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

ABSTRACT

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.