QT dispersion measured by an automatic continuous method early in patients admitted for chest pain

There is a need for risk markers in patients with acute chest pain. QT dispersion (QTd) is a prognostic marker in several groups of patients. A problem with the manual measurement of QTd is operator dependency. This can be avoided by using an automatic method. We investigated QTd, derived from multiple automatic measurements, as a risk marker in a population with chest pain.

In 548 patients admitted to the coronary care unit for chest pain and nondiagnostic ECG, 12-lead ECG recordings were collected each minute during the initial 17 h. From recordings with > or =10 valid leads, mean QTd (QTdMean), QTd in the first satisfactory recording and estimates of variability of QTd were computed and correlated to outcome.

In the group with QTdMean > or =40 ms (n=277), 10 patients died during the initial 30 days; one patient died in the group with QTdMean <40 ms (n=271) (P=0.07). During follow-up (median 6 months), 19 vs. five patients died in each group (P=0.03). The figures for the triple endpoint death/myocardial infarction/revascularisation were 52 vs. 27 events during the initial 30 days (P=0.018) and 76 vs. 41 events during follow-up (P=0.003). QTd in the first recording did not predict new cardiac events.

QTd measured as the mean value of multiple recordings was found to be a powerful marker for cardiac events during follow-up. It was superior to the analysis of QTd in a single ECG. It can be used for the selection of low-risk patients, but was not effective in identifying high-risk patients.