Soliman et al used relative change in QT dispersion (relative change in QTd) to detect a patient with coronary restenosis following a successful coronary angioplasty. The authors are from Wake Forest University and the National Heart Institute at Imbaba, Egypt.


The QT intervals were corrected for heart rate using the formula of Fridericia.



(1) baseline QTd (after successful percutaneous coronary angioplasty)

(2) current QTd


relative change in QT dispersion =

= ((current QTd) – (baseline QTd)) / (baseline QTd) * 100%



• A relative QTd >= 40% (or current QTd >= 1.4 times baseline) identified a patient who may develop coronary restenosis.



• The area under the ROC curve was 0.79.

• The sensitivity was 71% and specificity 83%.

• The positive predictive value was 90% but negative predictive value was 57%.


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