孤立性心肌致密化不全患者左心室收缩功能相关MRI研究

Analysis of left ventricular systolic function in patients with isolated ventricular noncompaction by cardiac MRI

目的比较左心室收缩功能正常与减低孤立性心肌致密化不全（IVNC）患者MRI的差别，分析与IVNC左心室收缩功能相关的因素。方法回顾性搜集62例IVNC患者和30名健康志愿者（对照组），IVNC患者按左心室射血分数（LVEF）分为LVEF正常（20例，LVEF≥55％）和减低（42例，LVEF〈55％）2组，所有受试者均进行心脏MRI扫描，并计算LVEF、左心室体积、致密化不全节段数、非致密化心肌与致密化心肌厚度比值（NC／C）以及延迟强化的比例，采用单因素方差分析、t检验和χ^2检验进行比较。最后对IVNC患者LVEF值与致密化不全节段数、NC／C比值的相关性分别进行Spearman和Pearson分析。结果LVEF正常组和减低组LVEF值分别为（58．8±3．8）％、（31.1±11．1）％，均低于对照组[（66．1±6．0）％]，并且3组间两两比较差异均有统计学意义（F=140．789，P〈0.01）。IVNC患者收缩末期及舒张末期左心室体积及左心室体积指数均较对照组增大，但LVEF正常组与对照组之间差异无统计学意义（P值均〉0．05），而LVEF减低组患者左心室体积增大更明显，与LVEF正常组患者及对照组差异有统计学意义（P值均〈0．05）。LVEF减低组患者致密化不全节段数（7．5±1．0）多于LVEF正常组（5．6±1．0），NC／C比值（4．4±0．9）大于LVEF正常组（3．4±0．7），差异有统计学意义（t值分别为7．248、4．472，P值均〈0．01）；LVEF减低组患者心肌延迟强化比例（18／42）高于LVEF正常组（1／20），差异有统计学意义（χ^2=9．136，P〈0．01）。所有IVNC患者LVEF值与致密化不全节段数及NC／C比值呈负相关（r值分别为-0．690、-0．59l，P值均〈0．01）。致密化不全节段分布上两组患者心尖段、心尖部及中部侧壁为最常见的受累部位，基底部间隔壁、中部间隔壁及中部下壁均未见受累。但LVEF减低组部分患者可见基底部节段受累，而LVEF正常组未见基底部受累。结论IVNC患者左心室体积增大、重构和心肌延迟强化都会导致左心室收缩功能下降，而且其左心室收缩功能与非致密化心肌范围和程度呈负相关。

Objective To compare cardiac magnetic resonance imaging （MRI） features between patients with normal and decreased left ventricular （LV） systolic function in isolated ventricular noncompaetion （IVNC） and to analyze the related factors of LV systolic function. Methods In a retrospective blinded study, 62 IVNC patients were divided into two subgroups： those with normal LV systolic function [LV ejection fraction （LVEF）≥55%）] and those with decreased LV systolic function （LVEF〈 55%）. A total of 30 healthy volunteers were enrolled as controls. The LVEF, LV volume, number of non-compacted segments, ratio of non-compacted to compacted myocardium （NC/C ratio）, and delayed enhancement were assessed using cardiac MRI. One-way analysis of variance, independent t test and Z2 test were used. The correlation between LVEF and the number of non-compacted segments or NC/C ratio were calculated with Spearman and Pearson correlation analysis. Results The LVEF of patients with normal LVEF [（58.8±3.8）%] and patients with decreased LVEF [（31.1±11.1）%] were less than that of control group [（66.1±6.0）%], which demonstrated significant differences （F=140.789, P〈0.01）. The patients with decreased LVEF had greater LV end-diastolic volume （EDV） and end-systolic volume （ESV） compared with patients with normal LVEF and the control group, both before and after adjustment for body surface area. However, there were no significant differences of the LV volume between patients with normal LVEF and control group （P〉0.05）. The patients with decreased LVEF had significantly greater LV volume compared with patients with normal LVEF and control group （P〈0.05）. The number of non-compacted segments in patients with decreased LVEF （7.5±1.0） was more than that of the patients with normal LVEF （5.6±1.0）, and the NC/C ratio in patients with decreased LVEF （4.4±0.9） was higher than that of patients with normal LVEF （3.4±0.7）, which demonstrated significant differences （t=7.248,4.472, P〈0.01）. There was significant difference in the rate of delayed enhancement between patients with decreased LVEF （18/42） and patients with normal LVEF （1/20） （χ^2=9.136, P〈0.01）. The non-compacted segments were more common in apex, apical and mid lateral segments in two IVNC groups, and there were no involvement of basal septal, mid septal and mid inferior segments. Some basal segments were involved in patients with decreased LVEF, while there were no basal segments involved in patients with normal LVEF. The number of non-compacted segments and NC/C ratio were correlated negatively with LVEF （r=- 0.690,- 0.591, respectively, P〈0.01）. Conclusions The dilation, remodeling and myocardial delayed enhancement of LV in IVNC patients can lead to decreased LV systolic function. In addition, the extent and severity of non-compacted myocardium in IVNC patients are correlated negatively with LVEF.