Key result
A negative microvolt T-wave alternans test was associated with significantly better long-term survival (87.1% vs. 68.2%) compared to a non-negative test, despite a lower rate of ICD therapy.
Why the study?
A negative microvolt T-wave alternans test was hypothesized to identify patients unlikely to benefit from primary prevention ICD therapy.
Does a negative microvolt T-wave alternans test identify patients with LVEF ≤40% who are unlikely to benefit from primary prevention ICD therapy?
Cohort (n=651)
Yes
Does a negative microvolt T-wave alternans test identify patients with LVEF ≤40% who are unlikely to benefit from primary prevention ICD therapy?
Absolute Event Rate: 87.1% vs 68.2%
p-value: p=0.026
A negative microvolt T-wave alternans test identifies a subgroup of patients with LVEF ≤40% who have excellent long-term survival and are unlikely to benefit from primary prevention ICD therapy.
BACKGROUND We hypothesized that a negative microvolt T-wave alternans (MTWA) test would identify patients unlikely to benefit from primary prevention implantable cardioverter defibrillator (ICD) therapy in a prospective cohort. METHODSANDRESULTS Data were pooled from 8 centers where MTWA testing was performed specifically for the purpose of guiding primary prevention ICD implantation. Cohorts were included if the ratio of ICDs implanted in patients who were MTWA "non-negative" to patients who were MTWA negative was >2:1, indicating that MTWA testing had a significant impact on the decision to implant an ICD. The pooled cohort included 651 patients: 371 MTWA non-negative and 280 MTWA negative. Among non-negative patients, 62% underwent ICD implantation whereas only 13% of MTWA-negative patients received an ICD (P<0.01). Despite a substantially lower prevalence of ICDs, long-term survival (6.9 years) was significantly better among MTWA-negative patients (68.2% non-negative vs. 87.1% negative, P=0.026). CONCLUSIONS MTWA-negative patients had significantly better survival than MTWA non-negative patients, the majority of whom had ICDs. Despite a very low prevalence of ICDs, long-term survival among patients with left ventricular ejection fraction ≤40% and a negative MTWA test was better than in the ICD arm of any study to date that has demonstrated a benefit of ICDs. This provides further evidence that MTWA-negative patients are unlikely to benefit from primary prevention ICD therapy.
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Merchant et al. (2015) conducted a cohort in Primary prevention implantable cardioverter defibrillator (ICD) candidates (n=651). Negative microvolt T-wave alternans (MTWA) test vs. MTWA non-negative test (positive or indeterminate) was evaluated on Survival free of all-cause mortality (p=0.026). A negative microvolt T-wave alternans test was associated with significantly better long-term survival (87.1% vs. 68.2%) compared to a non-negative test, despite a lower rate of ICD therapy.
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