ACC/AHA Guidelines and Treatment Options for Mitral Valve Disease

INTRODUCTION

Guidelines and recommendations for the treatment of valvular syndromes are periodically published by the American College of Cardiology (ACC) and the American Heart Association (AHA). In this chapter we will review the mitral valve (MV) recommendations from the 2020 ACC/AHA Guideline for the Management of Patients with Valvular Heart Disease and discuss differences compared to the 2021 European Society of Cardiology/European Association for Cardio-Thoracic Surgery (ESC/EACTS) Guidelines for the Management of Valvular Heart Disease.

ACC/AHA strength of recommendations are assigned Class I (strong), Class IIa (moderate), Class IIb (weak), Class III (no benefit), and Class IIIb (harm), whereas in the ESC the divisions are worded slightly differently: Class I (recommended), Class IIa (should be considered), Class IIb (may be considered), and Class III (is not recommended). The ACC/AHA Levels of Evidence are categorized as A (high quality), Level B-R (moderate quality), Level B-NR (nonrandomized moderate quality), Level C-LD (limited data), and Level C-EO (expert opinion), whereas in the ESC they are again slightly different, with Level A (multiple randomized control trials [RCTs]), Level B (single RCT or large nonrandomized studies), and Level C (expert opinion or small studies).

Criteria for determining severity of, and recommendations for, MV syndromes are discussed in a different chapter and include additional factors aside from valve function, such as comorbidities, surgical risk, and cardiac and extra-cardiac end-organ damage. Accordingly, guidelines will not only involve active surgical or interventional treatments, but also include conservative management, watchful waiting, periodic monitoring, and postprocedural care. Therefore, guidelines stress thorough initial and subsequent evaluations ought to be performed in order to continuously optimize and individualize treatment. Evaluation should encompass establishing the stage of the disease ( Table 3.1 ), which takes into account symptomatology, physical examination, anatomy, severity, response of the ventricle and pulmonary circulation, and results of noninvasive and invasive testing as indicated. Finally, candidates for interventions should be evaluated by a multidisciplinary heart valve team (MDT) (recommendation I, Level C-EO).

In a patient who is a candidate for intervention, risks should be calculated and discussed (recommendation I, Level C-EO) using an outcome score. In the US, the Society of Thoracic Surgeons (STS) score is most commonly used, although the European System for Cardiac Operative Risk Evaluation (EuroSCORE) II can also be considered ( Table 3.2 ). A high surgical risk patient is, strictly speaking, defined as having an STS score above 8% for mortality. Other important determinations of surgical risk not necessarily accounted for in the surgical risk scores include two or more frailty indices of moderate-to-severe frailty (indices such as Katz Activities of Daily Living, and independence in ambulation), a major organ system compromise (cardiac or extra-cardiac) that is predicted not to improve postoperatively, or possible procedure-specific considerations, including the presence of tracheostomy, porcelain ascending aorta, chest malformation, arterial coronary graft adherent to posterior chest wall, prior sternotomy, severe chronic obstructive pulmonary disease (COPD), pulmonary hypertension, and hepatic dysfunction and radiation damage. Prohibitive surgical risk is defined as STS score above 50% for mortality or major morbidity, two or more frailty indices of moderate-to-severe frailty, three or more major organ system compromise that is predicted not to improve postoperatively, or severe procedure-specific impediments. Finally, multivalvular disease must be assessed, and indicators of futility, such as STS score for mortality over 15%, life expectancy of less than 1 year, and a poor candidate for rehabilitation, should also be considered.

MITRAL REGURGITATION

Over the years, guidelines have had to accommodate the progression in therapeutic options as new technologies have emerged. Threshold for nonsurgical interventions is continuously lowered since there is less impact of traditional comorbidities on outcomes, and with greater technical expertise, better patient selection, and generational device improvements procedural complications have generally declined and clinical outcomes improved. Percutaneous therapies such as the U.S. Food and Drug Administration (FDA)-approved edge-to-edge repair, as well as current investigational valve implantation, annuloplasty, and technologies aiming at chordae repair strategies, have substantially impacted management of patients with mitral regurgitation (MR) in clinical practice. Aims of invasive treatment include alleviation of symptoms, interrupting the vicious cycle of left ventricular (LV) volume overload and its sequalae, and improving mortality outcomes.

MR can be divided into acute and chronic, and treatment options vary accordingly and may be influenced by the specific etiology of MR. A further mechanistic division, which is more relevant to the chronic MR, includes primary and secondary MR.