MI後の僧帽弁修復による有益性はほとんどまたは全くない（Abstract 20772）

虚血性僧帽弁逆流症患者においてCABGに加え僧帽弁修復を施行することによる利益はない
No gain seen to adding mitral valve repair to CABG in patients with ischemic mitral regurgitation
心筋梗塞後の中等度の僧帽弁傷害患者において冠動脈バイパス術（CABG）後にルーチンに僧帽弁修復術を追加することは是認されない可能性がある、とのスタディ結果が2014年American Heart Association年次集会で発表され、同時にNew England Journal of Medicineに掲載された。このスタディは中等度の虚血性僧帽弁逆流（MR）に対し片方または両方の手術を施行された患者301人を対象とした。研究者らは、心収縮後の左室内残存血液量を6か月後および12か月後に計測することにより各々の患者の状態を評価した。両方の手術を受けた患者とCABG単独治療を施行された患者とで1年後の左心室の器質的障害からの回復、および心不全、脳卒中、機能的状態またはQOLなどの二次計測値には差が認められなかった。しかし、僧帽弁修復術の追加は神経学的イベント増加、クロスクランプや心肺バイパス時間増加、およびICU在室時間や入院期間が長いことと関連があった。さらに長期の追跡調査が現在行われている。
Full Text

Routinely adding mitral valve repair to coronary artery bypass graft surgery for myocardial infarction (MI) patients may not be warranted in patients with moderate mitral valve damage, according to an NIH-funded study. Patients treated with both procedures versus the bypass graft alone showed no differences at one year in recovery from structural damage to the heart's left ventricle, nor in secondary measures such as heart failure, stroke, functional status or quality of life. 

The results of the Surgical Interventions for Moderate Ischemic Mitral Regurgitation (IMR) study, supported by NIH's National Heart, Lung, and Blood Institute (NHLBI), were presented at the American Heart Association Scientific Sessions in Chicago and published simultaneously in the New England Journal of Medicine.

Of patient suffering a myocardial infarction, about half are left with functional damage to the mitral valve due to the injury and changes to the heart muscle. This damage can result ischemic mitral regurgitation.

Doctors typically treat MI patients with this condition by performing coronary artery bypass graft surgery, sometimes adding mitral valve repair to fix the leaky mitral valve. The study is the first large-scale randomized clinical trial to assess whether adding the repair procedure leads to a measurable benefit for patients.

The study included 301 patients with moderate IMR who had been treated with one or both surgical procedures. Researchers assessed each patient's condition at six and 12 months by measuring the amount of blood remaining in the left ventricle after a heart contraction. Both patient groups showed similar rates of improvement at the 12-month assessment.  

At 1 year, when compared with CABG alone, the addition of mitral valve repair to CABG did not result in a greater degree of left ventricular reverse remodeling or an improvement in mortality, MACE, hospital readmission or quality of life.  However the addition of MV repair was associated with more neurologic events, increased cross clamp and cardiopulmonary bypass times, and longer ICU and hospital lengths of stay.  Longer-term follow-up is ongoing.

This research was conducted as part of NHLBI's Cardiothoracic Surgical Trials Network and was co-funded by the National Institute for Neurological Diseases and Stroke and the Canadian Institutes for Health Research.