-blocker within 24h of surgery. The POISE trial showed that starting metoprolol perioperatively increased stroke and death despite reducing MI. Only continue beta-blockers if the patient is already on one. POISE, NEJM 2008
Beta-blockers: CONTINUE if already on one (withdrawal can cause rebound tachycardia and ischemia). Do NOT start new ones perioperatively.
Statins: CONTINUE perioperatively -associated with reduced cardiac events and mortality.
ACE inhibitors/ARBs: Generally HOLD morning of surgery (risk of refractory hypotension with anesthesia). Resume postop when tolerating PO.
Anticoagulation Management
Agent
When to Stop
Bridge?
Key Notes
Warfarin
5 days before
Bridge with LMWH ONLY if HIGH thrombotic risk: mechanical mitral valve, recent VTE (< 3 months), CHAโDSโ-VASc โฅ 7
BRIDGE Trial, NEJM 2015 -most AF patients do NOT need bridging. Bridging increases bleeding without reducing thrombosis.
DOACs (apixaban, rivaroxaban)
2โ3 days before (longer if CrCl < 50 for dabigatran)
No bridging needed
Short half-lives. If urgent reversal needed: idarucizumab (dabigatran), andexanet alfa (Xa inhibitors), or PCC.
Aspirin
Continue for most surgeries
N/A
Exception: intracranial surgery -hold 7 days before. For most non-cardiac surgery, continuing aspirin is safe.
P2Y12 inhibitors (clopidogrel, ticagrelor)
Clopidogrel: 5 days. Ticagrelor: 3โ5 days.
No
If patient has recent coronary stent (< 6 weeks BMS, < 6 months DES), surgery should be delayed if possible. Cardiology consult.
๐ Updated Practice: Old teaching: stop anticoagulation and bridge all AF patients with heparin before surgery. Current practice: the BRIDGE trial (NEJM 2015) showed that most AF patients do NOT need bridging, no-bridging was non-inferior for thromboembolism and caused significantly less major bleeding. Bridge only for the highest-risk patients: mechanical mitral valve, recent VTE (<3 months), or very high CHA₂DS₂-VASc (≥7). When in doubt, don't bridge.
Diabetes Management
Metformin: HOLD day of surgery (risk of lactic acidosis with contrast or hypoperfusion). Resume when eating and renal function stable.
SGLT2 inhibitors: HOLD 3โ4 days before surgery (risk of euglycemic DKA -normal glucose but elevated ketones + anion gap). FDA Safety Communication, 2020
Basal insulin: Reduce to 50โ80% of usual dose the night before surgery. Do NOT hold completely (risk of DKA in type 1).
Bolus/prandial insulin: HOLD the morning of surgery (patient is NPO).
Oral agents (sulfonylureas, TZDs): HOLD morning of surgery.
GLP-1 agonists (semaglutide, liraglutide): May hold -risk of delayed gastric emptying and aspiration. ASA recommends holding day of surgery for daily formulations, 1 week for weekly formulations.
Pulmonary Risk Reduction
Updated Practice: Old teaching -get preop PFTs on everyone. WRONG -routine preop PFTs do NOT predict postoperative pulmonary complications and are NOT recommended. Clinical assessment (history, exam, functional capacity) is sufficient.
Incentive spirometry: Start preop and continue postop -reduces atelectasis and pneumonia.
Smoking cessation: Ideally โฅ 8 weeks before surgery if possible. Even 24โ48h of cessation reduces CO levels and improves Oโ delivery.
Avoid NG tube if possible (increases aspiration risk).
Early mobilization postop -most important intervention for preventing pulmonary complications.
๐งช Workup
Preoperative Testing
Only order tests that will change management. Routine "preop labs" without indication increase cost and false positives without improving outcomes.
ECG: If RCRI โฅ 1, known cardiac disease, or symptoms. Not needed for low-risk patients undergoing low-risk surgery.
CBC: If anticipated blood loss, anemia symptoms, or liver/renal disease.
BMP: If renal disease, diabetes, diuretic use, or major surgery with expected fluid shifts.
Coags (PT/INR): If on anticoagulants, liver disease, or bleeding history.
Type & screen: If blood loss anticipated.
Glucose: If diabetic -day-of-surgery glucose management.
Pregnancy test: All women of childbearing age (many institutions mandate this).
Stress test: Only if it will change management AND the patient has poor functional capacity (< 4 METs) AND elevated RCRI (โฅ 2). Do NOT get routine preop stress tests.
PFTs: NOT routinely indicated. Only if new/unexplained dyspnea or for lung resection surgery.
CXR: NOT routinely indicated. Only if acute pulmonary symptoms or significant cardiopulmonary disease.
Risk of refractory intraop hypotension. Resume when tolerating PO and hemodynamically stable.
Warfarin
STOP 5 days before
Bridge only for HIGH thrombotic risk (mechanical mitral valve, recent VTE <3mo).
DOACs
STOP 2โ3 days before
No bridging needed. Extend to 4โ5 days for dabigatran if CrCl < 50.
Aspirin
CONTINUE (most cases)
Hold for intracranial surgery. Otherwise, continue.
Metformin
HOLD day of surgery
Lactic acidosis risk with hypoperfusion/contrast.
SGLT2 inhibitors
HOLD 3โ4 days before
Euglycemic DKA risk perioperatively.
Basal insulin
Reduce to 50โ80% night before
Prevent hypoglycemia while NPO. Do NOT hold entirely in type 1.
Sulfonylureas
HOLD morning of surgery
Hypoglycemia risk while NPO.
GLP-1 agonists
HOLD (daily: day of; weekly: 1 wk)
Delayed gastric emptying โ aspiration risk with anesthesia.
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When do you bridge anticoagulation for a patient on warfarin undergoing elective surgery?
Bridge with LMWH ONLY for patients at HIGH thrombotic risk: (1) Mechanical mitral valve (or any mechanical valve with additional risk factors), (2) Recent VTE within 3 months, (3) Very high CHAโDSโ-VASc (โฅ 7). For the vast majority of AF patients, do NOT bridge. The landmark BRIDGE trial (NEJM 2015) showed that bridging in AF patients did not reduce thromboembolism but significantly increased major bleeding.
What is the RCRI (Revised Cardiac Risk Index)?
The RCRI (Lee Index) is the most widely used tool for preoperative cardiac risk stratification. It has 6 independent predictors (1 point each): (1) High-risk surgery (intraperitoneal, intrathoracic, suprainguinal vascular), (2) Ischemic heart disease, (3) Heart failure, (4) Cerebrovascular disease, (5) Diabetes on insulin, (6) Cr > 2.0. Score interpretation: 0 = ~3.9% risk of major cardiac event, 1 = ~6%, 2 = ~10%, โฅ3 = ~15%.
Why should you NOT start new beta-blockers perioperatively?
The POISE trial (NEJM 2008) randomized patients to extended-release metoprolol vs placebo started within 2โ4h before surgery. Results: metoprolol reduced MI (4.2% vs 5.7%) BUT doubled the rate of stroke (1.0% vs 0.5%) and increased overall mortality (3.1% vs 2.3%). The mechanism: beta-blockers cause perioperative hypotension and bradycardia โ cerebral hypoperfusion โ stroke.
When should you get a preoperative stress test?
Preop stress tests are indicated only when ALL THREE conditions are met: (1) The result will change management (i.e., you would cancel or modify the surgery based on the result). (2) The patient has poor functional capacity (< 4 METs -cannot climb one flight of stairs). (3) The patient has elevated cardiac risk (RCRI โฅ 2 or known significant cardiac disease). If any of these is missing, a stress test is NOT indicated.
Postoperative Monitoring
Parameter
Frequency
Target / Action
Vitals
q4h floor, q1โ2h PACU
Watch for hypotension (bleeding, sepsis), tachycardia (pain, PE, bleeding), fever.
10 breaths q1h. Prevents atelectasis and postop pneumonia.
โก Summary
Perioperative Medicine -Key Points
Cardiac Risk
RCRI: 6 predictors. โฅ4 METs = low risk regardless. Stress test only if poor functional capacity + elevated RCRI + will change management.
Beta-blockers
CONTINUE if on them. NEVER start new within 24h of surgery (POISE -โ stroke + death). Withdrawal is also dangerous.
Anticoagulation
Warfarin: stop 5 days. Bridge ONLY for mechanical mitral valve, VTE <3mo, very high CHAโDSโ-VASc. BRIDGE trial: most AF patients do NOT need bridging.
Diabetes
Hold metformin day of surgery. Hold SGLT2i 3โ4 days before (euglycemic DKA). Reduce basal insulin to 50โ80%. Hold orals AM of surgery.
Pulmonary
Routine preop PFTs NOT recommended. Incentive spirometry, smoking cessation โฅ8wk, early postop mobilization. No routine CXR.
SGLT2i Pearl
Hold empagliflozin/dapagliflozin 3โ4 days preop. Risk of euglycemic DKA -normal glucose but elevated ketones + anion gap acidosis.