Objective: To explore the relationship among heart rate turbulence (HRT), QT dispersion (QTd) and heart function in patients with dilated cardiomyopathy (DCM) and assess its clinical value.
Methods: A total of 81 DCM patients with ventricular premature contraction (VPC) were divided into two groups according to heart function: Group A (NYHA class I-II, n=34) and Group B (NYHA class III-IV, n=47). Thirty out-patient control cases were chosen from those undergoing regular physical examination. 24 hour holter was performed to monitor turbulence onset (TO) and turbulence slope (TS). Electrocardiogram (ECG) was used to assess QTd. Meanwhile left ventricular ejection fraction (LVEF), left ventricular end-diastolic dimension (LVEDD), E and A-wave peak velocities, E/A were measured by echocardiogram. After a comparison of all indicators in each group, an investigation was conducted to discern the relationship among HRT, QTd and heart function.
Results: Compared with normal group, TO significantly increased in DCM A and B group: [0.38 (-0.99-1.85)% vs 1.82 (0.02-3.92)% vs (-4.03±3.48)%, P<0.01]. TS significantly decreased while QTd increased. The trend of QTd addition was apparent along with heart failure. TO was negatively correlated with LVEF (r=-0.701, P<0.05) but positively correlated with LVEDD (r=0.621, P<0.05). There was no correlation with E and A-wave peak velocities. TS and QTd also had an obvious correlation with LVEF and LVEDD (all P<0.05).
Conclusions: HRT is dramatically blunted in DCM patients and has a certain correlation with cardiac dysfunction. A combined test of HRT and QTd is a sensitive and indirect index in assessing autonomic nerve functions. It has a high clinical value of predicting the prognosis.