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Presentation Number:
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924-123
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Abstract Title:
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QRS Duration and Microvolt T Wave Alternans Testing in Patients With
Ischemic Cardiomyopathy
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Presentation Start/End Time:
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Sunday, Mar 12, 2006, 3:30 PM - 4:30 PM
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Topic:
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Clinical Electrophysiology -Ventricular Arrhythmias
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Author Block:
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Theodore Chow, Syed Saghir, Cheryl Bartone, Terri Booth, Paul
S. Chan, Ohio Heart & Vascular Center, Cincinnati, OH, University of
Michigan, Ann Arbor, MI
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Background: Prior studies
assessing the relative prognostic utility of microvolt T-wave alternans
(MTWA) and QRS>120ms have been limited by small sample sizes and study
design limitations. These studies also suggested that MTWA was not
predictive in patients with QRS>120msec.
Objective: To determine the relative predictive value of MTWA and
QRS>120ms for mortality in patients with ischemic cardiomyopathy, and
assess whether QRS duration interacts with the prognostic accuracy of MTWA.
Methods: We developed a prospective database of 768 patients with
ischemic cardiomyopathy (LVEF<35%) and no prior history of
sustained ventricular arrhythmia, of which 392 (52%) received ICDs. Mean
follow up was 18+10 months. We assessed the degree to which a
non-negative (positive and indeterminate) MTWA test and a QRS>120ms
predicted mortality risk using stratified (by ICD status) Cox proportional
hazards analyses that controlled for demographic, clinical, and medication
treatment variables.
Results: In our cohort, 67% of patients had a non-negative MTWA test
and 32% had a QRS>120ms on ECG. Unadjusted Kaplan-Meier survival
estimates showed that both a non-negative MTWA [stratified log-rank
test=13.5; p=0.0002] and a QRS>120ms [stratified log-rank test= 9.7;
p=0.0018] were associated with lower survival probability. After
multivariable adjustment, MTWA remained an independent predictor of
mortality [stratified hazard ratio=2.24 (1.33, 3.76); p=0.0023], whereas
QRS>120ms was no longer predictive [stratified hazard ratio=1.51 (0.90,
2.51); p=0.12]. No significant interaction existed between ICD and MTWA
status (p=0.47) or between MTWA and QRS>120ms (p=0.25).
Conclusion: MTWA, but not QRS>120ms, is predictive of mortality
in patients with ischemic cardiomyopathy. QRS duration does not affect the
prognostic ability of MTWA.
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Keywords:
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Coronary artery disease,Sudden death,Ventricular arrhythmia
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