Early Initiation of Impella Support Pre-PCI: Key to Consistent and Reproducible Outcome of Improved Survival in AMICS
Despite significant reduction in mortality in ST-segment elevation myocardial infarction (STEMI) following primary percutaneous coronary intervention (PCI), mortality rates in AMI complicated by cardiogenic shock (AMI-CGS) continues to be unacceptably high at about 50%.1
Percutaneous ventricular assist devices (pVADS) such as Impella® heart pumps have emerged as a promising therapeutic option for AMI-CGS, owing to its ability to maintain vital organ perfusion, prevent irreversible end-organ damage, and reduce workload of the heart.2 The superior hemodynamic benefits of Impella compared with intra-aortic balloon pump (IABP) have been demonstrated in patients with AMI-CGS in the ISAR-SHOCK trial.3 However, conduct of randomized trials assessing survival benefit with Impella use in AMI-CGS have been challenging given the multiple etiologies, heterogeneous clinical presentation, and variable rates of progression in patients with cardiogenic shock (CS).
Clinical evidence of the effectiveness of Impella devices in improving survival outcomes in AMI-CGS have been reported in multiple real-world studies, with all pointing to “early initiation of hemodynamic support with Impella prior to PCI” as the key component to achieve consistent and reproducible results. In fact, literature review of published real-world studies of Impella suggests that initiation of Impella support pre-PCI in AMI-CGS is associated with survival benefit during both short- and long-term follow-up and in critically-ill patients with unprotected left main coronary artery (ULMCA) as the culprit lesion.
Impella support pre-PCI is associated with survival benefit at short-term
Survival to Impella explantation
Recently, O’Neill et al. published the largest series of Impella use based on analysis of the Impella Quality (IQ) database including 15,259 patients with AMICS from 1,010 US hospitals.4 Survival to explantation was higher with use of Impella as first line treatment prior to PCI compared to use as salvage therapy after failure of therapy with inotropes or IABP (59% vs. 52%, p < 0.001). In addition, multivariate analysis revealed Impella use pre-PCI as an independent predictor of survival (OR 1.34, 95% CI 1.2-1.5, p < 0.0001).
Survival to discharge
The study by O’Neill et al. on 154 patients from the USpella registry was the first report to highlight improved survival in patients with AMI-CGS receiving Impella pre-PCI compared to post-PCI.5 Impella 2.5® device support was initiated pre-PCI in 63 patients and post-PCI in 91 patients. Baseline characteristics of the patients in both groups were similar although patients in the pre-PCI group had higher risk features including diabetes (56.7% vs. 36.4%, p = 0.02), peripheral vascular disease (PVD) (32.2% vs. 13.6%, p = 0.0008), chronic obstructive pulmonary disease (COPD) (22.9% vs. 10.7%, p = 0.05), and prior stroke (15.3% vs. 5.1%, p = 0.04). Patients in the pre-PCI group had more extensive revascularization with more lesions treated and more stents placed. Survival to discharge was higher in the pre-PCI group than the post-PCI group (65.1% vs. 40.7%, p = 0.003). Importantly, initiation of Impella 2.5 support prior to PCI was an independent predictor of survival in multivariate analysis (OR 0.37, 95% CI 0.17-0.79, p = 0.01).
Consistent results were observed in the report published based on analysis of 287 patients with AMI-CGS in the cVAD registry.6 Survival to discharge was higher in patients receiving Impella before PCI compared to those receiving Impella post-PCI (46% vs. 35%, p = 0.04). In addition, Impella implantation before PCI was independently associated with improved survival in multivariate analysis (OR 0.48, 95% CI 0.24-0.98, p = 0.04).
Joseph et al. analyzed 180 patients enrolled in the cVAD registry who underwent PCI and were supported with Impella for AMI-CGS.7 In this study, survival to discharge rates were higher in patients receiving Impella pre-PCI than post-PCI (57.3% vs. 35.2%, p = 0.003).
Flaherty et al. performed a meta-analysis of studies reporting in-hospital or 30-day mortality following Impella placement pre- vs. post-PCI in AMI-CGS.8 Three studies were identified including the above-mentioned study of 287 patients from the cVAD registry, an observational study of 68 patients by Schroeter et al., and the exploratory analysis of 24 patients in the IMPRESS in Severe Shock trial. The results of the pooled analysis of the 3 studies showed that early initiation of Impella prior to PCI decreased in-hospital/30-day by 48% compared to initiation of Impella post-PCI.
Survival to 1-year
Schroeter et al. performed retrospective analysis of long and short-term outcomes with Impella devices in 68 patients with AMI-CGS at the University of Goettingen heart center between 2009 and 2014.9 Patients included in this study were critically ill with 49% of them resuscitated following cardiac arrest. Impella support was initiated early during primary PCI in 59%. Early Impella initiation during PCI was associated with higher survival at 1-year than delayed use of Impella (43% vs. 13%, p = 0.04). In multivariate analysis, delayed initiation of Impella support was an independent predictor of mortality at 1-year (HR 2.15, 95% CI 1.02-4.63 p = 0.04).
Recently, Loehn et al published outcomes of Impella CP use in 73 patients with AMI-CGS from the Dresden Impella registry.10 Impella CP support was initiated pre-PCI in 34 patients and post-PCI in 39 patients. Survival at 1–year was higher in Impella pre-PCI group than post-PCI group (31.3% vs. 17.6%, p = 0.03). Further, multivariate analysis identified early initiation of Impella CP as an independent predictor of survival at discharge as well as at 30, 90 and 180 days.
Impella support pre-PCI of ULMCA culprit lesion is associated with survival benefit
Meraj et al. conducted an analysis of outcomes comparing initiation of Impella 2.5 support pre- versus post-PCI of ULMCA culprit lesion in 36 patients with AMI-CGS from the cVAD registry.11 Consistent with previous cVAD findings, Impella initiation prior to PCI of ULMCA was associated with higher survival to discharge (55% vs. 18.8%, p = 0.04) and 30-day survival (48.1% vs. 12.5%, p = 0.004) in this critically–ill patient population.
Consistent trend of higher survival with Impella use pre-PCI in sub-group analysis of randomized trials and cohort studies
In line with the consistent results of real-world studies, sub-group analysis of randomized trials in AMI-CGS show a trend of higher survival with Impella use pre-PCI.
Ouweneel et al. reported the results of an exploratory analysis of patients with cardiac arrest and severe shock complicating AMI treated with IABP (n=24) versus Impella CP (n=24) in the IMPRESS trial.12 Given that the trial was statistically underpowered, no difference in mortality was observed between Impella and IABP at 30 days and 6 months. In this trial, Impella or IABP support was initiated post revascularization in 83.3% (40/48). Of the 24 patients in the Impella group, support was initiated prior to PCI in 5 patients and post-PCI in 19 patients. Interestingly, survival at 30 days was 80% in the Impella pre-PCI group compared to 47% in the Impella post-PCI group.
Along the same lines, in the recent CULPRIT SHOCK trial13 investigating the outcomes of culprit only PCI versus immediate multivessel PCI in patients with AMICS, hemodynamic support with Impella was used in 81 patients. Of those, Impella support was initiated pre-PCI in 34 patients and post-PCI in 47 patients. Survival rate at 30 days was 41% in the pre-PCI group and 34% in the post-PCI group.
In the recent matched pair analysis of patients with AMI-CGS treated with Impella versus patients from the IABP-SHOCK II trial by Schrage et al.14 sub-group analysis evaluating timing of device implantation showed lower 30-day mortality with Impella use before PCI than the control group (42.7% vs. 53.3%, p = 0.18). Taken together, in the available literature of randomized trials and studies in AMI-CGS, sub-group analyses showed consistent trend of higher short-term survival with Impella use pre-PCI, further lending support to the findings of real-world studies.
The common theme of higher survival in AMI-CGS with Impella support pre-PCI in the growing body of clinical studies can be explained based on the results of experimental studies. Results from pre-clinical studies suggest that early initiation of LV unloading with Impella increases cardioprotective signaling thus improving cell survival and limiting myocardial damage.15, 16
The guiding principle with use of pVADs is ‘right patient, right time, and right device’. In the evidence base of Impella devices assessing timing of device implantation, there is no trial or study that has failed to demonstrate higher survival with earlier implantation before PCI. In essence, prompt use of Impella devices before PCI is the ‘right time’ for improving outcomes in AMI-CGS.
- Rab T, Ratanapo S, Kern KB, et al. Cardiac Shock Care Centers. JACC Review Topic of the Week. J Am Coll Cardiol 2018; 72:1972-80.
- Truesdell AG, Tehrani B, Singh R, et al. 'Combat' Approach to Cardiogenic Shock. Interv Cardiol. 2018;13(2):81-86.
- Seyfarth M, Sibbing D, Bauer I, et al. A Randomized Clinical Trial to Evaluate the Safety and Efficacy of a Percutaneous Left Ventricular Assist Device Versus Intra-Aortic Balloon Pumping for Treatment of Cardiogenic Shock Caused by Myocardial Infarction. J Am Coll Cardiol 2008; 52:1584–8.
- O'Neill WW, Grines C, Schreiber T, et al. Analysis of outcomes for 15,259 US patients with acute myocardial infarction cardiogenic shock (AMICS) supported with the Impella device. Am Heart J. 2018; 202:33-38.
- O'Neill WW, Schreiber T, Wohns DH, et al. The Current Use of Impella 2.5 in Acute Myocardial Infarction Complicated by Cardiogenic Shock: Results from the USpella Registry. J Intervent Cardiol. 2014; 27:1-11.
- 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; 119(6):845-851.
- Joseph SM, Brisco MA, Colvin M, et al. Women with cardiogenic shock derive greater benefit from early mechanical circulatory support: An update from the cVAD registry. J Interv Cardiol 2016; 29: 248–256.
- 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.
- 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; 28: 467–472.
- Loehn T, O’Neill WW, Lange B, et al. Long term survival after early unloading with Impella CP® in acute myocardial infarction complicated by cardiogenic shock. Eur Heart J Acute Cardiovasc Care 2018. Published ahead of print.
- Meraj PM, Doshi R, Schreiber T, et al. Impella 2.5 initiated prior to unprotected left main PCI in acute myocardial infarction complicated by cardiogenic shock improves early survival. J Intervent Cardiol 2017; 30: 256–263.
- 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.
- Thiele H, Akin I, Sandr M, et al. PCI Strategies in Patients with Acute Myocardial Infarction and Cardiogenic Shock. N Engl J Med 2017; 377:2419-2432.
- Schrage B, Ibrahim K, Loehn T, et al. Impella Support for Acute Myocardial Infarction complicated by Cardiogenic Shock: A Matched-Pair IABP-SHOCK II Trial 30-Day Mortality Analysis. Published ahead of print. Circulation 2018.
- Kapur NK, Qiao X, Paruchuri V, et al. Mechanical Pre-Conditioning With Acute Circulatory Support Before Reperfusion Limits Infarct Size in Acute Myocardial Infarction. JACC Heart Fail. 2015;3(11):873-882.
- Esposito ML, Zhang Y, Qiao X, et al. Left Ventricular Unloading Before Reperfusion Promotes Functional Recovery After Acute Myocardial Infarction. J Am Coll Cardiol. 2018;72(5):501–14.