IDENTIFICATION OF FALSE POSITIVE EXERCISE TESTS WITH USE OF ELECTROCARDIOGRAPHIC CRITERIA - A POSSIBLE ROLE FOR ATRIAL REPOLARIZATION WAVES

[摘要] Atrial repolarization waves are opposite in direction to P waves, may have a magnitude of 100 to 200-mu-V and may extend into the ST segment and T wave. It was postulated that exaggerated atrial repolarization waves during exercise could produce ST segment depression mimicking myocardial ischemia. The P waves, PR segments and ST segments were studied in leads II, III, aVF and V4 to V6 in 69 patients whose exercise electrocardiogram (ECG) suggested ischemia (100-mu-V horizontal or 150-mu-V upsloping ST depression 80 ms after the J point). All had a normal ECG at rest. The exercise test in 25 patients (52% male, mean age 53 years) was deemed false positive because of normal coronary arteriograms and left ventricular function (5 patients) or normal stress single photon emission computed tomographic thallium or gated blood pool scans (16 patients), or both (4 patients). Forty-four patients with a similar age and gender distribution, anginal chest pain and at least one coronary stenosis greater-than-or-equal-to 80% served as a true positive control group. The false positive group was characterized by 1) markedly downsloping PR segments at peak exercise, 2) longer exercise time and more rapid peak exercise heart rate than those of the true positive group, and 3) absence of exercise-induced chest pain. The false positive group also displayed significantly greater absolute P wave amplitudes at peak exercise and greater augmentation of P wave amplitude by exercise in all six ECG leads than were observed in the true positive group. Multivariable analysis revealed that exercise duration (p = 0.0001) and downsloping PR segments in the inferior ECG leads (p = 0.0004) were independent predictors of a false positive test. The combination of downsloping PR segments in two of three inferior leads plus either exercise duration greater-than-or-equal-to 4 min or peak heart rate greater-than-or-equal-to 125 beats/min identified false positive tests with a sensitivity of 84% and a specificity of 86% to 89%. These results provide ECG criteria for predicting a false positive exercise test and support the hypothesis that exaggerated atrial repolarization waves may be a cause of a false positive exercise test.

[发布日期] 1991-07-01