Value Of Electrocardiogram Techniques In Sudden Death Risk Assessment For Patients With Dilated Cardiomyopath

Objective: Dilated Cardiomyopathy(DCM) is a common disease withhigh mortality and poor prognosis. The patients with DCM mostly die ofintractable heart failure and lethal ventricular tachyarrythmia. The patients'5-year-survival rate is approximately50%, and these deaths approximately50%are due to sudden and unexpected cardiac death (SCD). DCM is associatedwith a high rate of SCD, especially in young, which are producing severeproblems to family and society. It is urgent to find ideal risk factors forprediction and prevention of sudden death in DCM.At present, there are many studies about the risk factors of SCD, but withpoor sensitivity and specificity, and which risk factors are more effective areunclear. Recently, data from the Framingham study showed that theappearance of left ventricular hypertrophy on ECG increases the age-adjustedrisk of all cardiovascular events4-to7fold, and the risk of sudden death3-to5-fold. It has been reported that increased ECG-voltage amplitude is asignificant risk factor of hypertrophic cardiomyopathy for sudden death. Inthat study the QRS-amplitude sum in limb-leads for both sexes was found abetter predictor than Sokolow-Lyon index, with strongly sensitivity andspecificity, while limb-lead amplitude-duration product and12-lead amplitude–duration product are more better than the QRS-amplitude sum in limb-leads,with limb-lead amplitude-duration product≥0.7mvs (odds ratio31.5, p <0.0001) and12-lead amplitude-duration product≥2.2mvs (odds ratio31.0, p<0.0001). Until now, the ECG-amplitudes sum and ECG-amplitude-durationproduct as predictors of sudden death in patients with DCM have not beenstudy.The aim of this study is to determine whether or not the QRS-amplitudesum in limb-lead, ECG-amplitude-duration product of limb-lead or12-leadand other characters of electrocardiogram could be risk factors of DCM for identifying SCD.Methods:65patients with dilated cardiomyopathy were divided into twogroups, dilated cardiomyopathy with cardiac arrest and dilatedcardiomyopathy cohort, according to history of SCD.56healthy adult wereregularly medical examination in our hospital as normal cohort. We collectdata of ECG of dilated cardiomyopathy with cardiac arrest before the adventof SCD, if not, collecting data of ECG from the first date of admission.However in dilated cardiomyopathy cohort and normal cohort, we choose dataof12-lead electrocardiogram or24-hour ambulatory electrocardiographicmonitoring from the first date of admission. According to data of ECG, theQRS-amplitude sum, and ECG-amplitude-duration product in limb-leads and12-lead were analyzed. The differences of ECG-amplitudes of patients withdilated cardiomyopathy between cardiac arrest and cohort were made out.Whether or not ECG-amplitudes could be consider as predictors of dilatedcardiomyopathy for SCD were picked out.Results:1. The incidence of low voltage of limb-lead amplitude and increasedvoltage of left ventricle is low in dilated cardiomyopathy, and the sensitivityfor predicting sudden death were:22.7%,13.6%, respectively. Thus, they areinadvisable predictors for identifying patients with high risk for sudden death.2. When the QRS-amplitude sum in limb-leads value for both sexesbetween3.0mv and7.0mv, the relatively high sensitivity is63.6%(OR=0.68,95%CI0.23～2.03; p=0.485), with instable odds risk due to includingineffective1.0. In addition, p>0.05demonstrates that the usefulness of theQRS-amplitude sum in limb-leads for SCD risk prediction is limited by thelarge overlap of the QRS-amplitude sum in limb-leads between patients withand without SCD events. Therefore, it dose not help to identify patients whoare at risk for sudden death.3. Similarly to the QRS-amplitude sum in limb-leads, the Sokolow-Lyonindex≥2.0mv,limb-lead amplitude-duration product≥0.37mvs and12-leadamplitude–duration product≥1.37mvs, with relatively high sensitivity and specificity, have not been helpful in predicting the DCM patients at high riskfor SCD.4. When the limb-lead amplitudes sum≥7.7mv, limb-leadamplitude-duration product≥0.7mvs,12-lead amplitude-duration product≥2.2mvs and Sokolow-Lyon index≥3.8mv, are also without helpful inpredicting the DCM with increased risk for SCD due to low sensitivity,respectively:13.6%,18.2%,36.4%and13.6%.5. Our study also shows that the ECG-amplitudes sum in six chest leadsand twelve leads have the similar result, with little value of predictors forSCD.6. Logistic regression analysis shows that QT dispersion (QTd),frequently multifocal premature ventricular contraction (MPVC) and leftventricular ejection fraction (LVEF) are strongly associated with SCD.Patients with dilated cardiomyopathy with QTd≥60ms increased the risk ofSCD6.89fold than QTd <60ms, DCM with frequently MPVC (odds ratio10.09, p<0.001). There is a negative correlation between LVEF and SCD(odds ratio0.24, p<0.001), with increasing deteriorated function of leftventricle, the risk of SCD is more high.Conclusion: ECG-amplitude sums, ECG-amplitude-duration productsand Sokolow-Lyon index are little association with SCD of dilatedcardiomyopathy, which are inability risk predictors of dilated cardiomyopathyfor SCD. But left ventricular ejection fraction, frequently multifocalpremature ventricular contraction and QT dispersion are strongly related withSCD of DCM. The worse patients' heart function with DCM get and the morefrequently MPVC and increased QT dispersion the patients have, the moresevere risk of SCD is.