QT dispersion as a predictor of long-term mortality in patients with acute myocardial infarction and clinical evidence of heart failure.
BACKGROUND
QT interval dispersion is a marker of inhomogeneous ventricular repolarization, and therefore has the potential to predict re-entry arrhythmias. Following acute myocardial infarction, increased QT dispersion has been associated with a higher risk of ventricular arrhythmias. However, whether or not QT dispersion predicts prognosis post-acute myocardial infarction is not clear. We addressed this issue by analysing the AIREX study registry.


METHODS
AIREX was a follow-up study of 603 post-acute myocardial infarction patients who exhibited clinical signs of heart failure and were randomly allocated to ramipril or placebo. An interpretable 12-lead ECG obtained between day 0 and day 9 after the index infarction (median time 2 days) was available in 501 patients. We examined whether QT dispersion was a predictor of all-cause mortality in the AIREX study registry (mean follow-up 6 years).


RESULTS
QT dispersion measurements were significantly increased in patients who subsequently died (QT dispersion: 92.0 +/- 38.5 ms vs 82.7 +/- 34.3 ins. P=0.005; rate corrected QT dispersion: 105.7 +/- 42.7 ms vs 93.1 +/- 35.9 ms, P<0.001). Univariate analysis showed that QT dispersion as a predictor of all-cause mortality risk (QT dispersion: hazard ratio per l0 ms 1.05, [95% CI 1.02 to 1.09]. P= 0.004; rate corrected QT dispersion: 1-07 [1.03 to 1.10], P<0.001): an increase of 10 ms added a 5-7%, relative risk of death. QT dispersion remained an independent predictor of all-cause mortality risk on multivariate analysis (QT dispersion: 1.05 [1.01 to 1.09], P=0.027; rate corrected QT dispersion: 1.05 [1.01 to 1.09]. P=0.022).


CONCLUSIONS
QT dispersion. measured from Li routine 12-lead ECG following acute myocardial infarction complicated by heart failure provides independent information regarding the probability of long-term survival. However. the low sensitivity of this electrocardiographic marker limits its usefulness for risk stratification if used in isolation.
Spargias
K S
KS
Institute for Cardiovascular Research, University of Leeds, Leeds, U.K.
Lindsay
S J
SJ
Kawar
G I
GI
Greenwood
D C
DC
Cowan
J C
JC
Ball
S G
SG
Hall
A S
AS
D000368:Aged; D001145:Arrhythmias, Cardiac / Q000209:etiology* / Q000401:mortality* / Q000503:physiopathology; D016009:Chi-Square Distribution; D004562:Electrocardiography; D005260:Female; D005500:Follow-Up Studies; D006333:Heart Failure / Q000150:complications* / Q000401:mortality* / Q000503:physiopathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009203:Myocardial Infarction / Q000150:complications* / Q000401:mortality* / Q000503:physiopathology; D011237:Predictive Value of Tests; D011379:Prognosis; D016016:Proportional Hazards Models; D012042:Registries; D012680:Sensitivity and Specificity; D015996:Survival Rate