QT dispersion and myocardial viability in patients after acute myocardial infarction.
BACKGROUND
In recent years QT dispersion (QTd) in post-infarct patients was estimated in many studies, but still little is known about its association with the presence of dysfunctional but viable myocardium.


OBJECTIVE
We investigated the relation between dispersion of QT interval and myocardial viability in patients after acute myocardial infarction (AMI).


METHODS
In 52 patients (mean age 67.2+/-11.7) treated thrombolytically because of AMI 12-lead ECG and low dose-high dose dobutamine echocardiography was performed on 14th day after treatment. QTd and regional myocardial contractility were estimated three times: at baseline, low dose dobutamine (LDD) (10-15 microg/kg per min) and high dose dobutamine (HDD) infusion (up to 40 microg/kg per min).


RESULTS
Patients with viable myocardium had lower baseline QTd than patients with only necrosis in infarct zone. Significant increase in QTd was shown during LDD and HDD both in patients with and without myocardial viability. During infusion of HDD QTd was significantly higher in patients with myocardial ischemia. The greatest percentage increase of QTd at HDD was shown in patients with biphasic response to dobutamine infusion i.e. with myocardial viability evidenced at LDD and myocardial ischemia at HDD.


CONCLUSIONS
Patients with preserved myocardial viability had lower QTd values compared to those with similar left ventricular dysfunction but caused only by post-infarction necrosis. Ischemia evoked on 14th day after AMI was accompanied by greater increase in QTd in patients with myocardial viability in infarct region than in patients without. It may be one of the reasons of greater risk of serious ventricular arrhythmias in such patients during myocardial ischemia.
Kosmala
Wojciech
W
Cardiology Department, Klinika Kardiologii Akademii Medycznej we Wroclawiu, ul. Pasteura 4, Medical University, 50-367 Wroclaw, Poland. kosmw@kard.am.wroc.pl
Przewlocka-Kosmala
Monika
M
Halawa
Bogumil
B
D000368:Aged; D025401:Echocardiography, Stress; D004562:Electrocardiography; D005260:Female; D006321:Heart / Q000503:physiopathology; D006329:Heart Conduction System / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000150:complications / Q000175:diagnosis / Q000503:physiopathology*; D011446:Prospective Studies; D014022:Tissue Survival / Q000502:physiology*; D018754:Ventricular Dysfunction / Q000175:diagnosis / Q000209:etiology / Q000503:physiopathology*