• Review Concludes Valvular Interventions Are ‘Promising’ for MAC, but Warns Benefits Are Not Yet Established

    Mitral annular calcification (MAC)-related mitral valve (MV) dysfunction is increasing in prevalence in older populations and is associated with worse outcomes. However, valvular interventions demand careful discussion by a multidisciplinary heart valve team on the basis of dedicated anatomical imaging and patient goals of care, according to the latest JACC Review Topic of the Week.

    The review, published online Monday and in the Aug. 16 issue of the Journal of the American College of Cardiology, noted that while MAC is a common clinical finding that is associated with adverse clinical outcomes, the clinical impact of MAC-related MV dysfunction remains underappreciated.

    Led by Timothy W. Churchill, MD, from Massachusetts General Hospital, Harvard Medical School, Boston, the authors noted that data regarding MAC-related MV dysfunction are limited, warning that “significant challenges” exist in the diagnostic and therapeutic approach to patients – ranging from limitations of conventional echocardiographic assessment to ongoing controversy regarding clinical benefit of surgical or percutaneous treatment options in this high-risk population

    “Until recently, data on clinical outcomes in patients with MAC-related MV dysfunction have been limited, at least in part because of the absence of broadly accepted diagnostic criteria,” they noted. “Overall, though, the adverse prognosis associated with MAC-related MV dysfunction is well established.”

    Clinical data: Defining MAC

    Churchill and colleagues noted that a cohort of patients with MAC and mitral stenosis reported survival rates of 78% at 1 year, 47% at 5 years and 25% at 10 years, with worsening survival rates depending upon the severity of MV dysfunction.

    Similarly, they noted that a study following patients with stenotic, regurgitant, or mixed MV disease reported 1-year survival of 75%, 5-year survival of 40% and 10-year survival of 18% - with survival markedly impaired in the high-gradient (≥10 mm Hg) group (67% at 1 year 25% at 5 years and 11% at 10 years).

    “Within much of the spectrum of MAC-related MV dysfunction, additive MR [mitral regurgitation] on top of inflow obstruction appears to worsen outcome, as does the presence of comorbid valve disease such as aortic stenosis and tricuspid regurgitation,” said the reviewers.

    They noted that at present, however, there are no broadly accepted criteria for defining severity of MAC-related MV dysfunction.

    On the basis of currently available outcome data and the inclusion criteria in ongoing intervention studies (such as MITRAL II), the reviewers also propose a unifying definition of “severe” MAC-related MV dysfunction that integrates stenotic, regurgitant or mixed disease, as MVA <1.5 cm2 or more than moderate MR or transmitral gradient >8-10 mm Hg at a normal heart rate.

    Future perspectives for treatment

    The review team noted that the cornerstone of treatment of MAC-related MV dysfunction remains medical management with diuretic therapy and, if there is significant inflow obstruction, heart rate control with the goal of optimizing diastolic filling time.

    “Valvular interventions to directly address the valvular dysfunction, including surgery and transcatheter interventions such as valve-in-MAC and in limited circumstances edge-to-edge repair, are technically challenging and associated with a high degree of morbidity and mortality in this population,” they said.

    “Therefore, only a subset of patients will benefit from valvular intervention, and this assessment is based on integration of patient-specific anatomical considerations, comorbidity burden, and patient goals of care and should be discussed on a case-by-case basis by the multidisciplinary heart valve team.”

    Churchill and colleagues noted that in routine clinical practice, the patients with MAC to consider for referral to a comprehensive valve center are those with severe symptoms refractory to medical therapy, when symptoms are related to severe MAC-related valve dysfunction as based on an integrated clinical and imaging assessment.

    They noted that percutaneous transcatheter mitral valve replacement (valve-in-MAC) is a promising intervention, but warned that outcome benefit has not yet been established.

    “Prospective studies are needed to establish criteria for assessment of MAC severity and clinical risk stratification, clarify indications for intervention, and compare management strategies,” the reviewers said.

    “Looking ahead, a key path of future research will be to better define which patients are likely to benefit from the emerging array of valvular interventions,” they said. “This will require a greater ability to dissect the contribution of valvular dysfunction from the underlying comorbidity burden and ventricular abnormalities, as well as prospective randomized outcomes trials.”

    Sources:

    Churchill TW, Yucel E, Deferm S, et al. Mitral Valve Dysfunction in Patients With Annular Calcification: JACC Review Topic of the Week. J Am Coll Cardiol 2022;80:739-751.

    Image Credit: faustasyan – stock.adobe.com

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