EXAGGERATED ATRIAL REPOLARIZATION WAVES AS A PREDICTOR OF FALSE-POSITIVE EXERCISE TESTS IN AN UNSELECTED POPULATION

The authors previously postulated that a markedly downsloping PR-segme nt might be a marker for exaggerated atrial repolarization waves and d emonstrated PR-segment appearance to be an independent predictor of a false positive exercise test. This study was conducted to determine th e sensitivity, specificity, and predictive value of markedly downslopi ng PR-segments for predicting false positive exercise tests. The study group consisted of 82 consecutive patients with a positive exercise t est (greater than or equal to 1.0 mm horizontal ST depression) and a n ormal resting electrocardiogram. Tests were predicted to be false posi tive based on previously defined criteria: (1) markedly downsloping PR -se,aments in two or more of leads II, III, and aVF and (2) exercise d uration 4 minutes or longer. Patients were then classified according t o available clinical information (coronary angiography and radionuclid e stress testing) into true positive (due to myocardial ischemia, n = 62) and false positive (n = 20) groups. The sensitivity, specificity, and predictive value of the PR-segment/exercise duration criterion for predicting a false positive test were 70, 74, and 47%, respectively. Patients with false positive tests also had higher heart rates (158 +/ - 16 vs 136 +/- 20 beats/min, P < .001) and less frequent chest pain ( 15 vs 46%, P = .017) during the exercise test. Patients with false pos itive exercise tests can be recognized by the achievement of a high pe ak exercise heart rate, the absence of exercise-induced chest pain, an d the appearance of markedly downsloping PR-segments in the inferior l eads.