The Effect of Coronary Stenting on Ventricular Activation Time in Coronary Artery Disease

BACKGROUND AND OBJECTIVES: The ventricular activation time (VAT) is increased in both ventricular hypertrophy and bundle branch block. It is also known that the VAT is increased in myocardial ischemia due to the development of depolarization abnormality. However, little is known about the changes in the VAT on body surface electrocardiography following coronary stenting in patients with ischemic heart disease. The purpose of this study was to evaluate the clinical significance of VAT following coronary stenting by assessing the changes in the VAT during the 6 months following coronary stenting in patients with ischemic heart disease. SUBJECTS AND METHODS: The VAT was measured in 92 patients who had underdone coronary stenting due to of significant coronary artery stenosis on coronary angiography. The electrocardiography was recorded with a high paper speed at pre-stenting, immediate after and at 1 and 6 months after coronary stenting. RESULTS: The VAT was significantly decreased during the 6 month follow-up following coronary stenting (pre-stenting ; 45.9 +/-5.9 msec, immediate after stenting ; 38.5+/-2.7 msec, after 1 month ; 38.8+/-2.8 msec and after 6 months ; 38.8+/-2.5 msec, p<0.05). The VAT dispersion was significantly decreased during the 6 month follow-up following coronary stenting in the patients with one vessel disease (p<0.05), but not with two vessels disease. CONCLUSION: Coronary stenting significantly decreased the VAT during the 6 month follow-up. We would conclude that coronary stenting relieves depolarization abnormalities caused by myocardial ischemia, and improves the intraventricular conduction velocity. However, further studies are needed to assess the usefulness of VAT in evaluating myocardial ischemia.

The change in QT dispersion on treadmill exercise test after coronary stenting / 대한내과학회지

BACKGROUND: QT dispersion (QTd) represents inhomogeneous ventricular repolarization. Increased QTd has been reported to be associated with ischemic heart disease and sudden cardiac death. Successful percutaneous coronary angioplasty (PTCA) produces a favorable recovery of inhomogenous repolarization and reduces QTd. Although treadmill exercise test is commonly used for follow-up test after PTCA, limited data are available about QTd during treadmill test. The purpose of this study was to evaluate the change in QTd and determine its clinical role in follow-up treadmill exercise test after coronary stenting. METHODS: 41 patients with significant coronary artery disease underwent successful coronary stenting, while 46 patients were medically treated. Treadmill exercise test was performed to compare QTd between two groups as a follow-up test at 6 months after coronary stenting and medical therapy. Treadmill exercise test was recorded in pre-test, peak exercise, and recovery 2 minutes phase. QTd and corrected QT dispersion (QTcd) were measured in these ECGs using a digitizer. RESULTS: Coronary stenting significantly reduced QTd and QTcd at 6 months after coronary stenting. QTd and QTcd did not show significant difference between coronary stenting and medical therapy group at initial EKG before treatment. After coronary stenting, QTd and QTcd were significantly reduced than those of medical therapy group. And the changes in QTd and QTcd were more marked at peak exercise (28.2+/-11.9 and 39.3+/-16.2 msec in coronary stenting group vs 40.4+/-20.5 and 57.8+/-30.0 msec in medical therapy group). Lesion location and diseased vessel number were not associated with changes in QTd and QTcd. CONCLUSION: Coronary stenting reduced QTd and QTcd significantly in follow-up treadmill exercise test. Coronary stenting appears to be more effective to relieve myocardial ischemia and to improve inhomogenous ventricular repolarization than medical therapy. The measurement of QTcd during treadmill exercise test may be a useful index to evaluate myocardial ischemia after coronary stenting. Clinical relevance of these finding will require further study.

Heart Rate Recovery in Coronary Artery Disease and the Changes of Exercise Parameters after Coronary Stenting

BACKGROUND AND OBJECTIVES: The recovery of the normal heart rate immediately after exercise is a function of vagal reactivation. An attenuated heart rate recovery during the first minute after graded exercise is believed to be a marker of reduced parasympathetic activity and has been proven to be an independent predictor of overall mortality. However, the clinical significance of an abnormal heart rate recovery in coronary artery disease and the changes in the exercise parameters after coronary stenting have not been fully evaluated. Subjects and Methods: The study population included 53 patients with a significant coronary artery stenosis and 25 subjects with a normal coronary artery. All underwent a treadmill exercise test prior to coronary angiography. The differences in the heart rate recovery and the Duke treadmill score between two groups were investigated. After coronary stenting, changes in the exercise parameters were evaluated during the follow-up treadmill exercise test in 22 coronary artery disease patients. RESULTS: The frequencies of abnormal heart rate recovery (12% vs 38.3%, p=0.014) and a moderate to high risk Duke treadmill score (4% vs 21.3%, p=0.034) were significantly higher in the coronary artery disease group. The frequencies of these parameters were also significantly higher in the multivessel disease group than the single vessel disease group. After coronary stenting, most of the exercise parameters showed no significant changes but the Duke treadmill score improved significantly (p=0.038). CONCLUSION: The frequency of abnormal heart rate recovery was significantly higher in the coronary artery disease group. The Duke treadmill score was significantly improved and is thought to be a useful follow up parameter after coronary stenting.