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Comparison of Microvolt T Wave Alternans With Invasive and
Noninvasive Risk Stratifiers for Sudden Cardiac Death in Hypertrophic
Cardiomyopathy
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Presentation Start/End Time:
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Tuesday, Apr 01, 2008, 10:00 AM -11:00 AM
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Topic:
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ECG/Ambulatory Monitoring Signal Averaging
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Author Block:
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Frank Cuoco, Valerian
Fernandes, Christopher D. Nielsen, J. Lacy Sturdivant, Robert B. Leman, J.
Marcus Wharton, William H. Spencer, Michael R. Gold, Medical University of
South Carolina, Charleston, SC
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Keywords:
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Cardiomyopathies,
hypertrophic,Electrophysiology,Sudden death
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Introduction: Microvolt T-wave
alternans (TWA) and electrophysiology studies (EPS) are commonly used to
assess arrhythmia vulnerability in diverse patient populations. However,
nonarrhythmic clinical parameters are typically used to risk stratify for
sudden death (SCD) among patients with hypertrophic cardiomyopathy (HCM).
The relationship between arrhythmia measures and these risk factors (RFs)
is not well studied.
Methods: We evaluated 30 patients with HCM who underwent alcohol
septal ablation and were referred for EPS. The traditional RFs for SCD were
assessed, including a family history of SCD, syncope, marked septal
thickness, and abnormal blood pressure response during exercise. TWA was
performed in all pts prior to EPS.
Results: The mean age of the cohort was 50±13 years, 60% were male,
and they had 1.3±1 RFs for SCD. Positive (pos), negative (neg), and
indeterminate (ind) TWA results were 27%, 57%, and 17%, respectively. Six
patients (20%) had neg EPS, while 24 patients (80%) had pos EPS. In the TWA
neg group, 88% had pos EPS, whereas in the TWA non-neg (pos + ind) group,
69% had a pos EPS (p=0.36, Fisher's exact test). The table shows the
relationship between TWA and EPS with the traditional RFs for SCD in HCM.
Conclusions: TWA does not predict the results of EPS, and neither
TWA nor EPS are associated with traditional RFs for SCD in patients with
HCM. EPS was frequently positive and likely a nonspecific finding. Long
term follow-up is needed to assess if TWA predicts arrhythmic events.
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Traditional RFs for SCD in HCM - EPS
vs. TWA (all p-val NS using Fisher''s exact/student-t tests)
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Septal
Thickness (cm)
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Abnormal
BP Response
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Syncope/Near-syncope
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Family
History of SCD
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Total
Risk Factors
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EPS
Pos (n=24)
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2.4
± 0.6
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48%
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46%
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25%
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1.4
± 1.1
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EPS
Neg (n=6)
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2.3
± 0.4
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17%
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50%
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17%
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0.8
± 1.0
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TWA
Neg (n=17)
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2.3
± 0.5
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40%
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35%
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18%
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1.1
± 1.1
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TWA
Non-Neg (n=13)
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2.3
± 0.7
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42%
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62%
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31%
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1.5
± 1.0
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Learning Objective 1:
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assess the value of TWA testing in patients
with hypertrophic cardiomyopathy
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Learning Objective 2:
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describe the relationship between invasive,
non-invasive and clinical risk stratifiers for sudden cardiac death in
patients with hypertrophic cardiomyopathy
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