Significance of the QX/QT Ratio and the QT Ratio (QTr) in the Exercise Electrocardiogram

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Abstract
Recently, a junctional depression of small amplitude (less than 2 mm.) of the ST segment was considered to be a positive or equivocal result for the electrocardiographic exercise test if the QX/QT ratio was ⪖ 50 per cent or the QTr ⪖ 1.08. In 150 normal, young students with no clinical evidence of heart disease, a junctional depression of the ST segment with a QX/QT ratio ⪖ 50 per cent or a QTr ⪖ 1.08 or both, was observed in 22 per cent. These observations, supported by other published reports concerning the QX/QT ratio and the QTr, indicate that these criteria are not reliable for the determination of a positive electrocardiographic exercise test.