心脏MR对心肌梗死合并慢性二尖瓣反流的评估价值

Value of cardiac MR in evaluating myocardial infarction with chronic mitral insufficiency

目的 探讨心脏磁共振(CMR)对冠心病心肌梗死患者合并慢性缺血性二尖瓣反流(IMR)评估的价值.方法 回顾性选择2016年1月至2018年9月在本院经临床确诊为冠心病心肌梗死患者共130例,心梗时间≥3个月,并接受CMR检查证实存在坏死心肌,所有患者均于同期行超声心动图检查.基于超声心动图结果,将患者分为心肌梗死未合并IMR组(40例)、合并轻度IMR组(39例)和中重度IMR组(51例).分析CMR电影及延迟增强(LGE)扫描图像,测量心功能指标并记录左心室LGE阳性节段.采用特征追踪技术(FT)测量不同程度IMR患者左心室整体心肌纵向应变(GLS)、圆周应变(GCS)及径向应变(GRS)指标.无IMR、轻度IMR及中重度IMR组的心血管相关病史、冠状动脉造影结果及心梗发生位置等计数资料比较采用χ2检验;左心室心肌梗死体积(IS)、左心功能及左心室心肌整体应变各项指标等计量资料比较采用单因素方差分析,进一步两两比较采用LSD检验.结果 3组患者年龄、性别及心血管相关病史差异无统计学意义.三组心肌梗死患者比较:(1)3组患者心肌梗死体积总体差异无统计学意义(P=0.052),而随着二尖瓣反流分级程度增高,心肌梗死体积有增大趋势.中重度组IMR下壁及下侧壁心肌梗死的患者数量明显高于其他两组(P<0.05),未合并IMR与轻度IMR两组间心肌梗死体积差异无统计学意义,下壁及下侧壁心肌梗死的患者数量差异无统计学意义.(2)CMR测量心功能结果:中重度IMR组与未合并IMR组、轻度IMR组比较,射血分数(EF)明显减低(P<0.05),舒张末期容积(EDV)及收缩末期容积(ESV)明显增大(P<0.05),心肌质量(LVM)明显增加(P<0.05),而每搏输出量(SV)及心输出量(CO)比较差异无统计学意义.(3)中重度IMR组分别与未合并IMR组及轻度IMR组比较:左心室GLS及GRS值减低(P<0.05),GCS值差异无统计学意义.而未合并IMR组与轻度IMR组比较3种应变值差异均无统计学意义.结论 心肌梗死合并慢性中重度IMR患者左心室心肌应变受损明显,左心室乳头肌水平下壁、下侧壁心肌梗死可能与慢性中重度IMR相关,左心室心肌梗死体积亦有可能与其有关.

Objective To evaluate the value of cardiac MR imaging in chronic ischemie mitral regurgitation(IMR)in patients with myocardial infarction.Methods All patients clinically diagnosed with coronary heart disease and myocardial infarction in our hospital from January 2016 to September 2018 were retrospectively selected,myocardial infarction time more than 3 months and confirmed to have necrotic myocardium by cardiac magnetic resonance examination.All patients underwent echocardiography at the same time.Based on the results of echocardiography,patients were divided into the myocardial infarction group without IMR(40 cases),the mild IMR group(39 cases)and the moderate to severe IMR group(51 cases).Cardiac MR and delayed enhancement(LGE)scan images were analyzed.Cardiac function indexes were measured and left ventricular LGE positive segments were recorded.The indexes of myocardial global longitudinal strain(GLS),global peripheral strain(GCS)and global radial strain(GRS)of left ventricle of IMR patients were measured by feature tracking(FT).Cardiovascular history,coronary artery stenosis and location of myocardial infarction were compared by chi-square test between the without IMR,mild IMR and moderate to severe IMR groups.Univariate analysis of variance was used to compare the measurement data of left ventricular myocardial infarction volume,left heart function and left ventricular myocardial globle strain,and LSD test was used for pair-wise comparison.Results There was no difference in age,sex and cardiovascular history among the three groups.Comparison of myocardial infarction patients in the three groups:(1)There was no statistically significant difference in the myocardial infarction volume between the three groups(P=0.052),while the myocardial infarction volume tended to increase as the grade of mitral regurgitation increased.The number of patients with myocardial infarction in the inferior wall and the inferolateral wall in the moderate to severe IMR group were significantly higher than those of the other two groups(P<0.05),and there was no significant difference in the volume of myocardial infarction between the without IMR group and mild IMR group,and no difference in the number of patients with inferior wall and inferolateral wall.(2)Cardiac function measured by CMR:ejection fraction(EF)was significantly reduced in the moderate to severe IMR group compared with the without IMR group and the mild IMR group(P<0.05),the end diastolic volume(EDV)increased significantly and the end systolic volume(ESV)increased significantly(P<0.05).Mass of myocardium increased significantly(P<0.05);Stroke volume(SV)and cardiac output(CO)there was no significant difference among the three groups.(3)Comparison of the moderate to severe IMR group to the without IMR group and the mild IMR group respectively:left ventricular GLS and GRS decreased(P<0.05),the difference of the GCS was no statistically significant.There was no statistical difference in the three strain values between the without IMR group and the mild IMR group.Conclusion The globe myocardial strain of the left ventricle in myocardial infarction patients with chronic moderate to severe IMR was significantly impaired,the myocardial infarction in the inferior wall and the inferolateral wall in the level of the papillary muscle may be correlated with chronic moderate to severe IMR,and the myocardial infarction volume of the left ventricle may also be related.