The Forecast Effect Of QT Dispersion On Prognosis Of Percutaneous Coronary Intervention

ObjectiveQT dispersion (QTd) means the dispersion of each lead of 12-lead ECG. It indicatesthe inhomogeneity of ventricular muscle repolarization and the inconsistency degreeof ventricular muscle excited recovery time. The inspection of QTd is noninvasive,simple and economy. As a prediction indicator of sudden coronary death andventricular arrhythmia, QTd has been a hotspot of research in recent years. Manyclinical reports describe that QTd has the important reference value of evaluatingearly reperfusion efficacy, myocardial infarction area, the complications andprognosis of acute myocardial infarction (AMI) patients. Besides these, QTd also hasa certain value of the assessment of antiarrhythmic drug efficacy and forecast ofarrhythmias caused by antiarrhythmic drugs. Based on the mensuration of QTd andthe clinical follow-up of the patients by successful percutaneous coronaryintervention (PCI), we not only analyzed the QTd changes of coronary heart diseasepatients after PCI, but also evaluated the effect of PCI on QTd and discussed theforecast effect of QTd on PCI prognosis.Method1067 patients who were treated by PCI from January 2000 to January 2007 wereselected consecutively as the research group and another 213 patients with negativecoronary angiography inspection result were selected as the control group. Theresearch patients were then divided into AMI group (457 cases) and unstable anginapectoris(UA) group (610 cases) according to clinical symptoms, electrocardiographyand myocardial enzyme results. Among the AMI group, 277 patients were treated with primary PCI, 53 patients with rescue PCI and 127 patients with elective PCI. Allthese patients were followed up by telephone, letters, outpatient review or re-patienthospitalization. Follow-up patients were divided into survival group, acute coronarysyndrome (ACS) readmission group and sudden cardiac death group. All patients'QTd were assayed before and after PCI. The values of QTd were obtained with12-lead ECG and the calculating result (QTd=QTmax-QTmin). The QTd relationbetween different groups was tested with SPSS 13.0 software and the statisticallysignificant exists if P＜0.05.Results①The QTd of research group was higher than control group no matter pre-operationor post-operation. The QTd of research group significantly reduced after PCI but theQTd of control group didn't change after coronary angiography inspection.②The QTd of UA group and AMI group reduced after PCI respectively, especiallythe UA group. The QTd of AMI group was higher than UA group no matterpre-operation or post-operation.③Comparing QTd of PCI in 6 hours, 6-12 hours and 7-10 days patients in AMIgroup we discovered that QTd of the＜6h group were significant less than the othertwo groups no matter pre-operation or post-operation and there is no differencebetween the 6-12h group and the 7-10d group before PCI, but after PCI, the 6-12hgroup were less than the 7-10d group. The QTd reduced after PCI in all of the threegroups respectively.④In the AMI group and UA group respectively, the QTd of different stenosesposition have no significantly difference and the QTd of three vessel disease groupwere longer than double vessel disease group which were even longer than singevessel group.⑤Whether AMI group or UA group, in the follow-up of asymptomatic survival group, ACS readmission Group and sudden cardiac death group, the QTd reduced after PCIrespectively and the decrease in Sudden cardiac death group was significant less thananother two groups but no statistically significant difference between theasymptomatic survival group and ACS readmission Group.Conclusion①QTd are increased in both AMI and UA patients. Successful PCI can shorten theQTd of these patients, improve cardiac electrical stability, and then reduce theincidence of malignant arrhythmia.②Both AMI patients and UA patients can benefit from PCI, particularly the UApatients.③Successful PCI may notably reduce QTd of AMI patients, whose earlierperformance usually produces better effects.④QTd can help to reflect the range of coronary artery stenosis and the locationhardly influenced OTd no matter AMI patients or UA patients.⑤The decrease of QTd can forecast the long-term clinical prognosis of patients withPCI. The patients with little decrease have a high risk of sudden cardiac death.Innovations①In this work the quantity of samples are huge and the results are reliability. Westudied the QTd of 1,067 cases with PCI both preoperative and postoperative. Similarresearch has not been reported.②Since 994 patients were followed up in our research we found that QTd isconsiderably valuable for evaluating the long-term prognosis after PCI and the QTddecrease can be the forecast indicators of long-term prognosis of PCI.③It was confirmed from the point of view of the QTd decreased degree on prognosisthat the AMI patients should be treated with PCI as soon as possible.