Mitral Regurgitation and Aortic Stenosis: Prevalent and Progressive Valve Diseases

THE GROWING PREVALENCE OF AORTIC STENOSIS AND THE LATEST THERAPY GUIDELINES

Aortic Valve Stenosis Overview

Aortic stenosis represents 34% of the native valvular diseases in industrialized nations, and is the most common primary valve disease requiring surgery or transcatheter intervention in Europe and North America.1,2 Of the 146,304 deaths in the U.S. from aortic valve disease (ICD-10 data from 1999 to 2009), 82.7% were from aortic stenosis.3

Due to the aging population, aortic stenosis prevalence is growing: the number of elderly patients with calcific aortic stenosis is projected to more than double by 2050 in both the U.S. and Europe.3

    Aortic Stenosis Statistics

    From the onset of symptoms, risk of mortality from aortic valve stenosis is approximately 25% at 1 year and 50% at 2 years if patients, who are already medically treated, do not undergo aortic valve replacement–this is because replacement is the only effective treatment.4,5

    Among this same patient subset, more than 50% of deaths are sudden cardiac deaths.4 It is theorized that the fatal arrhythmias that preced aortic valve stenosis are secondary to inadequate blood flow through the aortic valve into the coronary arteries.6

    Each year, approximately 90,000 aortic valve prostheses are implanted in the U.S. Worldwide, the figure is 280,000, and by 2050 the number is expected to reach 850,000 annually.7

    Referrals to Cardiovascular Specialists

    Due to enhanced awareness of various treatments, referring physicians are sending more patients with valve disease to cardiovascular specialists, where they can offer patients improved noninvasive imaging tests and greater expertise in interventions. When patients with valve disease are referred for intervention in a timely manner, they experience better outcomes in terms of preserved ventricular function as well as survival rates.

    TYPES of Aortic Stenosis

    There are 4 stages of aortic stenosis:5

    • Stage A: at risk of stenosis
    • Stage B: with progressive hemodynamic obstruction
    • Stage C: with severe asymptomatic stenosis
    • Stage D: with symptomatic stenosis

    There is an additional category of “very severe” stenosis based on studies of the natural history of the disease, showing that prognosis becomes poorer as the severity of stenosis increases, and the event-free survival can be 50% at 2 years.

    Consequently, patients with asymptomatic severe aortic stenosis require frequent monitoring for progression because symptom onset may be insidious and not well recognized by the patient. An increase in hemodynamic severity is inevitable once even mild stenosis is present.

    Risk Factors

    Regarding Stage A, there are certain patient characteristics that reflect risk factors for progression of aortic stenosis, including baseline valve area, degree of valve calcification, older age, history of smoking, and male sex. Other risk factors include presence of bicuspid vs tricuspid involvement, coronary artery disease, mitral annular calcification, hypercholesterolemia, higher body mass index, renal insufficiency, hypercalcemia, metabolic syndrome, and diabetes.3

    Pathophysiology of Aortic Stenosis

    Elevated left ventricular systolic blood pressure accompanies aortic stenosis, yet compensatory mechanisms include LV hypertrophy and atrial augmentation of preload—so cardiac output can be maintained for many years. As the disease worsens, these adaptations become inadequate and the patient may eventually develop symptoms of decreased cardiac output and heart failure.4

    SYMPTOMS OF AORTIC STENOSIS–SIGNALING NEED FOR AORTIC VALVE REPLACEMENT

    Due to the often slow, progressive nature of aortic stenosis, patients may not recognize symptoms because they may have gradually limited their daily activity levels. Typical initial symptoms are dyspnea on exertion or decreased exercise tolerance.5

    Most patients with aortic stenosis are first diagnosed when cardiac auscultation reveals a systolic murmur; there also tends to be diminished or absent A2. Patient symptoms which are late manifestations of the disease include:4

    • Angina pectoris typically upon physical exertion
    • Heart failure symptoms such as paroxysmal nocturnal dyspnea, orthopnea, dyspnea on exertion, and shortness of breath
    • Syncope, often upon exertion when systemic vasodilatation in the presence of a fixed forward stroke volume causes the arterial systolic blood pressure to drop
    • Systolic hypertension

    Asymptomatic patients with severe aortic stenosis should be re-evaluated at least every 6 months to determine if there is a change in symptoms such as exercise tolerance.2

    Intervention: SAVR and TAVR

    There are many new developments in the field of aortic valve disease related to patients’ natural history, advances in diagnostic imaging, and improvements in catheter-based and surgical interventions.8 Transcatheter aortic valve replacement (TAVR) is now considered an effective therapy in patients for whom surgery is not an option, as well as an alternative for high-risk patients.9

    The strongest indication for intervention is the presence of symptoms. In patients with severe, symptomatic, and calcific aortic stenosis, the only effective treatment is surgical aortic valve replacement (SAVR) or TAVR—since there is a high risk of death if valve replacement is not performed.5

    Even otherwise healthy patients with severe, symptomatic stenosis should nearly always be considered for intervention.5

    The choice of proceeding with SAVR vs TAVR is based on multiple factors, including the surgical risk, comorbidities, patient frailty, and patient preferences.8

    The Increase in TAVR Procedures: Primarily Patients Otherwise Untreated

    Since its initial approval in the U.S. in November 2011, TAVR has increased markedly: 4,627 procedures in 2012, 34,892 in 2016, and nearly 90,000 total procedures during that time frame.10 TAVR patients are typically older (median age 83 years)10 and at higher procedural risk than those undergoing SAVR—in other words, patients who otherwise may not have received surgical treatment due to their age and risk profile.

    Data from the U.S. revealed that the initial length of stay was an average of 4.4 days shorter for patients treated with TAVR compared to SAVR. TAVR also reduced the need for rehabilitation services at discharge and was associated with improved 1-month quality-of-life indicators.3

    Medical Therapy for Aortic Stenosis

    For aortic stenosis patients, medical therapy cannot improve outcomes compared with the natural history of the disease.

    2017 Updates to the AHA/ACC Valvular Heart Disease Guidelines

    Major areas of change include indications for TAVR procedures. The latest guidelines include:8

    SAVR and TAVR

    • Recommending either SAVR—or TAVR among high-risk patients—in those with severe, symptomatic aortic stenosis (stage D), after consideration by a heart valve team (now Class I vs Class IIa previously)
    • Stating that TAVR is a reasonable alternative to SAVR for patients with severe, symptomatic aortic stenosis (stage D) and intermediate surgical risk

    TAVR Valve-in-Valve

    • Stating that a transcatheter valve-in-valve procedure is reasonable for severely symptomatic patients—with either bioprosthetic aortic valve thrombosis stenosis or bioprosthetic aortic valve regurgitation—who are assessed by the heart valve team to be at high or prohibitive surgical risk

    Anticoagulation

    • Combining into 1 recommendation that anticoagulation for all surgical tissue prostheses should be for up to 6 months, due to lower stroke risk and lower mortality rate in patients on a 6-month regimen vs no anticoagulation
    • For the mechanical On-X AVR only: lowering the target international normalized ratio (INR) to 1.5-2.0 for patients with no thromboembolic risk factors, since the bleeding rate in the control group was unusually high

    Imaging

    • Combining multiple imaging recommendations into 1: in patients with suspected mechanical prosthetic valve thrombosis, multimodality imaging with transthoracic echocardiography (TTE), transesophageal echocardiography (TEE), fluoroscopy, and/or computed tomography (CT) scanning may be more effective than one imaging modality alone in detecting and characterizing valve thrombosis, since it is necessary to evaluate valve function, leaflet motion, and extent of thrombus

    Mechanical or Bioprosthesis

    • Expanding the age—now age 50-70 vs age 60-70—regarding the Class IIa indication for patients undergoing aortic mechanical or bioprosthetic replacement
    • Stating that the choice of type of prosthetic heart valve should be a shared decision-making process that accounts for the patient’s values/preferences and includes discussions about anticoagulant therapy and the potential need for and risk associated with reintervention (now “reintervention” vs “reoperation”)

    Bicuspid Aortic Valve

    Most patients with a bicuspid aortic valve will develop aortic stenosis or aortic regurgitation over their lifetime. In 20%-30% of patients with bicuspid valves, other family members also have bicuspid valve disease and/or a related aortic abnormality. There are no proven drug therapies that have been shown to reduce the rate of progression of aortic dilation in patients with aortopathy associated with bicuspid aortic valve.5

    Treatment Options for AORTIC Valve Disease

    Treatment Options for Aortic Valve Disease

    Various Abbott products offer effective treatment for aortic valve disease.
     

    TrifectaTM GT Tissue Valve for Aortic Valve Replacement

    RegentTM Mechanical Valve for Aortic Valve Replacement


    The information provided is not intended for medical diagnosis or treatment as a substitute for professional advice.  Consult with a physician or qualified healthcare provider for appropriate medical advices.

    AP2947064-WBU Rev. A

    References
    1. Capoulade R, et al. Assessment of aortic valve disease: role of imaging modalities. Curr Treat Options Cardio Med. 2015;17: 49. doi: 10.1007/s11936-015-0409-7.
    2. Baumgartner H, et al. 2017 ESC/EACTS Guidelines for the management of valvular heart disease. Eur Heart J. 2017;38:2739–2791. doi:10.1093/eurheartj/ehx391.
    3. Benjamin EJ, et al. Heart disease and stroke statistics—2018 update: a report from the American Heart Association. Circulation. 2018;137(12):e67-e492. doi: 10.1161/CIR.0000000000000558.
    4. Ren X. Aortic stenosis. MedScape. https://emedicine.medscape.com/article/150638-overview. Published March 23, 2017.
    5. Nishimura RA, et al. 2014 AHA/ACC Guideline for the management of patients with valvular heart disease. Circulation. 2014;129(23):2440-2492. doi: 10.1161/CIR.0000000000000029.
    6. Kulick DL. Aortic valve stenosis symptoms, treatment, types, and surgery. MedicineNet. https://www.medicinenet.com/aortic_stenosis/article.htm. Reviewed November 13, 2017.
    7. Zenses AS, et al. Prosthetic aortic valves. Encyclopedia of Biomedical Engineering. 2018. doi.org/10.1016/B978-0-12-801238-3.11103-1. Accessed September 17, 2018.
    8. Nishimura RA, et al. 2017 AHA/ACC focused update of the  2014 AHA/ACC Guideline for the management of patients with valvular heart disease. Circulation. 2017;135:e1159–e1195. doi: 10.1161/CIR.0000000000000503.
    9. Reinöhl J, et al. Effect of availability of transcatheter aortic-valve replacement on clinical practice. N Engl J Med. 2015;373(25):2438-2447. doi: 10.1056/NEJMoa1500893.
    10. Messenger, C. John. Trends in United States TAVR Practice.  Cardiac Interventions Today. March/April 2018.
       

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