Abstract: Objective To observe the effect of coronary artery disease on QT dispersion (QTd). Methods The QTd and QTcd in 245 patients underwent percutaneous coronary angiography (CAG) were analyzed. It was evaluated The relations between the QTd and the degree of coronary stenosis and the number of disease vessels. Results The QTd and QTcd were significantly prolonged in patients with coronary artery stenosis than those in patients with normal coronary artery(P<0.001). The QTd and QTcd also showed difference between patients whose coronary artery stenosis were ≥70% and patients whose coronary artery stenosis were <70% and ≥50% (P<0.01). The QTd was positively correlated with coronary stenosis degree(r=0.84，P<0.05). The seriouser the degree of coronary stenosis was, the greater the QTd was. The QTd and QTcd of the patients with single and multiple vessel lesion showed no significant difference(P>0.05). Conclusion There is no relation between the number of disease coronary artery and the QTd.

Key words: QT dispersion