Study The Value Of Corrected QT Interval For Clinical Significance Of Non-ST-segment Elevation Myocardial Infarction Patients

Objective:To analysis the clinical characteristics of corrected QT interval in patients with on-ST-segment elevation myocardial infarction.To study the value of corrected QT interval for early diagnosis,the lesion features of coronary artery,infarction related artery and short-term prediction prognosis of non-ST-segment elevation myocardial infarction patients.Methods : A tota1 of 168 patients with who were suspected of non-ST-segment elevation myocardial infarction from Jan.2013 to Oct.2015 in Department of Cardiology,The First Affiliated Hospital of Wannan Medical College and Chizhou People's Hospital were studied,a standard 12-lead ECG was recorded.All patients were coronary angiography(CAG)examination.126 patients were diagnosed as NSTEMI.The QT interval was measured manually and the corrected QT interval was deduced using Framingham formula.The 126 patients with NSTEMI were divided into two groups:prolonged QTc interval group(QTc was?450ms in men and ?470ms in women)and normal QTc interval group.Ths clinical characteristics of prolonged QTc interval group and normal QTc interval group were analyzed.NSTEMI was diagnosed when QTc was?450ms in men and ?470ms in women.To assess the sensitivity and specificity of prolonged QTc interval in diagnosis of NSTEMI.The lesion characteristics of coronary artery and IRA were studied.The patients with NSTEMI were followed up for 3 months after discharge to observe the major adverse cardiovascular events.Results:(1)126 patients diagnosed as NSTEMI,patients with prolonged QTc interval group were older,heart beat faster and higher level of CK-MB and c TNI compared with patients with normal QTc interval group,more likely to be with heart function killip grades ?-?(P<0.05).(2)Predict NSTEMI was diagnosed when QTc was?450ms in men and ?470ms in women,the sensitivity was 67.5%,the specificity was 59.5%.Prolonged QTc interval were significantly higher in NSTEMI group than non NSTEMI group(P<0.01).(3)There were significantly more three vascular lesions disease and left main coronary artery+three vascular lesions disease in prolonged QTc interval group than normal QTc interval group(P<0.01).Totally occluded lesion disease were more likely to be seen in prolonged QTc interval group(P<0.05).There were less zero vascular lesions and mild stenosis disease in prolonged QTc interval group than normal QTc interval group(P<0.05).There exist no significant differences in IRA compared prolonged QTc interval group and normal QTc interval group.The IRA was often 1eft circumflex coronary artery in normal QTc interval group.(4)There were 22 patients with NSTEMI suffered from major adverse cardiovascular events during the follow up period of time.There were more major adverse cardiovascular events in prolonged QTc interval group than normal QTc interval group(P<0.05).Conclusions:QTc can only be used for the auxiliary diagnosis of NSTEMI.There are differences between prolonged QTc interval and normal QTc interval groups in clinical characteristics,the lesion features of coronary artery and prognosis.Patients in prolonged QTc interval group were older,heart beat faster and higher level of CK-MB and c Tn I,and more likely to be with heart function killip grades ?-?.The severe and extensive coronary arteries lesions were observed in prolonged QTc interval group.The morbidity of left main coronary artery and three vascular lesions disease was higher in prolonged QTc interval group than normal QTc interval group.The prognosis is worse in prolonged QTc interval group with NSTEMI.Prolonged QTc interval might be a predict risk factor of major adverse cardiovascular events in patients with NSTEMI.