Abstract 20441: Combined Assessment of Autonomic Tone and Cardiac Repolarization Identifies Patients With Better-Preserved Left Ventricular Systolic Function at High Risk of Death Following a Myocardial Infarction
Introduction: A left ventricular (LV) ejection fraction (EF) of ≤ 35% later after myocardial infarction (MI) is principally used to identify patients for implantable cardioverter defibrillator (ICD) therapy. Yet, most patients who die suddenly after MI have LVEFs > 35%. A variety of risk markers have been advocated to identify those at higher risk. Yet, there is a lack of multicenter data to support their use. The Risk Estimation Following Infarction Noninvasive Evaluation - ICD efficacy (REFINE ICD) trial is evaluating whether ICD therapy reduces mortality in post-MI patients with LVEFs of 36% to 50% plus BOTH abnormal cardiac depolarization (T wave alternans; TWA) & impaired autonomic tone (heart rate turbulence; HRT). This ongoing trial includes patients from North America, Europe & the Middle East. Those with both abnormal TWA & HRT are randomized (1:1) to an ICD vs. usual care. In Canada, subjects not eligible for randomization (i.e., normal TWA & / or normal HRT) are followed in a Registry.
Hypothesis: We hypothesized that Randomized subjects (i.e., BOTH abnormal TWA & impaired HRT) would have a higher risk of death vs. Registry subjects (i.e., one or both markers normal).
Methods: Subjects were evaluated 3 to 15 months after MI with a SEER 12 high resolution Holter. Holter data were transmitted to a central core laboratory & analyzed, blinded to clinical data & outcome. Commercial software (MARS) was used to assess TWA & HRT using published criteria.
Results: Of 694 subjects, 323 were in the Randomized & 371 in the Registry group. Both the Randomized & Registry groups were enrolled a mean of 7 months after MI, had similar mean ages (64 vs. 60 years) & baseline LVEFs (42% vs. 43%). Randomized subjects were more likely to have prominent heart failure symptoms (6% vs. 2%) & be female (22% vs. 11%). Of the 18 deaths in follow-up, 16 occurred in the Randomized group. The odds of death in Randomized subjects was 9.6 (95% confidence interval 2.8 to 32.5) fold higher vs. Registry subjects (p = 0.0004).
Conclusions: The presence of both abnormal cardiac depolarization & impaired autonomic tone in post-MI patients with better-preserved LV function identifies a group with a nearly 10-fold higher risk of death. The REFINE ICD study is testing whether ICD therapy can alter that risk.
Author Disclosures: D.V. Exner: Research Grant; Significant; Medtronic Inc., GE Healthcare, St. Jude Medical. Ownership Interest; Significant; Analytics for Life. K.M. Kavanagh: None. T.W. Hruczkowski: Research Grant; Modest; Medtronic Inc. A.S. Hersi: Research Grant; Significant; Medtronic Inc. B. Thibault: Research Grant; Significant; Medtronic Inc., St. Jude Medical. F. Philippon: Research Grant; Modest; Medtronic Inc., Sorin. R. Yee: Research Grant; Significant; Medtronic Inc.. M. Guertin: None. J. Healey: Research Grant; Modest; Medtronic Inc. A. Tang: Research Grant; Modest; Medtronic Inc. H. Huikuri: Research Grant; Significant; Medtronic Inc..
- © 2016 by American Heart Association, Inc.