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QT interval dynamics predict mortality in high-risk patients after myocardial infarction
Ulrik Hintze1, Werner Vach, Hans Burchardt
1Department of Cardiology, Odense University Hospital, Denmark. hintze@dadlnet.dk
Objective:
The purpose of this study was to evaluate the prognostic properties of the QT/RR relationship in survivors of myocardial infarction with severe left ventricular dysfunction.
Design:
The QT/RR interval slope was assessed from 24-h electrocardiographic recordings obtained from 241 patients representative of survivors of an acute myocardial infarction with an ejection fraction < or =35%. During a median follow-up of 752 days, 63 patients died.
Results:
In a multivariate analysis QT/RR at night-time was an independent predictor of all-cause mortality. A linear all-cause mortality predictor score was calculated from age, ejection fraction, QRS duration and QT/RR night, allowing identification of a high-risk one-third of the patients with a relative risk of death at 4.0.
Conclusion:
This study demonstrates independent prognostic information of night-time QT/RR dynamics in patients at high risk after myocardial infarction. A linear predictor score calculated from age, ejection fraction, QRS duration and QT/RR night identifies a high-risk one-third of the patients with a 1-year mortality of 36% vs 9% in the remaining patients.