Acute mitral regurgitation complicating STEMI

Abstract

Abstract Funding Acknowledgements None. Introduction Acute ischemic mitral regurgitation (aiMR) occurs in 17-40% of patients suffering an acute coronary syndrome. Although severe forms constitute less than 1% of the cases, this complication significantly increases mortality risk. While surgery has been traditionally considered the treatment of choice, heterogeneity in underlying mechanisms and lack of updated evidence questions optimal treatment. Purpose The aim of the present study was to describe baseline clinical characteristics, management and outcomes of a contemporary cohort of patients with aiMR. Methods A retrospective cohort including patients diagnosed with moderate to severe aiMR presenting from 2006 to 2019 at the National Institute of Cardiology "Ignacio Chavez" in Mexico City. Results A total of 10,434 patients presented to the study center with an ACS from 2006 to 2019, out of which 6,448 (61.8%) were diagnosed with STEMI and 3,986 (38.2%) with NSTEMI. Mechanical post-infarction complications occurred in 203 (1.9%). Among these, aiMR was observed in 132 patients (1.3%), categorized as moderate in 49 patients (37.2%) and severe in 83 patients (62.8%). 6 patients were excluded due to incomplete information. Acute ischemic mitral regurgitation was more frequent in patients with STEMI (79.4%) compared with NSTEMI (20.6%) and 88.9% were non-reperfused infarctions. 65.9% of patients were male and 57.1% had hypertension. In-hospital mortality was present in 40 patients (31.7%). Ischemia of the papillary muscle was the most commonly reported mechanism (38.1%), followed by alterations in the left ventricle's geometry (33.3%), mitral annular dilation (14.3%), papillary muscle rupture (7.1%) and chordae tendineae rupture (5.6%). The least frequently reported mechanism was pre existing non-ischemic mitral regurgitation (1.6%). There was no significant difference in mortality based on the mechanism responsible for aiMR. Patients with aiMR managed solely with medical therapy had a higher mortality rate (41.3%) compared to those undergoing mitral valve replacement (37%) (Figure 1). Timely reperfusion (thrombolysis/primary PCI) significantly reduced in-hospital mortality (85% survival) in contrast to those with a non-reperfused MI (66% survival). Conclusions Acute ischemic mitral regurgitation remains an entity with a high mortality rate. Early identification of underlying etiology, prompt reperfusion treatment and tailored surgery, if needed, are key to improve outcomes.