QT dispersion and viable myocardium in patients with prior myocardial infarction and severe left ventricular dysfunction.
BACKGROUND
QT dispersion (QTd) has been found to correlate to the amount of viable myocardium in patients with Q-wave myocardial infarction and well-preserved LV function. However, this relationship is unknown in patients with severe left ventricular dysfunction.


METHODS
Thirty-four patients with prior large myocardial infarction and severe left ventricular dysfunction underwent Tc-99m sestamibi single photon emission cardiac tomography (SPECT) and F-18 fluorodeoxyglucose (FDG) SPECT. Viability was defined as a defect relative count density (DCD) of at least 20% greater on FDG SPECT. QTd, corrected QT dispersion (QTcd), and QT coefficient of variation (cv) in patients with viable myocardium was compared to those without viable myocardium in the infarct area.


RESULTS
Thirteen patients were excluded from analysis for poor FDG images or inadequate ECG tracings. Of the remaining patients, 10 (48%) were found to have viability on FDG SPECT. QTd, QTcd, and QTcv in patients with viability were: 58 +/- 22 ms, 61 +/- 23 ms, and 4.81 +/- 1.76%, respectively, which did not differ significantly from those in patients without viability (QTd = 56 +/- 14 ms, QTcd = 70 +/- 16 ms and Qtcv = 5.06 +/- 1.20% [P = NS]). Moreover, neither FDG defect size, nor LVEF correlated with QTd.


CONCLUSIONS
This study indicates no relationship between QTd and viability in patients with myocardial infarction and severe left ventricular dysfunction.
Li
Vuy Hun
VH
Division of Cardiology, St. Luke's-Roosevelt Hospital Center, 1111 Amsterdam Ave., New York, NY 10025, USA. jss7@columbia.edu
Dorbala
Sharmila
S
Narula
Dhiraj
D
DePuey
Gordon
G
Steinberg
Jonathan S
JS
D000368:Aged; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000503:physiopathology*; D011446:Prospective Studies; D013318:Stroke Volume; D017256:Technetium Tc 99m Sestamibi; D015899:Tomography, Emission-Computed, Single-Photon; D018487:Ventricular Dysfunction, Left / Q000000981:diagnostic imaging / Q000503:physiopathology*
D019788:Fluorodeoxyglucose F18; D017256:Technetium Tc 99m Sestamibi