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Asymptomatic Severe Aortic Stenosis
Acknowledgment
The authors acknowledge the contributions of Dr. Patrizio Lancellotti, who was the author of this chapter in the previous edition.
According to the guidelines, there are four stages of aortic stenosis (AS), which are differentiated by valve anatomy, hemodynamics, left ventricular (LV) dysfunction, and patient symptoms:
- A.
Stage A: at-risk anatomy, such as aortic sclerosis or bicuspid aortic valve
- B.
Stage B: progressive hemodynamic obstruction with mild or moderate AS
- C.
Stage C: severe asymptomatic AS
- D.
Stage D: severe symptomatic AS
Symptoms from AS include exertional dyspnea, angina, heart failure, presyncope, and syncope. Patients with symptomatic severe AS do poorly, and aortic valve replacement (AVR) whether surgical (SAVR) or transcatheter aortic valve replacement (TAVR), is indicated to improve survival, reduce symptoms, and improve exercise capacity. Currently, in asymptomatic severe AS, SAVR is recommended when:
- 1.
Left ventricular ejection fraction (LVEF) <50%
- 2.
“Very severe AS” with low surgical risk
- 3.
Rapidly progressing AS with low surgical risk
- 4.
The patient is undergoing another cardiac surgery
An outline of current guidelines recommendations for SAVR in asymptomatic AS can be found in Table 84.1 . Currently, there is no indication in the guidelines for TAVR in patients with asymptomatic severe AS. However, with the availability of less invasive techniques to treat patients with AS, including TAVR and minimally invasive AVR, and with reported poor outcomes associated with asymptomatic patients with AS, the decision of whether or not to undergo AVR is often debated. For patients with asymptomatic severe AS without another reason for AVR, stress testing is an important tool that can guide decision making on whether or not to perform AVR.
TABLE 84.1
Guidelines Comparison of American Heart Association/American College of Cardiology and European Society of Cardiology/European Association for Cardio-Thoracic Surgery
| Recommendations for SAVR in Patients with Asymptomatic Severe AS | AHA/ACC 2014/2017 COR | ESC/EACTS 2017 COR |
|---|---|---|
| Severe AS and LVEF ≤50% not due to other cause | I | I |
| Severe AS when undergoing other cardiac surgery | I | I |
| Abnormal exercise test showing symptoms related to AS | I | I |
| Very severe AS (aortic velocity ≥5.0 m/s) and low surgical risk | IIa | |
| Very severe AS (aortic velocity ≥5.5 m/s) and low surgical risk | IIa | |
| Exercise test showing exercise decrease in BP | IIa | IIa |
| Exercise test showing decreased exercise tolerance | IIa | |
| Rapid disease progression (V max ≥0.3 m/s/year) and low surgical risk | IIb | IIa |
| Elevated BNP (>3 times age- and sex-corrected normal range) confirmed by repeated measurements without further explanation | IIa | |
| Severe pulmonary hypertension (PASP at rest >60 mm Hg on invasive measurement) without other explanation | IIa |
AHA/ACC, American Heart Association/American College of Cardiology; AS, aortic stenosis; BP, blood pressure; BNP, B-type natriuretic peptide; COR, Class of Recommendation; ESC/EACTS, European Society of Cardiology/European Association for Cardio-Thoracic Surgery; LVEF, left ventricular ejection fraction; PASP, pulmonary artery systolic pressure; SAVR, surgical aortic valve replacement; V max , maximum transvalvular flow velocity.
Natural History of Asymptomatic Severe Aortic Stenosis
Of more than 3800 patients analyzed in the Contemporary Outcomes After Surgery and Medical Treatment in Patients With Severe Aortic Stenosis (CURRENT AS) Registry, approximately 50% were asymptomatic when diagnosed with severe AS. Although patients with asymptomatic severe AS have a low risk of sudden cardiac death at 1% to 1.5% per year, AS is a chronic and progressive disease that does not carry a benign prognosis. , On average:
- 1.
Aortic jet velocity increases 0.3 m/s/year.
- 2.
Mean gradient increases 7 mm Hg per year.
- 3.
AVA decreases 0.1 cm 2 per year.
However, hemodynamic progression has been shown to be highly variable, and death in this population is associated with the severity and rate of AS progression. , Retrospective database analysis demonstrated rates of AVR or cardiac death to be 20%, 37%, and 75% at 1, 2, and 5 years, respectively. Zilberszac and colleagues prospectively followed 103 patients with asymptomatic severe AS older than 70 years of age with transthoracic echocardiography (TTE) and clinical evaluation of symptoms. Indications for AVR or cardiac death were observed in 27%, 57%, 77%, and 84% of patients at 1, 2, 3, and 4 years, respectively. Of the patients who developed symptoms during follow-up, 43% experienced severe onset of symptoms (New York Heart Association Class III or IV). The patients with severe symptom onset had a higher postoperative mortality rate than the patients with mild onset of symptoms. Twenty-nine percent of patients had a medical comorbidity limiting mobility, which highlights the difficulty in determining AS symptoms in this patient population. This data confirms the poor prognosis of AS in asymptomatic patients.
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