Early vs Late Impella® Device Support is Associated with a Better Survival Benefit in AMICS: A Meta-Analysis
- In patients with acute myocardial infarction complicated by cardiogenic shock (AMICS), early mechanical circulatory support with the Impella® device is associated with a greater survival advantage compared with post-revascularization support.
According to a meta-analysis by Flaherty et al, the initiation of early Impella® support before revascularization is associated with a survival benefit among patients with acute myocardial infarction complicated by cardiogenic shock (AMICS).1
Investigators pooled outcomes data from 3 studies which assessed early Impella support initiated prior to revascularization in AMICS: an exploratory analysis of a randomized-controlled trial (n = 24), findings derived from a retrospective, global catheter-based ventricular assist device registry (n = 287), and a single-center report (n = 68).2,3,4
Early Impella device support was defined as the placement of the Impella device prior to revascularization/early-on during angiography, whereas late support was defined as support initiated immediately following revascularization. The primary outcome was comprised of either 30-day or in-hospital mortality.
Prior to Impella device support, approximately 49% of patients in this pooled analysis had cardiac arrest at presentation. Additionally, 82% required inotropes and 81% were indicated for ventilator support.
Compared with late Impella support, the meta-analysis of these different forms of data suggests that early Impella initiation in AMICS patients reduced 30-day or in-hospital mortality by approximately 48%. Overall, patients receiving early Impella support in the 3 studies experienced a survival benefit that was considered statistically significant (risk ratio: 0.52; 95% confidence interval: 0.31 to 0.88, I2 = 0%; P=0.01).
“Our results are in agreement with the rationale from preclinical work performed in animal models demonstrating that early initiation of Impella provides effective left ventricular unloading, maintains adequate systemic and coronary perfusion, [and] decreases endothelin release and calcium overload,” concluded the investigators. “This [helps] prevent the downward spiral that may otherwise ensue with organ hypoperfusion, systemic inflammatory response, and multiorgan dysfunction leading to death.”
Clinical Relevance and Study Limitations
Although this study demonstrates a significant survival benefit of early vs late Impella support, it fails to establish causation. In addition, the lack of a comparison group as well as the potential for known and unknown confounders due to variability in the patient population slightly limits the findings of this meta-analysis.
Despite these limitations, the Flaherty meta-analysis validates previous research, which demonstrates associations between Impella support and hemodynamic improvement, infarct size reduction, and minimization of reperfusion injury.
In a small study by Kapur et al, the use of mechanical support for reducing left ventricular (LV) wall stress prior to reperfusion was associated with a greater percent reduction of infarcted LV myocardium vs no support (49±14% vs 28±7%, respectively; P=0.03).5 An animal study also confirmed the hypothesis that pre-reperfusion LV unloading with an LV assist device results in a greater reduction in myocardial infarct size vs post-reperfusion (P<0.05) and control (P=0.011).6
Further prospective randomized-controlled trials are necessary to further explore and validate the causative factors and survival advantage of early Impella support found in this meta-analysis.
- Flaherty MP, Khan AR, O'Neill WW. Early Initiation of Impella in Acute Myocardial Infarction Complicated by Cardiogenic Shock Improves Survival: A Meta-Analysis. JACC Cardiovasc Interv. 2017;10(17):1805-1806.
- Ouweneel DM, Eriksen E, Sjauw KD, et al. Percutaneous Mechanical Circulatory Support Versus Intra-Aortic Balloon Pump in Cardiogenic Shock After Acute Myocardial Infarction. J Am Coll Cardiol. 2017;69(3):278-287.
- Basir MB, Schreiber TL, Grines CL, et al. Effect of Early Initiation of Mechanical Circulatory Support on Survival in Cardiogenic Shock. Am J Cardiol. 2017 Mar 15;119(6):845-851.
- Schroeter MR, Köhler H, Wachter A, et al. Use of the Impella Device for Acute Coronary Syndrome Complicated by Cardiogenic Shock - Experience From a Single Heart Center With Analysis of Long-term Mortality. J Invasive Cardiol. 2016 Dec;28(12):467-472.
- Kapur NK, Paruchuri V, Urbano-Morales JA, et al. Mechanically unloading the left ventricle before coronary reperfusion reduces left ventricular wall stress and myocardial infarct size. Circulation. 2013;128(4):328-336.
- Achour H, Boccalandro F, Felli P, et al. Mechanical left ventricular unloading prior to reperfusion reduces infarct size in a canine infarction model. Catheter Cardiovasc Interv. 2005 Feb;64(2):182-192.
To learn more about the Impella® platform of heart pumps, including important risk and safety information associated with the use of the devices, please visit: abiomed.com/important-safety-information