By Dr. Aswin Babu
Cardiogenic shock occurs in around 8% of cases of acute myocardial infarction (AMI) and is associated with a 30-day mortality of 40% and 1-year mortality of 50% 1. Except for early revascularisation of the culprit artery, no other treatments have been proven to provide a benefit in major adverse cardiac events. Given the deficiency of evidence advocating the routine use of intra-aortic balloon pump (IABP) and the superior haemodynamic benefits from left ventricular assist devices (LVAD), there has been a marked rise in the use of intravascular microaxial LVAD from 4.1% of cases of cardiogenic shock in 2012 to 19.9% of cases in 20172.
The Journal of American Medical Association (JAMA) recently published a retrospective, observational, propensity score-matched cohort study by Miller et al (2022) which compared the primary outcomes of death, stroke, severe bleeding, repeat revascularisation, renal replacement therapy (RRT) and cost effectiveness between intravascular microaxial LVAD and IABP in patients with cardiogenic shock after AMI. Out of a sample size of 3,077 patients, they were able to perform propensity matched scores on 817 individuals. Intravascular microaxial LVAD was associated with a significantly higher rate of in-hospital mortality with 63% of patients more likely to pass away in hospital (OR 1.63; 95% CI 1.32-2.02). This continued at both 30 days (OR 1.71, 95% CI, 1.37-2.13) and at 1 year (HR 1.44; 95% CI 1.21-1.71). Additionally, patients who received an intravascular microaxial LVAD had significantly elevated rates of severe bleeding and need for RRT alongside increased costs at index hospital admission with intravascular microaxial LVAD costing $50,000 when compared to the use of IABP.
Although these results are worrying for the routine use of common intravascular microaxial devices such as IMPELLA, one must be careful when extracting results from a retrospective, observational study solely based on data from insurance claims. Although propensity score matching was utilised, there is always the risk of residual confounding factors. In addition, patients in the LVAD arm may have been a sicker cohort of patients with worse haemodynamics and biochemical parameters and thus resulting in worse outcomes.
However, it is troubling that other retrospective propensity score matched studies have also found similarly significant disadvantages of intravascular microaxial LVAD when compared to IABP, a device which has no mortality benefit when compared to medical therapy 2,3,4. Therefore, there is a large clinical need for a randomised controlled trial (RCT) comparing the routine use of intravascular microaxial LVAD vs IABP vs Medical therapy in AMI complicated by cardiogenic shock. Currently, there is one ongoing RCT titled DanGer Shock, which randomises patients to either intravascular microaxial LVAD or Guideline driven therapy and will assess mortality at 6 months. The study is due to be completed in January 2023.
Link to Article:
- Samsky, M.D., Morrow, D.A., Proudfoot, A.G., Hochman, J.S., Thiele, H. and Rao, S.V., 2021. Cardiogenic shock after acute myocardial infarction: a review. JAMA, 326(18), pp.1840-1850.
- Kim, Y., Shapero, K., Ahn, S.S., Goldsweig, A.M., Desai, N. and Altin, S.E., 2022. Outcomes of mechanical circulatory support for acute myocardial infarction complicated by cardiogenic shock. Catheterization and Cardiovascular Interventions, 99(3), pp.658-663.
- Dhruva, S.S., Ross, J.S., Mortazavi, B.J., Hurley, N.C., Krumholz, H.M., Curtis, J.P., Berkowitz, A., Masoudi, F.A., Messenger, J.C., Parzynski, C.S. and Ngufor, C., 2020. Association of use of an intravascular microaxial left ventricular assist device vs intra-aortic balloon pump with in-hospital mortality and major bleeding among patients with acute myocardial infarction complicated by cardiogenic shock. Jama, 323(8), pp.734-745.
- Thiele, H., Zeymer, U., Neumann, F.J., Ferenc, M., Olbrich, H.G., Hausleiter, J., Richardt, G., Hennersdorf, M., Empen, K., Fuernau, G. and Desch, S., 2012. Intraaortic balloon support for myocardial infarction with cardiogenic shock. New England Journal of Medicine, 367(14), pp.1287-1296.