The Study Of Correlation Between Left Ventricular Diastolic Dysfunction And QT Interval In Idiopathic Inflammatory Myopathy

Background:Idiopathic inflammatory myositis(IIM),including the most common clinical type of polymyositis(PM) and dermatomyositis(DM),is a group of non-suppurative inflammation of skeletal muscle myopathy characterized by proximal muscle weakness. Cardiac damage is the common complication of adult IIM, which is one of the most important causes of death.So, the echocardiography(UCG) and electrocardiogram(ECG)play an important role on early diagnosis and prognosis of cardiac involvement in IIM patients. UCG can accurately assess myocardial diastolic dysfunction, and left ventricular diastolic dysfunction is the most common echocardiographic manifestations in IIM.ECG is very convenient and fast to get as a general routine examination,however, the study about the evaluation of ECG on left ventricular diastolic function in IIM patients is rare. Therefore, We mainly collected ECG and UCG parameters and focused on the analysis of relationship between left ventricular diastolic dysfunction and QT interval. Objective:To Study the correlation between left ventricular diastolic dysfunction and QT interval in idiopathic inflammatory myopathy. Methods:We accepted the adult inpatients diagnosed with PM or DM in Chengdu NO.3 People Hospital, Hainan Provincial People's Hospital and West China Hospital of Sichuan University.325 PM/DM patients were surveyed and we brought into 56 patients( male 15, female 41, PM 19, DM 37) who reached the standard and data integrity finally. 56 age- and sex-matched healthy controls with UCG and ECG were included at the same time. We collected their general information, clinical data, laboratory tests, electrocardiogram and echocardiography parameters. The parameters of ECG and UCG between patients with idiopathic inflammatory myopathy and controls were displayed, the Pearson correlation analysis and multiple linear regression analysis showed the correlation between corrected QT interval(QTc) and early diastolic myocardial velocity(E?). What's more, the ROC curve was used to evaluate the QTc diagnostic value of left ventricular diastolic dysfunction. Results:1.In PM/DM patients, interstitial lung disease, dysphagia, myalgia, arthralgia, rash, Raynaud's phenomenon, E/A<1 and E?<8cm/s respectively accounted for 25%(14/56),21.4%(12/56),55.4%(31/56),44.6%(25/56),60.7%(34/56),8.9%(5/56),48.2%(27/56),58.9%(33/56).2.The levels of RBC,HB, T-Bil, Cr,and HDL-C in PM/DM were significantly lower than in controls.The TG was higher(P<0.05). In the parameters of ECG,the levels of QTc and HR in PM/DM were significantly higher than in controls(447.1±24.9 vs 420.9±22.6,87±15.7vs68±9.9 P<0.05). The levels of QT, QTmax and QTmin were significantly lower(375.3±32vs394.8±24,385.7±32.8vs399.3±28.5,339±35.8vs358.3±31.3 P<0.05).But the levels of PR and QTd showed no significant difference between the two groups. In the parameters of UCG, the level of A in PM/DM was higher than in controls(0.78±0.23vs0.68±0.13, P<0.05),the level of E/A was significantly lower(1.05±0.42 vs 1.23±0.31,P<0.05), and cases in PM/DM of left ventricular diastolic dysfunction were more than that of controls( 48.2% vs 21.4%,P < 0.05).But the levels of LV,LA,RV,E,EF,FS,and IVS showed no significant difference between the two groups.3.The correlation between E?and QTc: Comparing the different grades of left ventricular diastolic function,we found that the worse the left ventricular diastolic function was, the longer the QTc showed. QTc level correlated negatively with E?(r=-0.411,P=0.002). After adjustment for gender and disease duration, multiple linear regression analysis demonstrated that age and QTc were closely related with left ventricular diastolic dysfunction B=-0.362(P=0.003).4.The evaluation of QTc to left ventricular diastolic dysfunction in patients with PM/DM:The area under a receiver-operating characteristic(ROC) curve of QTc was 0.791 for left ventricular diastolic dysfunction(95% CI 0.728~0.908,P?0. 05),and with the optimal cut-off value of 443.5ms, QTc showed a diagnostic sensitivity of 0.727 and specificity of 0.783. 5. The results grouped by E/A and E/E on the left ventricular diastolic function:In the E/A group,the age was positively correlated with left ventricular diastolic dysfunction(P=0.003). In the E/E? group, the long disease duration(B=0.041,P=0.037) and prolonged QTc(B=0.046,P=0.048)were positively correlated with left ventricular diastolic dysfunction. Conclusions:1. Idiopathic inflammatory myopathy patients are often accompanied by abnormal left ventricular diastolic function and QT interval.2. Prolonged QTc is a related index with left ventricular diastolic dysfunction in patients with idiopathic inflammatory myopathy, and the idiopathic inflammatory myopathy patients are more likely to be concomitant with left ventricular diastolic dysfunction when the cut-off of QTc is 443.5ms.3.We suggest the idiopathic inflammatory myopathy patients should receive conventional electrocardiogram and echocardiography.