{'fraction_non_alphanumeric': 0.027699530516431925, 'fraction_numerical': 0.018779342723004695, 'mean_word_length': 5.438066465256798, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 5, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Severe Aortic Stenosis Should Not Be Operated on Before Symptom Onset

> “If it ain't broke, don't fix it.” 
> 
> —Thomas Bertram Lance in Nation's Business , May 1977
Aortic valve stenosis resulting from calcific thickening of a previously normal 3-cusp aortic valve or a congenitally bicuspid aortic valve is a common clinical condition in developed countries, and its prevalence is continuing to increase with aging of the population.1,2 In the Cardiovascular Health Study, which involved 5201 men and women >65 years of age, the prevalence of aortic stenosis was 1.3% in subjects 65 to 75 years of age, 2.4% in subjects 75 to 85 years of age, and 4% in subjects >85 years of age.3 The precise mechanisms involved in the pathophysiology of aortic stenosis and its progression are incompletely understood, but advancing age and atherosclerosis-related risk factors have been implicated in the process.4 In fact, atherosclerotic coronary artery disease is present in nearly 50% of patients with aortic stenosis.5 Studies of valve pathology have suggested a potential role for dyslipidemia, inflammation, and angiogenesis in the process, but pharmacological therapies using statins to reduce dyslipidemia and associated inflammatory processes have yielded inconsistent but largely negative results in terms of reducing the rate of progression of aortic stenosis.6–10 Thus, in the absence of specific and effective disease-modifying medical therapies, surgical aortic valve replacement has been and continues to be the cornerstone of management of severe aortic stenosis. There is general agreement among physicians and surgeons that when severe aortic stenosis is accompanied by 1 or more symptoms, such as chest pain, syncope or near syncope, resuscitated sudden death, shortness of breath, fatigue, effort intolerance, or left ventricular (LV) dysfunction, aortic valve replacement is recommended because of well-established dismal outcome (≈50% mortality within 3 years) in unoperated symptomatic cases and overall excellent surgical outcomes with relatively low perioperative mortality and morbidity even among octogenarians …