Prognosis

For patients with mild or moderate stenosis, the aortic valve area decreases on average by 0.1 cm²/year and the mean gradient increases by 7 mmHg annually.[78] It is recommended that patients with moderate AS have an echocardiogram every 1 to 2 years, and those with mild AS have one every 3 to 5 years.[26] It is important to note that the rate of progression is extremely variable and so the recommended follow-up periods may vary between individuals.

The onset of symptoms is a significant milestone and portends a poor prognosis, with an average survival of only 2 to 3 years without surgery. Between 8% and 34% of symptomatic patients die suddenly.[79] It is thus essential that symptomatic patients be referred for surgical aortic valve replacement.

Surgical replacement of the aortic valve is extremely effective therapy. Advances in prosthetic-valve design, cardiopulmonary bypass, surgical technique, and anaesthesia have steadily improved outcomes for aortic valve surgery. An analysis of the 2006 American Society of Thoracic Surgery STS database shows that during the previous decade, the mortality risk of isolated aortic valve replacement decreased from 3.4% to 2.6%. For those <70 years at surgery, the mortality risk is 1.3%.[46] Patients who survive surgery have near-normal life expectancy, with relative survival at 5, 10, and 15 years of 99%, 85%, and 82%, respectively.[80][81] Nearly all patients have improvement in ejection fraction and heart failure symptoms, with the most significant benefit seen in those with more advanced preoperative symptoms.[82][83] For those who do not improve, factors to consider are valve dysfunction, less-than-expected improvement in preoperative left ventricle function, valve-prosthesis mismatch, and other comorbid conditions.

Appropriately selected patients at all levels of surgical risk may be offered surgery or transcatheter aortic valve replacement (TAVR), while patients with prohibitive risk (i.e., surgical non-candidates) should be referred for TAVR if predicted post-TAVR survival is greater than 12 months.[59][26] In the PARTNER study comparing surgery and TAVR in high-risk patients, mortality and symptom reduction were similar at 2 and 5 years for each modality.[52][53] Peri-procedural risks varied at 30 days; vascular complications and neurological events such as stroke occurred more frequently after TAVR, while major bleeding and new-onset atrial fibrillation more commonly followed surgery.[54]​​[55] Acute kidney injury and new pacemaker implantation were complications of both interventions at similar rates.[54]​ At 2 and 5 years, echocardiographic improvements in valve area and mean gradients were similar in both groups, but total and paravalvular aortic regurgitation was encountered more frequently after TAVR.[52][53][57] In patients with prohibitive surgical risk (i.e., surgical non-candidates), the PARTNER trial compared standard therapy, including balloon aortic valvuloplasty, with TAVR and found a 20% absolute reduction in mortality at 1 year in favour of TAVR.[60] At 3 years, mortality with TAVR was 54.1% compared with 80.9% with standard therapy, while at 5 years, mortality was 71.8% and 93.6%, respectively.[61][62] Heart failure symptoms improved between 30 days and 6 months, while at 3 years 29.7% of patients in the TAVR group were alive with New York Heart Association Class I/II symptoms, compared with 4.8% of patients in the standard therapy group.[60][61][63] Patients treated with TAVR also showed significant improvements on assessments of health-related quality of life when compared with those receiving standard therapy.[64]

Many patients with bicuspid aortic valves will require valve replacement at some point in their lives. After valve replacement, patients with bicuspid valves have a significant mortality benefit and improvement in symptoms. However, they remain at risk for aortic dissection and require serial follow-up for this potential complication.

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