Abstract
OBJECTIVES
The Impella 5.0 and 5.5 have largely superseded non-ambulatory temporary mechanical support devices; yet, clinical outcomes are predominantly limited to small series: this study presents the experience of a high-volume centre.
METHODS
An institutional clinical registry was used to identify all patients with cardiogenic shock who underwent Impella 5.0 or 5.5 implantation from January 2014 to March 2022. The primary outcome was survival to device explantation.
RESULTS
The study cohort comprised 221 patients, including 146 (66.1%) Impella 5.0 and 75 (33.9%) Impella 5.5 patients. The primary aetiology was non-ischaemic cardiomyopathy (50.7%, n = 112), ischaemic cardiomyopathy (23.1%, n = 51) and acute myocardial infarction (26.2%, n = 58). Patients were prospectively classified according to strategy as bridge to transplant (47.5%, n = 105), bridge to durable device (13.6%, n = 30) or bridge to recovery (38.9%, n = 86). Patients were predominantly Interagency Registry for Mechanically Assisted Circulatory Support profile 1 or 2 (95.0%, n = 210). The median bridging duration was 14 (range 0–137) days. Device exchange, Ischaemic stroke and ipsilateral arm ischaemia occurred in 8.1% (n = 18), 2.7% (n = 6) and 1.8% (n = 4) of patients, respectively. Compared to the 75 most recent Impella 5.0 patients, Impella 5.5 patients (n = 75) had lower rates of device exchange (4.0%, n = 3 vs 13.3%, n = 10, P = 0.04). Overall, 70.1% (n = 155) of patients survived to Impella explantation.
CONCLUSIONS
The Impella 5.0 and 5.5 provide safe and effective temporary mechanical support in appropriately selected patients with cardiogenic shock. The newer device generation may have a lower requirement for device exchange as compared to its predecessor.
Keywords: Heart transplant, mechanical circulatory support, heart failure
US and European consensus guidelines recommend the consideration of short-term mechanical circulatory support devices to improve end-organ perfusion in patients with cardiogenic shock despite optimal medical therapy [1, 2].
Graphical Abstract
INTRODUCTION
US and European consensus guidelines recommend the consideration of short-term mechanical circulatory support devices to improve end-organ perfusion in patients with cardiogenic shock despite optimal medical therapy [1, 2]. However, limited evidence regarding the balance between haemodynamic improvements and adverse events contributes to uncertainty regarding the wider application of these support systems.
The Impella 5.0 and Impella 5.5 (Abiomed, Danvers, MA, USA) are surgically placed transaortic microaxial left ventricular assist devices that unload the left ventricle and support haemodynamics in patients with cardiogenic shock, potentially delivering in excess of 5 l/min of forward flow. The Impella 5.0 received CE (conformité européenne) mark approval for up to 10 days of support in 2005, and the Impella 5.5 was approved for an extended 30 days of support in 2018. Proponents of these systems note that implantation of the Impella using an axillary artery approach allows ambulation during support [3]. Consequentially, the use of these catheter-based devices has largely superseded non-ambulatory mechanical circulatory support in some centres [4, 5]; yet, clinical outcomes are predominantly limited to small series [6, 7].
This study presents a single, high-volume centre’s entire experience with the Impella 5.0 and 5.5 devices.
MATERIALS AND METHODS
Ethical statement
This study was approved by the institutional review board of Cedars-Sinai Medical Center on 5 December 2019 (protocol number: STUDY00000332), approval included a waiver of informed consent.
Patients
A prospectively maintained institutional registry was used to retrospectively identify all consecutive patients who underwent surgically placed Impella 5.0 or 5.5 implantation for cardiogenic shock refractory to medical management from January 2014 through March 2022. All patients were assessed for device candidacy by a multidisciplinary team including cardiac surgeons, cardiologists, intensivists and social workers. Patients were prospectively classified according to intended bridging strategy as bridge to transplantation (BTT), bridge to implantation of a durable mechanical device (BTDD) or bridge to recovery (BTR) without the expectation of further surgical intervention. Patients who were initially too unwell for an accurate assessment of bridging destination and were implanted as ‘bridge to decision’ were classified according to the earliest consensus decision reached for planned bridging strategy. The decision to transition a patient to transplantation or a durable mechanical device is undertaken as a team approach and requires approval by our multidisciplinary selection committee. In patients with pre-existing mechanical circulatory support, the Impella 5.0 or 5.5 was placed as a primary left ventricular assist device or to wean patients from extracorporeal membrane oxygenation. The study cohort therefore comprises patients who underwent Impella 5.0 or 5.5 implantation as bridging therapy. Post-discharge follow-up was performed by the review of institutional electronic medical records and censored at patients last interaction with our health system.
Patient characteristics, bridging strategy and post-implantation outcomes were compared among patients supported by the Impella 5.0 and 5.5. The study cohort represents our institution’s entire experience with this family of devices. Subsequentially, all Impella 5.5 patients (n = 75) were compared with the 75 most recent Impella 5.0 patients to avoid comparisons being confounded by our institution’s learning curve with these devices or changes in management that occurred over this time period.
Study end points
The primary study end point was survival to device explantation for bridging destination: transplantation, durable device placement or recovery. Secondary end points comprised overall survival, improvement in haemodynamic data (central venous pressure, cardiac index and mean pulmonary artery pressure) upon Impella implantation and device-related complications, including implantation site bleeding requiring return to the operating room, device failure requiring device exchange, limb ischaemia, haemolysis, new-onset renal failure requiring dialysis or stroke during device support or within 24 h of explantation. Haemolysis was assessed among patients without additional mechanical circulatory support (for example extracorporeal membrane oxygenation) and was identified upon chart review where haemolysis was recorded as clinically significant by the respective provider. Peak lactate dehydrogenase and plasma free haemoglobin levels during device support are also provided as objective markers of haemolysis. Central venous pressure, cardiac index and mean pulmonary artery pressure were also assessed among patients without additional mechanical circulatory support.
Statistical analysis
Continuous variables were not normally distributed and are presented as medians with interquartile ranges (IQRs), categorical variables are presented as proportions with percentages. Variables with missing values are presented as proportions with their true denominator for categorical variables and marked as unknown for continuous variables. Between-group comparisons were performed using the Kruskal–Wallis test for continuous variables and the chi-squared test or Fisher’s exact test for categorical variables as appropriate. Haemodynamic data before and after device implantation was compared using the Wilcoxon signed-rank test. Mid-term survival was analysed by Kaplan–Meier methods and compared between groups using the log-rank test.
A P-value of <0.05 was considered statistically significant, and all tests were two-tailed. Analyses were carried out using SAS version 9.4 (SAS Institute, Cary, NC, USA).
RESULTS
Study population
The study cohort comprised 221 patients, including 146 (66.1%) Impella 5.0 and 75 (33.9%) Impella 5.5 patients. Baseline characteristics stratified by device generation are provided in Table 1. The median age of the entire study population was 58 (IQR 48–66) years and 86.0% (n = 190) were male. The primary indication for device placement was nonischemic cardiomyopathy (50.7%, n = 112), ischaemic cardiomyopathy (23.1%, n = 51) or cardiogenic shock status post myocardial infarction (26.2%, n = 58). The median pre-implantation left ventricular ejection fraction was 15% (IQR 11–20) and patients were predominantly Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS) score 1 (48.4%, n = 107) or 2 (46.6%, n = 103). The patients’ pre-implantation liver function tests and international normalized ratio are provided in Supplementary Material, Table S1. Overall, 50.2% (n = 111) were supported with another mechanical circulatory support device pre-implantation: 26.2% (n = 58) had an Impella CP in situ, 21.7% (n = 48) had an intra-aortic balloon pump in situ and 14.0% (n = 31) were receiving extracorporeal membrane oxygenation. The median time period from Impella CP, intra-aortic balloon pump and extracorporeal membrane oxygenation initiation to Impella 5.0 or 5.5 implantation was 4 (IQR 1–6) days, 3 (IQR 2–7) days and 6 (IQR 2–9) days, respectively.
Table 1:
Baseline patient characteristics stratified by mechanical circulatory support device generation
| All (n = 221) | Impella 5.0a (n = 75) | Impella 5.5 (n = 75) | P-Value | |
|---|---|---|---|---|
| Age at implant (years), median (IQR) | 58 (48–66) | 57 (43–66) | 59 (49–67) | 0.39 |
| Male sex, n (%) | 190 (86.0) | 62 (82.7) | 69 (92.0) | 0.14 |
| Height (cm), median (IQR) | 175 (168–181) | 174 (168–180) | 178 (170–183) | 0.26 |
| Weight (kg), median (IQR) | 82 (72–97) | 83 (73–99) | 86 (75–98) | 0.71 |
| Race, n (%) | 0.61 | |||
| White | 95 (43.0) | 29 (38.7) | 29 (38.7) | |
| Black | 41 (18.6) | 11 (14.7) | 16 (21.3) | |
| Hispanic | 38 (17.2) | 14 (18.7) | 16 (21.3) | |
| Asian | 25 (11.3) | 10 (13.3) | 7 (9.3) | |
| Other | 11 (5.0) | 5 (6.7) | 5 (6.7) | |
| Unknown | 11 (5.0) | 6 (8.0) | 2 (2.7) | |
| Primary diagnosis, n (%) | 0.40 | |||
| Nonischemic cardiomyopathy | 112 (50.7) | 42 (56.0) | 34 (45.3) | |
| Ischaemic cardiomyopathy | 51 (23.1) | 14 (18.7) | 19 (25.3) | |
| Cardiogenic shock post-Mycardial Infarction | 58 (26.2) | 19 (25.3) | 22 (29.3) | |
| Diabetes mellitus, n (%) | 102 (46.2) | 35 (46.7) | 36 (48.0) | 0.87 |
| Hypertension, n (%) | 155 (70.1) | 48 (64.0) | 62 (82.7) | 0.01 |
| Chronic Obstructive Pulmonary Disease, n (%) | 21 (9.5) | 2 (2.7) | 13 (17.3) | <0.01 |
| Cerebrovascular disease, n (%) | 19 (8.6) | 6 (8.0) | 6 (8.0) | 1.00 |
| Aortic valve disease, n (%) | ||||
| Aortic regurgitation ≥ moderate | 18 (8.1) | 11 (14.7) | 4 (5.3) | 0.10 |
| Aortic stenosis ≥ moderate | 5 (2.3) | 3 (4.0) | 2 (2.7) | 1.00 |
| Arrhythmia, n (%) | 146 (66.1) | 59 (78.7) | 49 (65.3) | 0.07 |
| Pre-implant creatinine (mg/dl), median (IQR) | 1.7 (1.2–2.4) | 1.5 (1.2–2.4) | 1.7 (1.0–2.5) | 0.47 |
| Pre-implant dialysis, n (%) | 37 (16.7) | 12 (16.0) | 14 (18.7) | 0.67 |
| Left ventricular ejection fractionb (%), median (IQR) | 15 (11–20) | 15 (10–20) | 15 (11–20) | 0.95 |
| INTERMACS profile, n (%) | 0.62 | |||
| 1 | 107 (48.4) | 33 (44.0) | 28 (37.3) | |
| 2 | 103 (46.6) | 37 (49.3) | 43 (57.3) | |
| 3 | 11 (5.0) | 5 (6.7) | 4 (5.3) | |
| Pre-implant IABP in situ, n (%) | 48 (21.7) | 16 (21.3) | 17 (22.7) | 0.84 |
| Pre-implant ECMO support, n (%) | 31 (14.0) | 5 (6.7) | 12 (16.0) | 0.12 |
| Pre-implant Impella CP in situ, n (%) | 58 (26.2) | 19 (25.3) | 19 (25.2) | 1.00 |
The most recent 75 cases of Impella 5.0.
Left ventricular ejection fraction missing in 1 patient.
ECMO: extracorporeal membrane oxygenation; IABP: intra-aortic balloon pump; INTERMACS: Interagency Registry for Mechanically Assisted Circulatory Support; IQR: interquartile range.
Bridging strategy
Patients underwent device implantation with an intent to BTT (47.5%, n = 105), BTDD (13.6%, n = 30) or BTR (38.9%, n = 86). The median total duration of bridging support was 14 (IQR 7–26) days for BTT, 12 (IQR 6–22) days for BTDD and 8 (IQR 4–14) days for BTR. Total duration of support among all groups ranged from a minimum of 0 to a maximum of 137 days.
Among those patients supported with a pre-existing mechanical circulatory support device, 92.7% (n = 127) of the pre-existing devices were removed upon Impella implantation: the Impella CP and intra-aortic balloon pump were removed for all patients and extracorporeal membrane oxygenation was discontinued for 67.7% (n = 21) patients. A further 19.5% (n = 6) of patients supported with pre-existing extracorporeal membrane oxygenation were weaned from this prior to Impella explantation. In 2 patients, extracorporeal membrane oxygenation was discontinued upon Impella implantation and subsequently reinitiated: 1 patient had venoarterial extracorporeal membrane oxygenation changed to venovenous extracorporeal membrane oxygenation the same day and the other had venoarterial extracorporeal membrane oxygenation restarted after 2 days. Overall, concomitant extracorporeal membrane oxygenation was required in 10.0% (n = 22) patients (including the 10 patients for whom the pre-impella extracorporeal membrane oxygentation was not discontinued), a concomitant right ventricular assist device was required in 9.0% (n = 20) patients and a right ventricular assist device with an oxygenator was required in 0.5% (n = 1) patients during Impella bridging. The extracorporeal membrane oxygenation cannulation was venoarterial in 90.9% (n = 20) patients and venovenous in 9.1% (n = 2) patients. The right ventricular assist device was a TandemHeart device with a Protek Duo cannula (CardiacAssist, Pittsburgh, PA, USA) in 85.7% (n = 18) patients and an Impella RP in 14.3% (n = 3) patients. None of the patients supported with a concomitant right ventricular assist device were able to have this weaned and explanted prior to Impella explantation.
Bridging outcomes
Implantation of the Impella 5.0 and 5.5 was associated with an improvement in haemodynamic data: median central venous pressure decreased from 11 (IQR 7–16) to 8 (IQR 5–12) mmHg (Fig. 1A), median cardiac index increased from 2.1 (IQR 1.8–2.5) to 2.7 (2.2–3.2) l/min/m2 (Fig. 1B) and median mean pulmonary artery pressure decreased from 33 (IQR 25–40) to 27 (IQR 24–32) mmHg (Fig. 1C) (all P < 0.01).
Figure 1:
Haemodynamic data collected pre-implantation and post-implantation of the Impella: (A) central venous pressure; (B) cardiac index; and (C) mean pulmonary artery pressure.
Among patients without concomitant circulatory support (n = 175), clinically significant haemolysis occurred in 24.6% (n = 43) of patients. The median peak lactate dehydrogenase was 1100 (IQR 639–1666) U/l and the median peak plasma free hemoglobin was 70 (IQR 45–120) mg/dl.
Overall, 52.4% (n = 118) of patients were extubated and 22.5% (n = 52) of patients were ambulatory within 24 hours of Impella implantation. Device exchange in the operative room was required in 8.1% (n = 18) patients: device malfunction in 9 patients, haemolysis in 3 patients, relocation from femoral to axilla in 4 patients and device malposition in 2 patients. Limb ischaemia in the ipsilateral arm to the surgically placed Impella occurred in 1.8% (n = 4) patients: all patients underwent an axillary thrombectomy and did not require further intervention. Additional complications included ischaemic stroke (2.7%, n = 6), bleeding requiring return to the operating room (7.7%, n = 17) and new-onset renal failure requiring dialysis (36.6%, n = 49). In total, 75.6% (n = 167) of patients survived to their respective bridging destinations and 91.0% (n = 152) of these survived to discharge. The overall in-hospital survival rate was 68.8% (n = 152). A concomitant kidney transplant was performed in 27.7% (n = 26) of patients who underwent heart transplantation. Among patients with pre-implant renal failure requiring dialysis that did not go on to receive a kidney transplant, 24.1% (n = 7) were able to discontinue dialysis following Impella implantation after a median of 18 (IQR 7–21) days. Bridging outcomes improved over the study period: survival to device explant in the first, second and third tercile of patients implanted was 65.8% (n = 48), 82.4% (n = 61) and 78.4% (n = 58), respectively (P = 0.05). Compared to patients with an isolated Impella device, those with concomitant circulatory support were less likely to survive to device explant (41.5%, n = 17 vs 83.3%, n = 150; P < 0.01) (Supplementary Material, Table S2). Among patients who did not survive to Impella explant, the causes of death were multi-system organ failure (66.7%, n = 36), sepsis (11.1%, n = 6), intracranial haemorrhage (11.1%, n = 6), ischaemic colitis (3.7%, n = 2), coronavirus disease 2019 (1.9%, n = 1), ischaemic stroke (1.9%, n = 1), anoxic brain injury (1.9%, n = 1) and lower limb ischaemia related to previous femoral Impella CP placement (1.9%, n = 1).
The median follow-up was 4 (IQR 1–25) months. Survival at 90 days post-implantation was 80.9% [95% confidence interval (CI) 73.4–88.4], 52.2% (95% CI 34.0–70.3) and 50.7% (95% CI 39.2–62.2) in the BTT, BTDD and BTR patients, respectively. Survival at 1 year post-implantation was 72.9% (95% CI 64.0–81.8), 46.7% (95% CI 28.8–64.5) and 39.1% (95% CI 27.6–50.7) in the BTT, BTDD and BTR patients, respectively (Fig. 2).
Figure 2:
Survival up to 1-year following Impella 5.0 or Impella 5.5 implantation, stratified by bridging strategy.
Impella device generation
Patients who underwent implantation of the Impella 5.5 (n = 75) were compared to the 75 most recent patients who underwent implantation of the Impella 5.0. The 2 groups were of similar age, sex, primary diagnosis and left ventricular ejection fraction (Table 1). Compared to Impella 5.0 patients, those undergoing Impella 5.5 implantation were numerically less likely to be INTERMACS profile 1 (37.3%, n = 28 vs 44.0%, n = 33; P = 0.41), but numerically more likely to be supported by extracorporeal membrane oxygenation at the time of implantation (16.0%, n = 12 vs 6.7%, n = 5; P = 0.12). Impella 5.5 patients were less likely to require device exchange (4.0%, n = 3 vs 13.3%, n = 10, P = 0.04) than Impella 5.0 patients. In patients with isolated Impella support (n = 128), Impella 5.5 patients also had numerically lower rates of haemolysis (22.6%, n = 14 vs 30.3%, n = 20; P = 0.32) and lower peak lactate dehydrogenase levels (median 765 vs 1312, P < 0.01). Other end points were similar between the 2 groups (Table 2).
Table 2:
Patient bridging strategy and outcomes stratified by mechanical circulatory support device generation
| All (n = 221) | Impella 5.0a (n = 75) | Impella 5.5 (n = 75) | P-Value | |
|---|---|---|---|---|
| Bridging strategy, n (%) | 0.11 | |||
| Bridge to transplant | 105 (47.5) | 38 (50.7) | 37 (49.3) | |
| Bridge to durable device | 30 (13.6) | 11 (14.7) | 4 (5.3) | |
| Bridge to recovery | 86 (38.9) | 26 (34.7) | 34 (45.3) | |
| Concomitant ECMO or right ventricular assist device, n (%) | 41 (18.6) | 9 (12.0) | 13 (17.3) | 0.36 |
| Bridging duration (days), median (IQR) | 11 (6–20) | 12 (6–20) | 11 (6–23) | 0.97 |
| Successful bridging, n (%) | 155 (70.1) | 60 (80.0) | 61 (81.3) | 0.84 |
| Extubated within 24 h of Impella implantation, n (%) | 118 (53.4) | 43 (57.3) | 40 (53.3) | 0.62 |
| Ambulatory within 24 h of Impella implantation, n (%) | 42 (23.5) | 20 (26.7) | 13 (17.3) | 0.17 |
| Device exchange, n (%) | 18 (8.1) | 10 (13.3) | 3 (4.0) | 0.04 |
| Haemolysis,bn (%) | 46/180 (25.6) | 20/66 (30.3) | 14/62 (22.6) | 0.18 |
| Peak lactate dehydrogenaseb,c (U/l), median (IQR) | 1100 (639–1666) | 1312 (922–1994) | 765 (457–1219) | <0.001 |
| Peak plasma free haemoglobinb,d (mg/dl), median (IQR) | 70 (45–120) | 70 (50–140) | 70 (40–120) | 0.27 |
| New renal failure requiring dialysis, n (%) | 49 (22.2) | 14 (18.7) | 18 (24.0) | 0.43 |
| Bleeding requiring return to OR, n (%) | 17 (7.7) | 6 (8.0) | 8 (10.7) | 0.57 |
| Ischaemic stroke, n (%) | 6 (2.7) | 2 (2.7) | 2 (2.7) | 1.00 |
| Limb ischaemia, n (%) | 4 (1.8) | 0 (0) | 1 (1.3) | 1.00 |
| Survival to discharge, n (%) | 152 (68.8) | 54 (72.0) | 58 (77.3) | 0.45 |
| Length of stay (days), median (IQR) | 28 (19–46) | 29 (21–44) | 27 (16–46) | 0.31 |
| 30-Day survival (%) (95% CI) | 72.9 (66.9–78.9) | 76.9 (67.2–86.5) | 77.6 (68.0–87.3) | 0.94 |
The most recent 75 cases of Impella 5.0.
Haemolysis during Impella support was assessed among patients without additional short-term mechanical circulatory support.
Peak lactate dehydrogenase was missing in 22 patients.
Peak plasma free hemoglobin was missing in 36 patients.
CI: confidence interval; ECMO: extracorporeal membrane oxygenation; IQR: interquartile range; OR: operating room.
DISCUSSION
This report details the outcomes of over 200 patients with refractory cardiogenic shock that were bridged with the Impella 5.0 or 5.5 devices at a single, high-volume centre. The study cohort represents a high acuity population, as individuals were predominantly INTERMACS class 1 or 2 and ∼50% were upgraded from pre-existing mechanical circulatory support. Outcomes were similar among patients implanted with the Impella 5.0 and 5.5: both devices offer low rates of adverse effects and reasonable bridging outcomes in this high-risk patient population.
The rates of survival to device explant in retrospective studies of patients who underwent Impella 5.0 or 5.5 implantation have varied widely from 41% to 79%, including our own previous report of up to 79% success when bridging to transplant [8–17]. In the present study, 75.6% of patients survived to their respective bridging destinations and 72.9% of patients were alive at 30 days following implant, demonstrating outcomes that continue to be acceptable with continual improvement in all bridging types. The differing baseline characteristics, device indications and bridging strategies of retrospective series make comparisons of outcomes difficult between these studies. We postulate that the relative success of our bridging outcomes is driven primarily by careful patient selection and an extensive experience with this support modality. Notably, post-transplant survival at 90 days was 80.9% for patients bridged to heart transplantation; yet, this was 52.2% for those bridged to a durable device—lower than has been reported in other series [14]. We suspect this to be a reflection of the high rate of transplantation in our cohort, as only 14% of patients underwent durable device implantation. Our institution benefits from a high regional heart donor availability, and our preferred destination therapy is heart transplantation wherever possible. Selection bias is therefore likely driving the disparate outcomes between bridging strategies.
Fewer than 3% of patients experienced an ischaemic stroke during bridging support or within 24 h of device explant at our institution. Several factors may have helped influence this relatively low stroke rate: For patients bridged to transplant, we utilize a standardized technique to remove the Impella device. This includes applying the cross-clamp high on the ascending aorta and across the driveline of the Impella, followed by the creation of a low aortotomy and division of the driveline just proximal to the pump itself. After this, the driveline can be removed from the axillary insertion site and the pump removed with the explanted heart. This technique avoids dragging the pump across the head vessels and may reduce embolic stroke risk. In addition, it is our policy to maintain the use of heparin in the purge solution whenever possible, even in the setting of non-life-threatening bleeding. This continual use of purge heparin may have helped to reduce the embolic stroke rate in this cohort.
The presence of an institutional learning curve for introduction of surgically placed Impella devices is evidenced by an improvement in the rate of survival to explantation from 65.8% for the first third of patients that underwent implantation to 80.4% for the most recent two-thirds. To optimize the survival of patients with cardiogenic shock refractory to medical management, accurate assessment of the underlying physiology remains essential. In this regard, we follow a previously published algorithm that relies on the use of echocardiography and pulmonary artery catheter to differentiate between different patterns of cardiogenic shock and guide appropriate therapy selection [8]. More importantly, all patients implanted with an Impella 5.0 or 5.5 at our institution undergo a multidisciplinary evaluation for heart transplantation or durable mechanical circulatory support either before device insertion or immediately afterward. This strategy is in line with recent studies that have reported improved outcomes in cardiogenic shock with standardized team-based care [18, 19]. Other studies have recently attempted to delineate factors independently associated with mortality among patients undergoing microaxial pump implantation, including high baseline serum lactate, high baseline MELD-XI score and prolonged mechanical ventilation. These predictors may aid in the identification of patients with cardiogenic shock that are most likely to benefit from implantation of the Impella, particularly for institutions that are introducing the device into practice [13, 20].
Comparison of outcomes between patients supported with the Impella 5.0 and newer-generation Impella 5.5 in this series revealed no difference in terms of the primary end point of survival to intended bridge strategy. In addition, no difference was found regarding ultimate discharge survival between the 2 device groups. However, patients supported with Impella 5.5 were less likely to require device exchange, and incidence of haemolysis as evidenced by peak lactate dehydrogenase levels was lower in the Impella 5.5 group. While both devices are microaxial pumps based on a very similar platform, incremental changes between the Impella 5.5 and Impella 5.0 including removal of the pigtail and improved device maneuverability and ease of positioning within the left ventricular outflow tract may help to mitigate the risk of haemolysis secondary to device malposition [21–23]. While significant haemolysis can result in severe renal injury with associated morbidity and mortality, the lack of survival difference between the 2 device groups seen here does not, in itself, justify the increase in cost from the older to newer device generation. However, other improvements, including ease of placement and maneuverability, are more difficult to quantify in terms of value. Furthermore, longer-term and more comprehensive data, as well as a critical examination of use trends, are clearly warranted.
Limitations
This observational study is subject to several limitations. The results of our single, high-volume centre experience may not be generalizable to all centres. Comparisons between the outcomes of patients who underwent Impella 5.0 and 5.5 implantation are not adjusted for confounders and may be subject to selection bias, although this is limited by the abrupt transition in use from 1 generation to the other. The use of a more recent cohort of patients who underwent Impella 5.0 implantation also omitted our institution’s learning curve with surgically placed Impella devices from the comparative analysis. Despite the use of a prospectively maintained institutional registry, additional variables were collected by retrospective chart review and some variables were subject to missing data.
CONCLUSION
The Impella 5.0 and 5.5 surgically placed temporary left ventricular assist devices provide safe and effective temporary mechanical support in appropriately selected patients with cardiogenic shock and facilitate bridging to transplant, device or recovery. The newest-generation Impella device (5.5) may have a favourable risk profile as compared to its predecessor (5.0), with lower requirements for device exchange; yet, the clinical significance of these findings is unclear.
Supplementary Material
ACKNOWLEDGEMENTS
The authors would like to thank Sharmini Premananthan and Aasha Krishnan for their role in data collection.
Glossary
ABBREVIATIONS
- BTDD
Bridge to implantation of a durable mechanical device
- BTR
Bridge to recovery
- BTT
Bridge to transplantation
- CI
Confidence interval
- INTERMACS
Interagency Registry for Mechanically Assisted Circulatory Support
- IQRs
Interquartile ranges
Contributor Information
George Gill, Department of Cardiac Surgery, Cedars-Sinai Medica Center, Los Angeles, CA, USA.
Georgina Rowe, Department of Cardiac Surgery, Cedars-Sinai Medica Center, Los Angeles, CA, USA.
Qiudong Chen, Department of Cardiac Surgery, Cedars-Sinai Medica Center, Los Angeles, CA, USA.
Jad Malas, Department of Cardiac Surgery, Cedars-Sinai Medica Center, Los Angeles, CA, USA.
Jason Thomas, Department of Cardiac Surgery, Cedars-Sinai Medica Center, Los Angeles, CA, USA.
Achille Peiris, Department of Cardiac Surgery, Cedars-Sinai Medica Center, Los Angeles, CA, USA.
Robert Cole, Department of Cardiology, Cedars-Sinai Medica Center, Los Angeles, CA, USA.
Joanna Chikwe, Department of Cardiac Surgery, Cedars-Sinai Medica Center, Los Angeles, CA, USA.
Dominick Megna, Department of Cardiac Surgery, Cedars-Sinai Medica Center, Los Angeles, CA, USA.
Dominic Emerson, Department of Cardiac Surgery, Cedars-Sinai Medica Center, Los Angeles, CA, USA.
SUPPLEMENTARY MATERIAL
Supplementary material is available at EJCTS online.
Funding
Qiudong Chen is supported by a grant from the National Institutes of Health for advanced heart disease research (grant number T32HL116273).
Conflict of interest: Dr Dominic Emerson has received honoraria from Abiomed. All other authors have no conflicts of interest to disclose.
DATA AVAILABILITY
The data underlying this article cannot be shared publicly for the privacy of individuals that participated in the study. The data will be shared on reasonable request to the corresponding author.
Author contributions
George Gill: Conceptualization; Data curation; Formal analysis; Investigation; Methodology; Writing—original draft; Writing—review & editing. Georgina Rowe: Conceptualization; Data curation; Formal analysis; Investigation; Methodology; Writing—original draft; Writing—review & editing. Qiudong Chen: Data curation; Formal analysis; Investigation; Methodology; Writing—original draft; Writing—review & editing. Jad Malas: Data curation; Investigation; Methodology; Writing—original draft; Writing—review & editing. Jason Thomas: Data curation; Formal analysis; Investigation; Methodology; Writing—review & editing. Achille Peiris: Data curation; Formal analysis; Investigation; Project administration; Writing—review & editing. Robert Cole: Conceptualization; Data curation; Methodology; Resources; Supervision; Writing—review & editing. Joanna Chikwe: Conceptualization; Investigation; Methodology; Resources; Supervision; Writing—review & editing. Dominick Megna: Conceptualization; Investigation; Methodology; Supervision; Writing– review & editing. Dominic Emerson: Conceptualization; Data curation; Investigation; Methodology; Resources; Supervision; Writing—original draft; Writing—review & editing.
Reviewer information
European Journal of Cardio-Thoracic Surgery thanks Hrvoje Gasparovic, David Spielvogel and the other, anonymous reviewer(s) for their contribution to the peer review process of this article.
Presented at the 36th European Association for Cardio-Thoracic Surgery Annual Meeting; Milan, Italy; October, 2022.
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The data underlying this article cannot be shared publicly for the privacy of individuals that participated in the study. The data will be shared on reasonable request to the corresponding author.