文摘

Purpose The selection of the optimal right ventricular (RV) pacing site remains unclear. We hypothesized that a normal paced QRS axis would provide a physiological ventricular activation and lead to a better long-term outcome. Methods We evaluated 187 patients who underwent a permanent pacemaker implantation and were dependent on RV pacing. The pacing sites were classified as the apex and non-apex according to the chest radiography. A paced QRS axis was defined as that between ?0° and 90°. Preservation of the left ventricular (LV) systolic function was defined as that with a Results The median follow-up period was 5.8?years (interquartile 3.9-.0). Radiographically, the RV leads were located in the apex (n--48, 79?%) or non-apex (n--9, 21?%). In the electrocardiogram, normal paced and abnormal paced QRS axes were observed in 28 patients (15?%) and 159 patients (85?%), respectively. The LV ejection fraction was decreased in the patients with an abnormal paced QRS axis (?0?±-0?%, P--.001), but not in those with a normal axis (0?±-?%, P--.80). The electrocardiographic determinant differentiated a preserved LV function (95?% vs. 35?%, log-rank P--.04). Among the patients with radiographically non-apical pacing, a normal paced QRS axis was an additional meaningful predictor of a preserved LV function after the pacemaker implantation (95?% vs. 24?%, log-rank P--.002). Conclusion Compared with the radiographic method, a normal paced QRS axis was associated with a preserved LV function.