From the Guidelines
Severe aortic stenosis can indeed cause syncope, as evidenced by the 2024 AHA/ACC/ACS/ASNC/HRS/SCA/SCCT/SCMR/SVM guideline for perioperative cardiovascular management for noncardiac surgery 1.
Definition and Symptoms
Severe aortic stenosis is defined as an aortic valve area < 1.0 cm2, mean aortic valve gradient ≥ 40 mm Hg, or peak aortic valve velocity Vmax ≥ 4.0 m/s, and symptoms include exertional dyspnea, angina, heart failure, syncope, or presyncope.
Pathophysiology and Clinical Implications
Syncope in severe aortic stenosis occurs when the narrowed aortic valve prevents adequate blood flow from the heart to the body, particularly during physical exertion or stress, resulting in decreased blood flow to the brain and temporary loss of consciousness.
Management and Treatment
The presence of syncope in a patient with aortic stenosis often indicates the need for urgent valve replacement, either through surgical aortic valve replacement (SAVR) or transcatheter aortic valve replacement (TAVR), as the risk of sudden cardiac death increases significantly once syncope develops, as recommended in the guideline 1. Key points to consider in managing patients with severe aortic stenosis and syncope include:
- Monitoring closely to avoid hypotension, excessive hypertension, and tachycardia
- Considering balloon aortic valvuloplasty as a bridging strategy in patients who require urgent elevated-risk noncardiac surgery
- Shared decision-making with the patient and family in high-risk or otherwise challenging settings Patients experiencing syncope should seek immediate medical attention, as prompt treatment can significantly improve outcomes and reduce the risk of morbidity and mortality 1.
From the Research
Severe Aortic Stenosis and Syncope
- Severe aortic stenosis (SAS) can cause syncope, as evident from various studies 2, 3, 4, 5, 6
- Syncope is one of the cardinal symptoms of SAS, along with angina and symptoms of heart failure 3, 4
- The presence of syncope in patients with SAS is associated with a higher risk of mortality after surgical aortic valve replacement (SAVR) 4
Etiologies of Syncope in Severe Aortic Stenosis
- Syncope in patients with SAS can be caused by various mechanisms, including:
- In some cases, the exact cause of syncope may remain unknown, which can be associated with increased mortality 5
Prognostic Significance of Syncope
- Syncope can be a prognostic indicator of poor outcomes in patients with SAS, particularly after SAVR 4
- However, the presence of syncope before transcatheter aortic valve replacement (TAVR) may not have a significant prognostic impact on patients undergoing TAVR 6
- Accurate diagnosis of the cause of syncope is crucial, as it can have important clinical implications 5