Chapter 21: Transcatheter Aortic Valve Replacement

PATIENT CASE

An 88-year-old man with a history of hypertension, insulin-dependent diabetes mellitus, moderate chronic obstructive pulmonary disease, and coronary artery disease with a remote inferior myocardial infarction was recently hospitalized for decompensated heart failure. He reported dyspnea with mild exertion while walking on level ground and associated substernal chest pressure consistent with New York Heart Association class III heart failure. He also reported 2-pillow orthopnea and progressive lower extremity edema. The physical exam demonstrated a grade III/VI late-peaking systolic crescendo-decrescendo murmur with obscuration of the second heart sound. The carotid upstrokes were blunted and delayed. The jugular venous pressure was estimated at 12 cm above the right atrium. A transthoracic echocardiogram demonstrated normal left ventricular function with an ejection fraction of 55% and a calcified trileaflet aortic valve with reduced leaflet mobility. Doppler interrogation of the aortic valve demonstrated a peak systolic velocity of 4.2 m/s and a mean systolic gradient of 45 mm Hg. The aortic valve area, calculated by the continuity equation, was found to be 0.8 cm². Based on the physical exam and echocardiography findings consistent with severe aortic stenosis, his predicted risk of mortality with surgical aortic valve replacement at 30 days was 11.5%.

AORTIC STENOSIS

Per the 2014 American Heart Association and American College of Cardiology (ACC) guidelines for the management of valvular heart disease, severe high-gradient aortic stenosis is defined as a peak aortic valve velocity greater than 4.0 m/s, a mean aortic valve gradient greater than 40 mm Hg, an aortic valve area of less than 1.0 cm², and an indexed aortic valve area of less than 0.6 cm²/m².¹

Calcific aortic stenosis is the most common form of acquired valvular heart disease in the United States that affects primarily older individuals, with a prevalence of 25% to 29% in patients older than age 65 years and 37% in those older than age 75 years.^2–4 Moderate to severe aortic stenosis develops in approximately 1.3% of those age 65 to 75 years and 2.8% of those older than age 75 years.⁵ Furthermore, the prevalence of aortic stenosis is likely to increase in the future as it is estimated that by 2020 there will be 20 million Americans older than age 80.⁶

Clinically, aortic stenosis is an insidious and progressive disease that develops over decades and has a long latency period prior to the development of symptoms.⁷ Compared to aged-matched asymptomatic controls, there is no difference in outcomes in patients with asymptomatic aortic stenosis.⁴ However, as described in 1968, once symptoms develop from aortic stenosis, the median survival is poor, at just 2 to 3 years.⁷ The classic triad of symptoms from aortic stenosis includes exertional angina, syncope, and dyspnea, with a median survival of 5 years when angina develops, 3 years when syncope develops, and 2 years ...