Abstract 309: Trends in LVAD Use and Outcomes Among Patients Admitted with Acute Myocardial Infarction

Abstract

Background: Mortality rates among patients with acute myocardial infarction (AMI) complicated by cardiogenic shock remain high. Implantation of left ventricular assist devices (LVAD) has become increasingly available since the approval of continuous flow devices in 2008 and in severe cases, may be used to prolong survival post AMI. Little is known about how the frequency of LVAD implantation and subsequent outcomes in AMI patients have changed over time. Methods: We used the National Inpatient Sample, a 20% stratified sample of all hospital discharges that uses scaled weights to approximate national estimates. We identified all patients with AMI (ICD9 code 410.1x) and LVAD implantation (ICD9 code 37.66) from 2006 through 2012.The primary outcome was in-hospital mortality. Baseline characteristics were compared over time using the chi-square test for categorical variables. Univariate logistic regression was used to examine the association between baseline characteristics and risk of mortality after LVAD. Results: The number of LVADs implanted for any indication increased from 713 to 2,960 during the study period whereas LVAD use among AMI patients remained stable (Figure). AMI patients who received an LVAD were predominately male and white and the average age was 56.3 years. The number of AMI patients receiving ECMO, Impella, or other short-term mechanical support devices as a bridge to LVAD increased over time whereas IABP use remained stable. Among patient and hospital factors studies, non-white race and later year of implantation were associated with lower mortality after LVAD. Use of other mechanical support devices was associated with higher mortality (OR 2.7, p=0.029). Post-LVAD mortality rates were higher for AMI compared to non-AMI patients but decreased for all patients over time: 57.1% to 21.2% for AMI patients (p <.0001) and 36.8% to 12.8% for patients without AMI, p < .0001). Conclusion: Among patients with AMI, LVAD use remains low and has not increased as has LVAD use for other indications. Although LVAD use in this population was initially associated with higher in-hospital mortality, our analysis suggests a narrowing of this gap. Future studies are needed to determine how long-term survival is affected and which patients are appropriate candidates for LVAD implantation after AMI.