Prognostic implication of redefining indeterminate microvolt T-wave alternans studies as abnormal or normal
Paul S Chan1, Cheryl Bartone, Terri Booth
1Division of Cardiology, University of Michigan, Ann Arbor, MI, USA. paulchan@umich.edu
American Heart Journal
|March 27, 2007
Summary
Indeterminate microvolt T-wave alternans (MTWA) test results in patients with ischemic cardiomyopathy show varied survival risks. Reclassifying these results improves the prognostic accuracy of MTWA testing for mortality risk.
Area of Science:
- Cardiology
- Electrophysiology
- Clinical Risk Stratification
Background:
- Microvolt T-wave alternans (MTWA) testing is used to assess arrhythmia risk.
- Prior studies often grouped indeterminate MTWA results as high-risk.
- Limited data exists on the prognostic impact of specific reasons for indeterminate MTWA results.
Purpose of the Study:
- To evaluate survival prognosis differences among patients with specific reasons for an indeterminate MTWA result.
- To determine if reclassifying indeterminate MTWA results improves predictive accuracy.
Main Methods:
- 768 patients with ischemic cardiomyopathy and LVEF ≤ 35% were enrolled.
- MTWA tests were categorized as positive, negative, or indeterminate (due to ectopy, inadequate heart rate, unsustained alternans, or noise).
- Multivariable Cox regression analyses assessed mortality risk based on indeterminate reasons.
Main Results:
- 21% of patients had indeterminate MTWA results.
- Indeterminate results due to ectopy or inadequate heart rate were linked to significantly higher all-cause and arrhythmic mortality.
- Reclassifying indeterminate results as abnormal (positive + ectopy/IHR) or normal (negative + unsustained alternans) enhanced MTWA's predictive power.
Conclusions:
- Heterogeneity exists in survival prognosis among patients with indeterminate MTWA studies.
- Reclassifying indeterminate MTWA results improves the overall predictive utility of the test for risk stratification.
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