Primum Non Nocere: The Case for Watchful Waiting in Asymptomatic “Severe” Degenerative Mitral Regurgitation

Abstract

“ The physician must … have two special objects in view with regard to disease, namely, to do good or to do no harm ” — Hippocrates 1 The optimal surgical treatment for severe mitral regurgitation resulting from degenerative disease (flail or prolapse caused by myxomatous change or fibroelastic deficiency) is mitral repair.2–5 Although the decision to intervene on a symptomatic patient is relatively straightforward, current guidelines also define other triggers for surgery in patients who are asymptomatic.6,7 In the absence of symptoms, left ventricular (LV) dysfunction, defined as an LV ejection fraction (LVEF) of 30% to 60% or an LV end-systolic diameter (LVESD) of ≥40 mm6 (>45 mm7), is a class I indication. Class IIa indications in the asymptomatic patient with preserved LV function include atrial fibrillation and pulmonary hypertension (pulmonary artery systolic pressure >50 mm Hg at rest or >60 mm Hg after exercise). It is also deemed reasonable (class IIa6 or IIb7) to regard the presence of severe mitral regurgitation as a sole and sufficient indication for surgery provided that the likelihood of repair is high (≥90%)6 and operative risk is low.7 This last recommendation has generated considerable debate because no randomized controlled trial has defined the best treatment for asymptomatic patients with severe degenerative mitral regurgitation. Proponents of prophylactic repair favor an aggressive surgical approach, whereas opponents lobby for a strategy of close medical follow-up until conventional triggers are met (watchful waiting). Here, we present our argument for watchful waiting. Response by Enriquez-Sarano and Sundt see p 813 Because by definition a strategy of prophylactic surgery in asymptomatic patients cannot improve their sense of well-being, it must be associated with better surgical and/or clinical outcomes relative to a triggered strategy. It is our position that this benefit has …