Use of left ventricular assist device associated with increased mortality compared to intra-aortic balloon pump in patients with cardiogenic shock from myocardial infarction

1. Use of an intravascular left ventricular assist device was associated with higher mortality in the short-term and 1 year after myocardial infarction complicated by shock in this retrospective study.

2. The mean cost associated with managing complications was also higher amongst patients treated with left ventricular assist device compared to intra-aortic balloon pump.

Level of Evidence Rating: 2 (Good)

Study Rundown: Cardiogenic shock is the most common cause of death after myocardial infarction (MI) and may be secondary to a number of structural and/or functional ischemic changes. Although cardiac surgery may be required for definitive management of cardiogenic shock in some cases, temporizing measures such as an intra-aortic balloon pump (IABP) can stabilize patients significantly in the interim and improve mortality outcomes. Recently, percutaneous supportive measures have piqued interest as alternative means of providing mechanical circulatory support, one example being left ventricular assist devices (LVAD). This study sought to directly compare IABP to LVAD in patients who experienced cardiogenic shock following MI, primarily assessing mortality outcomes up to 1 year after the index event.

A total of 3077 patients were included in this study; 27.9% received an LVAD and 72.1% received an IABP. The proportion of patients receiving LVAD compared to IABP increased during the study period from 2015 to 2019. Additionally, patients receiving LVAD were more likely to be comorbid than those with IABP. Analysis of a propensity-matched cohort demonstrated that LVAD use was associated with significantly higher in-hospital mortality than IABP, as well as greater rates of significant bleeding within 30 days. At 1 year from MI, the rate of mortality, significant bleeding and renal replacement therapy were higher in the LVAD group than the IABP group. The costs associated with caring for LVAD patients were also higher than the IABP group for the index hospitalization as well as at 30 days and 1-year post-MI.

The present study by Miller et al demonstrated unequivocally that IABP is a superior option compared to LVAD in managing cardiogenic shock following MI. Both morbidity and mortality outcomes were superior in the IABP group, as were cost-effectiveness outcomes. A major strength of this study is the large sample size and longitudinal data collection. However, a primary limitation is the reliance on administrative data collected retrospectively which relies on several assumptions and therefore may introduce further bias. Clinically relevant trials should be conducted in the future to assist in decision making and improvement of patient outcomes.

Click here to read this study in JAMA Internal Medicine

Click to read an accompanying editorial in JAMA

Relevant reading: Intra-aortic balloon pump: indications, guidelines and future directions

In Depth [retrospective cohort study]: Administrative databases collecting medical claims from approximately 60 million patients in 14 US states were used in this study. Eligible patients had 6 months of health insurance prior to their MI, underwent percutaneous coronary intervention for management, did not receive extracorporeal membrane oxygenation and had not previously had an IABP or LVAD on presentation to hospital.

Compared to patients who received IABP, those that received LVAD were more likely (p<0.05) to have the following comorbid conditions: hypertension, diabetes mellitus, heart failure, atrial fibrillation, peripheral vascular disease, chronic lung disease, and chronic kidney disease. Consequently, they were also more likely to have used hospital services in the 6 months preceding MI. The rate of in-hospital mortality amongst LVAD patients was 36.2% compared to 25.8% in the IABP group (odds ratio 1.63, 95% confidence interval 1.32-2.02). LVAD patients also had a higher rate of severe bleeding (20.3%) than IABP patients (15.5%; odds ratio 1.36, 1.06-1.75).

The hazard ratios for the following outcomes at 1 year also favored the IABP group: mortality (1.44, 1.21-1.71), severe bleeding (1.36, 1.05-1.75) and need for renal replacement therapy (1.95, 1.35-2.83). There were no significant differences in the rate of cerebral vascular events or repeat revascularization between the two groups. Finally, the mean cost associated with initial hospitalization in the LVAD group was higher ($60,279, 95% confidence interval $43,245-79,328) than the IABP group.

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