Abstract 16255: Wearable Cardioverter Defibrillator Treatment Characteristics and Outcomes in Recent Myocardial Infarction Patients With Heart Failure

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Introduction: Previous studies report patients (pts) with acute myocardial infarction (MI) complicated by heart failure (HF) have poorer outcomes than non-ischemic HF pts. We determined the clinical and arrhythmia characteristics and outcomes in recent (< 40 days) MI pts with HF versus non-ischemic (NICM) HF pts treated by the wearable cardioverter defibrillator (WCD). Methods: WCD pts with a medical history of HF treated for VT or VF between 1/2007 and 11/2013 were identified from the manufacturer-maintained registry. Pts were classified as recent MI if they were identified as having a “recent MI with ejection fraction (EF) ≤ 35%” or given an ICD-9 diagnostic code of 410.xx (acute MI). Pts were classified as non-ischemic if they had no epicardial coronary vessels with ≥ 75% stenosis, no history of myocardial infarction, and no coronary revascularization. Data were reviewed for demographics, ECG recordings, and 24-hour survival. Electrical storm was defined as 3 or more unique VT/VF events requiring WCD therapy over a 24-hour time period. Results: Total of 346 pts met the study criteria, with 56% classified as recent MI with HF (MI-HF). MI-HF group was more likely to have risk factors for ischemic disease such as being older, male, hypertensive, diabetic, etc. (Table). The mean difference in EF between the two groups was less than 5%. MI-HF pts were 1.7 times more likely to be in VT versus VF at initial shock and 2.1 times more likely to have an electrical storm. Conversion of VT/VF events to slower rhythms by WCD treatment shock was 98% or greater in both groups. 24-hour post-treatment survival was 92% for all pts, with no difference between the two groups. CONCLUSIONS: Recent MI pts with HF who were treated by the WCD were likely to be older and male, with risk factors for ischemic disease. In addition, MI-HF pts exhibited increased incidence of VT versus VF events and electrical storm. The WCD was effective in terminating arrhythmic events with a high post-treatment survival in both groups.