The primary indication for intervention is symptomatic (stage D) severe AS, which is typically characterized by echocardiographic peak flow velocity (V_max) ≥4 m/s, mean gradient (MG) of ≥40 mm Hg, or an aortic valve area (AVA) ≤1.0 cm². However, there are actually three defined stages of symptomatic, severe AS by echocardiographic criteria. Stage D1 is high-gradient AS with V_max of ≥4m/s, MG of ≥40 mm Hg, and AVA ≤1.0 cm². D2 is commonly referred to as low-flow, low-gradient AS and is characterized by V_max ≤4 m/s, MG of ≤40 mm Hg, and AVA of ≤1.0 cm² with reduced left ventricular ejection fraction (LVEF < 50%). Stage D3 is low-gradient with normal LVEF or paradoxical low flow with AVA of ≤1.0 cm², V_max ≤4 m/s or MG of ≤40 mm Hg, indexed AVA ≤0.6 cm²/m², or stroke volume index <35 mL/m².

Typical symptoms of severe stenosis are syncope or presyncope by history or on exercise testing, exertional dyspnea, reduced exercise tolerance, angina, and heart failure. Indications for aortic valve surgery are summarized in Table 87.1.

When deciding upon surgical aortic valve replacement (SAVR) versus transcatheter aortic valve replacement (TAVR), a comprehensive Heart Valve Team should aid in the candidacy for either approach. The Heart Team is usually integrated by cardiac surgery, cardiology, interventional cardiology, and cardiac anesthesia.³ The decisions are made based on the Society of Thoracic Surgeons (STS) predicted risk of mortality, with intermediate risk being 4% to 8% and high risk ≥8%, patient frailty, comorbid conditions, and patient preference. The indications for TAVR are rapidly changing with evolving technologies and mounting TAVR long-term data.⁴,⁵ Primary recommendations are (1) surgical SAVR for patients who meet aortic valve replacement (AVR) indications with low or intermediate surgical risk; (2) TAVR or high-risk SAVR in high surgical risk patients based on Heart Team assessment; and (3) TAVR is recommended in patients with prohibitive surgical risk and/or a predictive postprocedure survival of more than 12 months. TAVR is a reasonable alternative (Class IIa) in patients with severe AS and intermediate surgical risk based on the Heart Team assessment. Percutaneous aortic balloon dilation may be considered (Class IIb) as a bridge to SAVR or TAVR in patients with severe AS who are severely symptomatic or need a delay in definitive therapy for other reasons.

Indications for intervention depend on the acuity of aortic regurgitation (AR). Acute AR secondary to aortic dissection or infective endocarditis is a surgical emergency, and early AVR results in better outcomes.¹,⁶ Patients may present with hypotension, systemic hypoperfusion, and/or pulmonary edema. Chronic AR can present with symptoms of angina, exertional dyspnea, or heart failure symptoms. Severe AR characteristics include jet width more than 65% of left ventricular outflow tract, vena contracta greater than 0.60 cm, holo-diastolic flow reversal in the proximal abdominal aorta, regurgitant volume greater than or equal to 60 mL/beat, regurgitant fraction greater than or equal to 50%, effective regurgitant orifice area (EROA) ≥0.30 cm², angiography grade 3+ to 4+, and left ventricular dilation. Recommendations for aortic valve surgery are summarized in Table 87.1. Surgical AVR is the treatment for AR; however, a growing number of reports in the literature demonstrate TAVR as a potential therapy in highly selected cases.

The choice of valve type for each patient includes a number of factors, many of which are nonmedical. For patients younger than 50 years and able to take chronic anticoagulation, mechanical valves are generally preferred.⁷,⁸ For those older than 70 years, bioprosthetic valves are recommended. For those with occupations or hobbies that prohibit anticoagulants, or patients unable to take anticoagulation routinely, bioprosthetic valves should be considered. For women of childbearing age, the risk of fetal complications associated with chronic anticoagulation for a mechanical valve needs to be weighed against the rapid deterioration that may occur with a bioprosthesis. With the approval of TAVR for valve-in-valve replacement, the age at which more bioprosthetic valves than mechanical valves are used is decreasing rapidly.⁹