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


METHODS
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.


RESULTS
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.


CONCLUSIONS
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.
Department of Cardiology, Akademiska Hospital, 751 85 Uppsala, Sweden. milos.kesek@zeta.telenordia.se
Milos
M
Kesek
Tomas
T
Jernberg
Bertil
B
Lindahl
Anders
A
Englund
D000368:Aged; D000787:Angina Pectoris / Q000175:diagnosis* / Q000401:mortality; D004562:Electrocardiography / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000503:physiopathology; D009204:Myocardial Revascularization; D011237:Predictive Value of Tests; D011379:Prognosis; D011446:Prospective Studies; D012307:Risk Factors; D012815:Signal Processing, Computer-Assisted; D013223:Statistics as Topic