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    Interventional procedure overview of off-pump minimal access mitral valve repair by artificial chordae insertion to treat mitral regurgitation

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    Outcome measures

    The main outcomes included success endpoints, reduction in MR, functional outcomes, echocardiographic outcomes, mortality and complications. The measures used are detailed in the following paragraphs. A number of the included studies have performed additional analyses comparing endpoints among groups based on preoperative MV anatomy as follows: Type A, isolated central PML prolapse and/or flail; Type B, posterior multi-segment prolapse and/or flail; Type C, anterior or bileaflet prolapse and/or flail; Type D, paracommissural prolapse and/or flail or any type of disease with the presence of significant leaflet and/or annular calcifications.

    MR grade

    There are several classification systems of MR based on imaging. This is usually based on echocardiography, but angiography and MRI can also be used. In the included studies, MR grade was classified based on a range of objective guidelines including ASE, AHA, and ESC. Classification has 5 grades ranging from none to 1+ (mild MR), 2+, 3+, or 4+ (severe MR). A simplified 3 grade classification system is sometimes used (mild, moderate, or severe).

    New York Heart Association (NYHA) functional class

    The NYHA functional class is used to classify heart failure according to severity of symptoms and limitation of physical activity:  

    • Class 1 - no limitation of physical activity. Ordinary physical activity does not cause undue fatigue, breathlessness, or palpitations.  

    • Class 2 - slight limitation of physical activity. Comfortable at rest but ordinary physical activity results in undue breathlessness, fatigue, or palpitations.  

    • Class 3 - marked limitation of physical activity. Comfortable at rest but less than ordinary physical activity results in undue breathlessness, fatigue, or palpitations.  

    • Class 4 - unable to carry out any physical activity without discomfort. Symptoms at rest can be present. If any physical activity is undertaken discomfort is increased.  

    Echocardiographic outcomes

    Some studies reported echocardiographic measurements, including linear dimensions and volumes. Other outcomes are described in the following paragraphs.  

    LVEF is the ratio of blood ejected during systole (stroke volume) to blood in the left ventricle at the end of diastole (end-diastolic volume). A normal range is typically between 50 and 70%. Values below 30% are considered a severe reduction. 

    LVEDVi is the volume of blood in the left ventricle at the end of diastole, just before the heart contracts (systole). It is indexed to adjust for a person's body surface area, enabling comparison across people of different sizes. The normal range is between 30 and 79 ml/m2.

    LVESVi is the volume of blood remaining in the ventricle after the heart contracts (systole). It is indexed to adjust for a person's body surface area, enabling comparison across people of different sizes. The normal range is between 9-31 ml/m2.

    LAVi is the volume of the left atrium at the end of systole. It is indexed to adjust for a person's body surface area, enabling comparison across people of different sizes. A normal value is 34ml/m2 or lower.

    sPAP is the pressure in the pulmonary artery during the systolic phase. The normal range is between 18 and 25mmHg.

    MVARC endpoint definitions

    Technical success (measured at exit from the catheterisation laboratory):

    • Absence of procedural mortality

    • Successful access, delivery, and retrieval of the device delivery system

    • Successful deployment and correct positioning of the first intended device

    • Freedom from emergency surgery or reintervention related to the device or access procedure.

    Device success (measured at 30 days and at all later post-procedural intervals):

    • Absence of procedural mortality or stroke

    • Proper placement and positioning of the device

    • Freedom from unplanned surgical or interventional procedures related to the device or access procedure

    • Continued intended safety and performance of the device, including:

      • No evidence of structural or functional failure

      • No specific device-related technical failure issues and complications

      • Reduction of MR to either optimal or acceptable levels

    Procedural success (measured at 30 days):

    • Device success (either optimal or acceptable)

    • Absence of major device or procedure related serious adverse events, including:

      • Death

      • Stroke

      • Life-threatening bleeding

      • Major vascular complications

      • Major cardiac structural complications

      • Stage 2 or 3 acute kidney injury (includes new dialysis)

      • Myocardial infarction or coronary ischaemia requiring percutaneous coronary intervention or coronary artery bypass graft.

      • Severe hypotension, heart failure, or respiratory failure requiring intravenous pressors or invasive or mechanical heart failure treatments

      • Any valve-related dysfunction, migration, thrombosis, or other complication requiring surgery or repeat intervention

    Patient success (measured at one year):

    • Device success (either optimal or acceptable)

    • Patient returned to the pre-procedural setting

    • No rehospitalizations or reinterventions for the underlying condition

    • Improvement from baseline in symptoms

    • Improvement from baseline in functional status

    • Improvement from baseline in quality-of-life

    Clinical assessment tools

    Most studies used a scoring system for assessing the risk of in-hospital mortality after cardiac surgery. The main ones are described below:

    EuroScore II

    EuroScore II is a validated and commonly used risk model for assessing the perioperative risk of mortality after major cardiac surgery. It is based on patient factors, such as age, sex and comorbidities, cardiac specific factors, such as NYHA class, and procedural factors, such as urgency. It is expressed as a percentage on a scale of 0 to 100%, with lower scores indicating a lower risk.

    STS Score

    The STS score is a risk stratification model, composed of up to 30 variables that predict short- and long-term mortality and morbidity after cardiac surgery. In general, an STS predicted risk of surgical mortality of 4 to 8% is considered intermediate risk and 8% or greater is considered high risk. Some studies report an STS-PROM MV score, which estimates the predicted risk of mortality at 30 days after isolated mitral valve repair (range, 0%-100%; a higher score indicates an increased risk).