Objective To investigate the clinical significance of ECG QRS wave extension of the time limit for heart failure patients.Methods A retrospective analysis of heart failure patients electrocardiogram QRS complex duration and ultrasound heartbeat graph parameters were conducted,and according to the ECG QRS complex duration the patients were divided into QRS ≥ 120ms group and Q RS ＜ 120ms group,The cardiac functional grading,ultrasound heartbeat graph parameters,incidence rate of malignant arrhythmia,mortality within 1 year were compared between the two groups,in order to explore the possibility of QRS complex duration and the United States of America New York Heart Association(NYHA) classification of cardiac function,left ventricular end diastolic diameter(LVEDd),left ventricular ejection fraction(LVEF),left ventricular fraction shortening(LVFS),malignant arrhythmia incidence,mortality.Results No significant difference was found in the cardiac function between QRS ≥ 120ms group and QRS ＜120ms group(t =0.00,0.10,0.11,all P ＞ 0.05).LVEDd of ECG QRS complex duration ≥ 120ms group was significantly higher than that of ECG QRS complex duration ＜ 120ms group (t =3.31,P ＜ 0.05).In addition,LVFS value and LVEF value of ECG QRS complex duration≥ 120ms group were significantly lower than those of ECG QRS complex duration ＜ 120ms group (t =17.05,3.54,all P ＜0.05).However,LAD between the two groups had no significant difference(t =0.09,P ＞ 0.05).40 cases in ECG QRS complex duration ≥ 120ms group,8 cases had malignant arrhythmia in the hospital,6 cases of cardiac death,2 patients died of pulmonary infection.In ECG QRS complex duration ＜ 120ms group,4 cases had malignant arrhythmia during hospitalization,3 cases of cardiac death,1 cases died of septic shock.The incidence rate of malignant arrhythmia and mortality within 1 year of ECG QRS complex duration ≥120ms group were significantly higher than those of ECG QRS complex duration ＜ 120ms group (x2 =4.01,P ＜0.05).In the ECG QRS complex duration ≥ 120ms group,LVEDd of 6 cardiac death patients was higher than 70mm,LVEF was less than 30％.Conclusion Wave duration ≥ 120ms has nothing to do with the cardiac function grade,gender,age,heart failure,but relate with the incidence rate of malignant arrhythmia and mortality within 1 year,which can be used to evaluate disease severity and prognosis.