BACKGROUND: It is known that prolonged QRS duration (QRSd) in a 12-lead ECG is associated with decreased left ventricular (LV) systolic function in patients with dilated cardiomyopathy. Development of LV systolic dysfunction and prolongation of paced QRSd are often observed in patients with permanent pacemakers (PPM). However, the significance of prolonged paced QRSd in patients with PPM is not determined. METHODS: We studied sixty-four patients (male:female=27:37, mean age=57.6+/-15.4 years) who had been on PPM (DDD: 15, VDD: 18, VVI: 31) for more than one year (mean: 68.2+/-44.0 months). LV function was normal before implantation of PPM. The 12-lead ECG and echocardiography were recorded prior to implantation, immediately after implantation and at the last follow-up. RESULTS: Paced QRSd did not significantly increase during the follow-up period. LVEF at the last follow-up (LVEF-FU) was significantly lower than that prior to implantation (59.3+/-11.5% vs. 64.9+/-10.1%, p<0.001). Eleven (17.2%) patients developed LV systolic dysfunction (LVEF<50%) during the follow-up period. Paced QRSd at the last follow-up and diabetes mellitus were correlated with LV systolic dysfunction (R2=0.302, p<0.001). There was a significant negative correlation between the paced QRSd and LVEF-FU (r=-0.451, p<0.01) and between change of paced QRSd and that of LVEF during follow-up (r=-0.419, p<0.01). LVEF-FU was reduced more in patients with paced QRSd >or=180 ms than in patients without (44.4+/-12.0% vs. 61.7+/-9.5%, p<0.001). In predicting LV systolic dysfunction with the paced QRSd (cut-off value: 180 ms), sensitivity, specificity, positive and negative predictive values were 60.0%, 88.7%, 50.0% and 99.2%, respectively. The paced QRSd at the last follow-up was significantly correlated with paced QRSd immediately after implantation (r=0.542, p<0.01). CONCLUSION: LV systolic dysfunction after long-term right ventricular apical pacing may develop. Prolongation of paced QRSd 180 ms during follow-up may suggest development of LV systolic dysfunction. New technologies to minimize prolongation of paced QRSd should be investigated to prevent LV systolic dysfunction after permanent ventricular pacing.
Cardiomyopathy, Dilated ; Diabetes Mellitus ; Echocardiography ; Electrocardiography ; Follow-Up Studies ; Humans ; Sensitivity and Specificity ; Ventricular Dysfunction, Left* ; Ventricular Function