Pre-Surgical Risk Stratification

Perioperative Risk: A Multidisciplinary Framework

1. ACC/AHA Stepwise Algorithm (Cardiology)

Step 1: Is surgery emergent? If yes, proceed to OT. No further testing changes management.

Step 2: Active Cardiac Condition (ACS, decompensated HF, significant arrhythmia, severe valvular disease)? If yes, delay surgery and obtain cardiology consultation.

Step 3: Low-risk surgery (<1% MACE)? If yes, proceed without further cardiac testing.

Step 4: Adequate functional capacity (≥4 METs) without symptoms? If yes, proceed without further testing.

Step 5: Poor/unknown functional capacity: use RCRI. RCRI 0-1 = proceed. RCRI ≥2 = consider pharmacological stress testing ONLY if it will change management.

2. The 4-MET Question (Physician's Bedside Tool)

Pathophysiology: 1 MET = 3.5 mL O2/kg/min. Surgery imposes 4-6 METs of stress. If a patient cannot achieve 4 METs, their cardiopulmonary reserve cannot tolerate surgical stress. This single bedside question has superior predictive value to most laboratory tests.

Bedside Pearl: "Can you climb one flight of stairs without stopping?" or "Can you walk 500 metres on flat ground without breathlessness?" If yes, functional capacity is likely ≥4 METs.

3. RCRI (Lee Index, 1999)

Score: 0 = 3.9% MACE; 1 = 6.0%; 2 = 10.1%; 3+ = 15%+. The critical threshold is 2: RCRI ≥2 with poor functional capacity triggers the decision for non-invasive stress testing.

Indian Context: South Asian patients may carry higher baseline cardiovascular risk due to the "thin-fat" Indian phenotype (visceral adiposity with normal BMI), higher insulin resistance, and earlier-onset CAD. Yaddanapudi et al. recommend a lower threshold for cardiac evaluation in Indian patients with metabolic syndrome even when RCRI appears reassuring.

4. STOP-BANG and Non-Obese OSA

Score: 0-2 = Low; 3-4 = Intermediate; 5-8 = High risk for OSA. Score ≥3 mandates postoperative continuous pulse oximetry and caution with opioid analgesia.

Non-Obese OSA Pearl: STOP-BANG was validated in predominantly obese Western populations. In non-obese or underweight elderly patients (common in India), a score of 3-4 driven solely by age + gender + hypertension has lower specificity for obstructive sleep apnoea. Consider central sleep apnoea or upper-airway anatomical factors rather than classic obesity-driven OSA. Clinical correlation is essential.

5. Caprini VTE and Indian Context

Pathophysiology (Virchow's Triad): Surgery activates all three arms: endothelial injury, stasis, and hypercoagulability. VTE is the most preventable cause of in-hospital death.

Indian Data: The ASI guidelines recommend pharmacological thromboprophylaxis for Caprini ≥3. While historically VTE was considered less common in Indians, recent data from Agarwala et al. show comparable VTE incidence when systematically screened, and under-prophylaxis remains a concern.

6. Medication Reconciliation: The Details That Save Lives

CONTINUE: Beta-blockers, statins, thyroid replacement, antiepileptics, inhaled bronchodilators.

HOLD: ACEi/ARBs (morning of surgery), metformin (24-48 hrs), SGLT2 inhibitors (3 days, euglycaemic DKA risk), oral hypoglycaemics (morning of surgery).

DAPT and Stents: BMS: defer elective surgery ≥30 days. DES: defer 6-12 months. Premature DAPT discontinuation causes stent thrombosis with >30% mortality.

Neuraxial + Anticoagulation: Epidural haematoma risk. Warfarin must have INR <1.5. LMWH: last dose ≥12 hrs (prophylactic) or ≥24 hrs (therapeutic) before neuraxial block.

Stress-Dose Steroids: Patients on ≥5 mg prednisone daily for ≥3 weeks need hydrocortisone 50-100 mg IV at induction.

7. Prehabilitation Checklist

Smoking: Cessation ≥4 weeks preop reduces pulmonary complications by 30-40%.

Glycaemic Control: HbA1c >8% = 2-3x higher SSI. Target perioperative glucose 140-180 mg/dL (NICE-SUGAR).

Anaemia: Hb <10 g/dL independently increases 30-day mortality. IV iron infusion 2-4 weeks preop can restore Hb. Particularly relevant in India where nutritional anaemia is highly prevalent.