The Effect of Atrial Repolarization Waves on the Maximal Exercise Loading Test

BACKGROUND: The atrial repolarization waves might contribute to ST segment depression during the exercise loading test. As atrial repolarization waves are opposite in direction to P waves, they could shift the ST segment in the absence of myocardial ischemia. METHODS: The exercise test in 20 patients was seemed false positive because of normal coronary angiogram. Twenty-six patients with at least one coronary stenosis > or =50% served as a true positive group. The P waves, PR segments and ST segment were studied in leads II, III, aVF and V4 to V6 in those 46 patients whose exercise ECG suggested ischemia. RESULTS: The finding of steeply downsloping PR segment, particularly in the inferior ECG leads, in patients with longer exercise time and higher exercise heart rate might predict a false positive exercise test in those with a normal rest ECG and no apparent reason for a false positive test. The combination of downsloping PR segments in two of three inferior leads plus either exercise duration > or =5 min or peak heart rate > or =130 bests/min idenified false positive tests with a sesitivity of 75% and a specificity of 81% to 89%. CONCLUSIONS: Atrial repolarization waves might play a role in exercise induced ST segment depression.

Relation between Ischemia on Exercise Testing and on Holter Monitoring

BACKGROUND: The relation between treadmill exercise testing and ambulatory ST segment monitoring in detection of ischemia in patients with coronary artery disease has not been well established, with pathophysiologic mechanisms underlying the development of ischemia in the ambulatory setting not being well elucidated. This study was performed to determine the relation between myocardial ischemic indexes on exercise testing and on Holter monitoring. METHODS: We analized 25 patients with stable angina and angiographically documented coronary artery disease, who exhibited ischemia both on a Bruce protocol exercise test and on 24-hr Holter monitoring while receiving routine antianginal medications. RESULTS: Mean heart rate at the onset of 1mm ST segment depression during exercise testing(74.4 VS 114.1 beats/min, p<0.01). Overall the correlations between ischemic indexes on both test were weak. But heart rate at the onset of ischemic episodes during Holter monitoring had a good correlation with heart rate at 1mm ST depression during exercise test. And the number of ischemic episodes on Holter monitoring revealed a weak negative correlation with duration of exercise during treadmill test. CONCLUSION: Ischemic indexes on exercise testing cannot accurately predict ischemic indexes on Holter monitoring in patients with coronary artery disease. In that regard, Holter monitoring may provide other clinical information in addition to that obtained by exercise testing in selected patients.