QT dispersion correlates to myocardial viability assessed by dobutamine stress echocardiography in patients with severely depressed left ventricular function due to coronary artery disease.
BACKGROUND
QT dispersion is prolonged in numerous cardiac diseases, representing a general repolarization abnormality.


OBJECTIVE
To evaluate the influence of viable myocardium on QT dispersion in patients with severely depressed left ventricular (LV) function due to coronary artery disease.


RESULTS
103 patients with ischemic cardiomyopathy (LV ejection fraction [EF]: 25+/-6%) were studied. Patients underwent 12-lead electrocardiography to assess QT dispersion, and two-dimensional echocardiography to identify segmental dysfunction. Dobutamine stress echocardiography (DSE) was then performed to detect residual viability. Resting echo demonstrated 1260 dysfunctional segments; of these, 476 (38%) were viable. Substantial viability (> or =4 viable segments on DSE) was found in 62 (60%) patients. QT dispersion was lower in these patients, than in patients without viability (55+/-17 ms vs. 65+/-22 ms, P=0.012). Viable segments negatively correlated to QT dispersion (r=-0.333, P=0.001). In contrast, there was no correlation between LVEF and QT dispersion (r=-0.001, P=NS).


CONCLUSIONS
There is a negative correlation between QT dispersion and the number of viable segments assessed by DSE. Patients with severely depressed LV function and a low QT dispersion probably have a substantial amount of viable tissue. Conversely, when QT dispersion is high, the likelihood of substantial viability is reduced.
Thoraxcenter, Department of Cardiology, Erasmus Medical Center, Rotterdam, The Netherlands.
Manolis
M
Bountioukos
Arend F L
AF
Schinkel
Don
D
Poldermans
Vittoria
V
Rizzello
Eleni C
EC
Vourvouri
Boudewijn J
BJ
Krenning
Elena
E
Biagini
Jos R T C
JR
Roelandt
Jeroen J
JJ
Bax
D009202:Cardiomyopathies / Q000175:diagnosis*; D002316:Cardiotonic Agents / Q000494:pharmacology; D003324:Coronary Artery Disease / Q000150:complications / Q000175:diagnosis*; D004280:Dobutamine / Q000494:pharmacology; D004452:Echocardiography; D025401:Echocardiography, Stress; D004562:Electrocardiography; D005260:Female; D006329:Heart Conduction System / Q000187:drug effects / Q000503:physiopathology*; D006352:Heart Ventricles / Q000187:drug effects; D006801:Humans; D008297:Male; D011446:Prospective Studies; D013318:Stroke Volume; D018487:Ventricular Dysfunction, Left / Q000175:diagnosis* / Q000209:etiology
D002316:Cardiotonic Agents; D004280:Dobutamine