What is the management approach for a patient with aortic stenosis (AS) and a history of ankylosing spondylitis?

Management of Low-Flow, Low-Gradient Aortic Stenosis

In patients with low-flow, low-gradient (LFLG) aortic stenosis, aortic valve replacement should be performed if true severe stenosis is confirmed by dobutamine stress echocardiography showing contractile reserve or by aortic valve calcium scoring, as these patients have the worst prognosis among AS subtypes but benefit greatly from intervention. 1, 2, 3

Diagnostic Confirmation Strategy

The critical first step is distinguishing true severe AS from pseudo-severe AS, as management hinges entirely on this determination 2, 3:

• Dobutamine stress echocardiography (DSE) is the primary diagnostic tool to assess contractile reserve and confirm stenosis severity 4, 1, 2

  • If aortic valve area remains ≤1.0 cm² and mean gradient increases to >40 mmHg with dobutamine, this confirms true severe AS 2, 3
  • Presence of contractile reserve (increase in stroke volume >20%) indicates patients who will benefit from valve replacement 1, 2

• Aortic valve calcium scoring by multidetector CT serves as an alternative or complementary method 1, 2, 3

  • Severe calcification (>2000 Agatston units in men, >1250 in women) confirms true severe AS even with low gradients 2, 3
  • This is particularly useful when DSE is inconclusive or contraindicated 3

• Projected effective orifice area at normal flow rates can distinguish severe from pseudo-severe AS in both reduced and preserved LVEF 2

Treatment Algorithm Based on Findings

True Severe AS with Contractile Reserve Present

Proceed with aortic valve replacement 4, 1, 2:

• These patients have the worst prognosis without intervention but benefit greatly from valve replacement 2, 3
• Transcatheter AVR (TAVR) via transfemoral approach may be superior to surgical AVR in LFLG AS patients 3
• The choice between TAVR and surgical AVR depends on surgical risk assessment (STS-PROM score), age, frailty, and anatomical considerations 1

True Severe AS WITHOUT Contractile Reserve

Surgery may be considered but carries higher risk 4:

• European guidelines give this a Class IIb recommendation (may be considered) 4
• Careful assessment of surgical futility is essential—consider life expectancy, comorbidities, and likelihood of functional improvement 1
• Multidisciplinary Heart Valve Team discussion is mandatory to weigh risks versus potential benefits 1

Pseudo-Severe AS (Normal Valve Area with Dobutamine)

Do NOT proceed with valve replacement 2:

• These patients have outcomes comparable to moderate AS and do not benefit from AVR 2
• Focus on medical management of heart failure and LV dysfunction 4
• Serial echocardiographic surveillance every 6-12 months 1

Special Considerations for Ankylosing Spondylitis Patients

When LFLG AS occurs in the context of ankylosing spondylitis, additional factors require attention 5, 6, 7:

• Aortitis and aortic root involvement are common in AS patients, occurring in 2-10% and increasing with disease duration 5, 6, 7
• Surgical AVR may be preferred over TAVR due to frequent need for aortic root replacement in AS-related aortitis 5, 6
• Ensure optimal rheumatologic disease control before and after cardiac surgery, as cardiopulmonary bypass may exacerbate AS activity 6
• Screen for conduction abnormalities preoperatively, as subaortic fibrotic extension into the interventricular septum is common 5, 7
• Evaluate coronary arteries carefully, as AS patients may develop coronary involvement or post-surgical stenosis 6, 7
• Consider mechanical valves cautiously in AS patients, as one case report documented exacerbation of AS and coronary stenosis post-mechanical valve implantation with cardiopulmonary bypass 6

Critical Hemodynamic Management During Evaluation

While confirming diagnosis and planning intervention 1, 8:

• Target systolic blood pressure 100-120 mmHg to maintain adequate perfusion without excessive afterload 1, 8
• Beta-blockers are preferred agents for blood pressure and heart rate control, as they reduce force of LV ejection 1, 8
• Avoid aggressive diuresis when LV cavity is small, as preload reduction can precipitate cardiovascular collapse 8
• Use vasodilators only with invasive hemodynamic monitoring in decompensated patients 8

Common Pitfalls to Avoid

• Do not perform AVR based solely on valve area <1.0 cm² with low gradients—confirmation of true severe AS is mandatory 2, 3
• Do not delay intervention once true severe AS is confirmed with contractile reserve—these patients have extremely poor prognosis without treatment 2, 3
• Do not assume all LFLG AS patients will benefit from surgery—those without contractile reserve have higher operative mortality and uncertain benefit 4
• In AS patients, do not overlook aortic root pathology—isolated valve replacement may be inadequate if significant aortitis or root dilation exists 5, 6, 7
• Do not proceed without Heart Valve Team evaluation—LFLG AS requires multidisciplinary assessment of technical feasibility, surgical risk, and expected outcomes 1