Clinical importance of late potential in patients with angina pectoris
Akiya, T.; Horinaka, S.; Arakawa, M.; Yamamoto, H.; Matsuoka, H.
Journal of Cardiology 29(4): 189-194
1997
ISSN/ISBN: 0914-5087 PMID: 9127834 Document Number: 471698
Angina pectoris, especially vasospastic angina, is associated with lethal ventricular tachycardia. The clinical importance of late potential in angina pectoris was assessed in 171 patients with angina-like pain. Patients were categorized into three groups based on coronary angiography. Patients in the exertional angina pectoris (AP) group exhibited at least 75% organic stenosis of a major coronary artery after intracoronary injection of a nitrate drug (82 patients). Patients in the chest pain syndrome (CPS) group had no significant organic stenosis of the coronary artery and the acetylcholine-loading test produced negative results (39 patients). Patients in the vasospastic angina (VSA) group had a positive acetylcholine-loading test (50 patients). When the filtered QRS duration was prolonged to above 130 msec and/or the root-mean-square voltage in the last 40 msec was below 15 microV in VCM-3000, the late potential was judged to be positive. The incidence of late potential was higher in the AP group (23.2%) and the VSA group (38.0%) than in the CPS group (7.7%) (p < 0.05, p < 0.01). Comparison of late potential incidence between patients with coronary vasospasm below 90% (group 1) and patients with above 90% (group 2) induced by the acetyl-choline-loading test in the VSA group showed more late potential in group 2 than in group 1 (84.2% vs 15.8%). Late potential was present in 19 (23.2%) patients in the AP group, but only 2 (10.5%) had under 90% degrees of coronary stenosis and the other 17 (89.5%) had greater than 90% degrees of stenosis. Thus, late potential was mainly observed in patients with severe organic stenosis. These results suggest that the origin of late potential is associated with inhomogeneous electrical excitation induced by frequent angina attack and the duration of total or near total occlusion. Strict clinical management is required for patients with VSA or AP associated with late potential.