What is the risk stratification for a patient with severe aortic stenosis undergoing hip replacement?

Risk Stratification for Severe Aortic Stenosis in Hip Replacement Surgery

Patients with severe aortic stenosis undergoing hip replacement face substantial perioperative mortality risk (approximately 10%), and the critical decision hinges on whether the aortic stenosis is symptomatic or asymptomatic, the surgical urgency, and the patient's baseline surgical risk profile. 1

Primary Risk Stratification Framework

Symptomatic vs. Asymptomatic Status

If the severe aortic stenosis is symptomatic, elective hip replacement should be postponed or canceled, and the patient requires aortic valve replacement (AVR) before proceeding with orthopedic surgery. 1 This represents the highest-risk scenario where proceeding without valve intervention is rarely appropriate. 1

If the severe aortic stenosis is asymptomatic but has not been evaluated within the past year, the hip surgery should be postponed for updated cardiac assessment. 1

Severity Grading Beyond "Severe"

The guidelines distinguish between standard severe AS and very severe AS, which impacts risk stratification: 1

• Very severe AS (peak velocity ≥5 m/sec or mean gradient ≥60 mmHg) identifies patients at increased risk for death and carries higher perioperative risk 1
• Standard severe AS (peak velocity 4.0-4.9 m/sec or mean gradient ≥40 mmHg) still represents significant risk but may be stratified differently based on other factors 1

Left Ventricular Function Assessment

Reduced ejection fraction (<50%) in the setting of severe AS dramatically increases perioperative risk and makes AVR appropriate regardless of surgical risk category before elective noncardiac surgery. 1 Even mildly reduced LVEF may indicate reduced ventricular reserve and overestimate true LV performance in the context of valvular disease. 1

Surgical Urgency Considerations

Urgent Hip Fracture Scenarios

For patients presenting with acute hip fracture and severe AS, a multidisciplinary approach is essential, as delayed hip surgery increases disability and mortality, but untreated AS increases perioperative risk. 2 Management options include:

• Hip correction under hemodynamic monitoring followed by valve replacement 2
• Preoperative balloon aortic valvuloplasty (BAV) to allow hip fracture surgery followed by definitive valve replacement 2
• Preoperative minimalist transcatheter aortic valve replacement (TAVR) for selected patients 2

Balloon aortic valvuloplasty may be reasonable as a bridge to surgery in hemodynamically unstable patients with AS who are at high risk for AVR and cannot undergo valve replacement due to serious comorbidities. 1

Elective Hip Replacement

For elective hip replacement in patients refusing cardiac surgery or who are not candidates for AVR, noncardiac surgery can be performed but carries approximately 10% mortality risk. 1 This represents a high-risk but potentially acceptable scenario when valve intervention is not feasible.

Additional Risk Modifiers

Baseline Surgical Risk Profile

The patient's baseline surgical risk (low, intermediate, or high) modifies the appropriateness of proceeding: 1

• Low surgical risk patients with asymptomatic severe AS may have AVR considered appropriate before elective surgery, particularly with predictors of rapid progression 1
• High or intermediate surgical risk patients face compounded risk when severe AS is present 1

Predictors of Rapid Progression

Even in asymptomatic patients, the presence of predictors of symptom onset or rapid progression increases risk and may warrant pre-operative AVR: 1

• Rate of velocity progression >0.3 m/s per year 1
• Severe valve calcification 1
• Elevated BNP 1
• Excessive LV hypertrophy in the absence of hypertension 1

Common Pitfalls to Avoid

Do not rely solely on aortic valve area cutoff values, as these parameters can be inconsistent and may overemphasize risk in some patients. 3 The perioperative risk depends on severity (moderate vs. severe), clinical status, and surgical complexity. 3

Do not assume all "asymptomatic" severe AS has benign prognosis—symptoms are subjective and depend on lifestyle, and observational data show natural history is not benign. 4 Survival at 1,2, and 5 years in unoperated asymptomatic severe AS patients was only 67%, 56%, and 38% respectively. 4

Recognize that older studies may overemphasize AS significance due to outdated echocardiographic techniques, anesthetic methods, and postoperative care standards. 3

Risk Stratification Algorithm

1. Determine symptom status: Symptomatic severe AS → postpone elective hip surgery, pursue AVR first 1

2. If asymptomatic, assess severity markers: Very severe AS (Vmax ≥5 m/sec) → higher risk, strongly consider pre-operative intervention 1

3. Evaluate LV function: LVEF <50% → AVR appropriate before elective surgery regardless of surgical risk 1

4. Assess surgical urgency: Acute hip fracture → consider BAV as bridge or expedited TAVR before hip repair 2

5. Identify progression predictors: Rapid velocity progression, severe calcification, elevated BNP, excessive LVH → favor pre-operative AVR even if asymptomatic 1

6. Consider patient candidacy for valve intervention: If not a candidate for AVR → hip surgery can proceed with ~10% mortality risk and intensive hemodynamic monitoring 1