心脏磁共振成像对急性病毒性心肌炎患者左心室功能改善的预测价值

Predictive value of cardiac magnetic resonance-derived parameters on the improvement of left ventricular function in patients with acute viral myocarditis

目的 探讨心脏磁共振成像对急性病毒性心肌炎患者左心功能改善的预测价值.方法 前瞻性纳入2011年9月至2015年9月在南方医科大学顺德医院诊断为急性病毒性心肌炎的患者40例.入选患者在临床急性期（首次）及1年后均行心脏磁共振成像检查,扫描序列包括常规二维稳态自由进动、左心室短轴面三反转恢复序列T2WI、注射对比剂前后左心室短轴T1WI扫描、三维相位敏感反转恢复超快速场回波序列,收集数据并进行统计学分析.结果 首次心脏磁共振成像检查发现40例急性病毒性心肌炎患者中30例符合心肌炎路易斯湖标准,10例不符合.符合路易斯湖标准的患者首次及1年后复查的左心室射血分数（LVEF）均低于不符合路易斯湖标准的患者（P＜0.01或0.05）,首次左心室收缩末期容积指数（LVESVI）高于不符合路易斯湖标准的患者（P＜0.05）.1年后LVESVI以及首次和1年后左心室舒张末期容积指数（LVEDVI）两组间差异均无统计学意义.首次及1年后复查LVEF、LVESVI、LVEDVI组内比较结果显示符合路易斯湖标准的患者1年后复查LVEF显著增加（P＜0.05）,而不符合路易斯湖标准的患者1年后复查LVEF未见明显变化（P＞0.05）.而无论是否符合路易斯湖标准1年后复查,患者LVESVI和LVEDVI均未见明显变化（P均＞0.05）.组内比较结果显示符合路易斯湖标准、水肿比（ER）阳性、全心肌相对增强（gRE）阳性的患者1年后复查LVEF显著增加（P均＜0.05）,而不符合路易斯湖标准、ER阴性、gRE阴性、延迟强化（LGE）阴性、LGE阳性的患者1年后复查LVEF未见明显变化（P均＞0.05）.进一步将入选患者分为心功能改善组（ALVEF≥5％）和无改善组（ALVEF ＜5％）,采用卡方检验统计分析结果发现路易斯湖标准、心肌水肿与心功能改善有关（P均＜0.05）,而gRE、LGE与心功能改善未见明显关联（P均＞0.05）.以路易斯湖标准中的各项诊断指标（ER、gRE和LGE）为自变量,LVEF变化为因变量,运用多元线性回归分析探讨二者的关系,发现ER阳性是急性病毒性心肌炎患者LVEF改善的最强独立预测因子（完全模型：非标准系数0.445,P=0.043;简化模型：非标准系数0.442,P=0.12）.结论 心脏磁共振成像可较好地预测急性病毒性心肌炎患者左心功能的改善情况,其中心肌水肿成像阳性的预测价值最大.

Objective To evaluate the predictive value of cardiac magnetic resonance （CMR）-derived parameters on the improvement of left ventricular function in patients with acute viral myocarditis.Methods Forty patients,who referred for acute viral myocarditis in our hospital from September 2011 to September 2015,were prospectively enrolled in this study.All patients were examined by CMR during hospitalization for acute viral myocarditis （baseline） and after 12 months.The CMR sequences include：two dimension steady state free precession,2D SSFP;triple inversion recovery,triple IR;early gadolinium enhancement;phase sensitive inversion recovery turbo field echo,PSIR TFE.Results Thirty out of 40 patients with susceptive acute viral myocarditis met the CMR criteria of acute viral myocarditis （Lake Louise Criteria） （LL ＋） and the other 10 patients did not meet the diagnostic criteria （LL-）.Left ventricular ejection fraction （LVEF） values were significantly lower in LL ＋ group than in LL-group at baseline and at 12 months after discharge （P ＜ 0.01 or 0.05,respectively）.The baseline left ventricular end-systolic volume index （LVESVI） was significantly higher in LL ＋ group than in LL-group （P ＜ 0.05） and was similar between the groups at 12 months follow up.Left ventricular end-diastolic volume index （LVEDVI） was similar between the two groups at baseline and at 12 months follow up.LVEF was significantly higher during 12 months follow up compared to baseline in LL ＋ group and remained unchanged in LL-group during the two time points.LVESVI and LVEDVI remained unchanged at baseline and during 12 months follow up both in LL ＋ and LL-groups （P ＞ 0.05）.Results showed that LL ＋,edema ratio （ER） positive and global relative enhancement （gRE） positive were associated with significant increase of LVEF at 12 months follow up.However,LL-,ER negative,gRE negative,late gadolinium enhancement （LGE） negative and LGE positive linked with unchanged LVEF at 12 months follow up （P ＞ 0.05）.Patients were further divided into LVEF increase （ALVEF≥5％） group and non LVEF increase group （ALVEF ＜5％）,the results of Chi-square test showed that LL ＋ and ER positive were related to the improvement of LVEF （P ＜ 0.05）,while gRE and LGE were not associated with improvement of cardiac function （P ＞0.05）.Multiple linear regression analysis,using ER,gRE and LGE as independent variables and LVEF as dependent variables,showed that the presence of myocardial edema was the strongest independent predictor of an increase in LVEF at follow up （full model：non-standardized coefficient 0.445,P =0.043;reduced model：non-standardized coefficient 0.442,P =0.12）.Conclusion Cardiac magnetic resonance imaging monitoring is valuable to observe the cardiac function and morphology changes in patients with acute viral myocarditis,and myocardial edema imaging is the most powerful parameter to predict the improvement of LVEF in this patient cohort.