Prognostic value of exercise-induced QT dispersion in patients after acute myocardial infarction.
BACKGROUND
Electrocardiographic exercise tests are widely recommended for patients before discharge after myocardial infarction, what justify the search for new variables which may improve their prognostic value. QT dispersion in 12 lead ECG reflects the heterogeneity of ventricular repolarisation. Increased QT dispersion is a noninvasive marker of ischaemia and electrical instability.


OBJECTIVE
Evaluation of the prognostic value of exercise-induced changes of QT dispersion in patients after an acute myocardial infarction.


METHODS
Heart rate limited treadmill exercise test according to modified Bruce was performed 14+/-5 days after infarction in 77 patients (age 56+/-11,8 female). QT dispersion was measured at rest and on peak exercise. Patients were followed up for mean 88 months.


RESULTS
QT dispersion was higher at peak exercise in those patients who died due to cardiovascular causes (n=8) or suffered from non-fatal myocardial infarction during follow-up (n=15), than in remaining group (71+/-20 vs 58+/-22 msec, p<0.01). At rest QT dispersion was similar in both groups (64+/-17 vs 66+/-20 msec, NS).


CONCLUSIONS
The lack of an exercise-induced decrease in QT dispersion identifies a subgroup of patients after myocardial infarction with a poor long-term prognosis.
Bednarz
Bronisław
B
Department of Cardiology, Postgraduate Medical School, Warsaw, Poland.
Wołk
Robert
R
Chamiec
Tomasz
T
Ceremuzyński
Leszek
L
D000368:Aged; D004562:Electrocardiography; D005080:Exercise Test; D005260:Female; D005500:Follow-Up Studies; D006329:Heart Conduction System / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000401:mortality* / Q000503:physiopathology*; D011237:Predictive Value of Tests; D011379:Prognosis; D012680:Sensitivity and Specificity; D013997:Time Factors