Q. What is ST Heart Rate Index?
To calculate the index, the maximum ST depression is divided by the Delta heart rate (difference between the resting and maximum heart rate). As the calculation is very simple and not so dependent on a more gradual protocol, it has a considerable utility. It is important to remember that ST depression should be measured in fractions of a millimeter. When using an index of greater than 1.6 to identify ischaemia they report a sensitivity of 90 per cent and a specificity of 95 per cent.