A NEW CRITERION COMBINING ST HR SLOPE AND DELTA-ST/DELTA-HR INDEX FORDETECTION OF CORONARY-ARTERY DISEASE IN PATIENTS ON DIGOXIN THERAPY/

We evaluated the clinical value of a new index combining Delta ST/Delt a heart rate (HR) index and ST/HR slope for diagnosing coronary artery disease (CAD) in patients on digoxin therapy. Exercise treadmill test s were performed by 72 patients on digoxin therapy. Simple HR-adjusted indexes of ST-segment depression during exercise (Delta ST/Delta HR i ndex) and the decline calculated from the final 12 data points relatin g ST-segment depression to HR (ST/HR slope) were determined. A new ind ex was obtained by subtracting the Delta ST/Delta HR index from the ST /HR slope. On thallium scintigraphy, 37 of the 72 patients showed reve rsible perfusion defects related to the diseased coronary artery. The new index derived from this ST-HR relation was 4.1 +/- 3.6 mu V/beats/ min in the ischemic group and 1.3 +/- 1.0 mu V/beats/min in the group of patients without ischemia (p <0.0001). An ST-HR relation greater th an or equal to 1.5 was found in 33 of the 37 patients in the ischemic group, and in 7 of the 35 patients without ischemia (p <0.0001). The s ensitivity of this criterion for prediction of myocardial ischemia was 89%, the specificity was 80%, and the predictive accuracy was 85%. Th us, this new ST-HR index is useful for detecting CAD in patients on di goxin therapy. (C) 1998 by Excerpta Medica, Inc.