Complex High-Risk Indicated Percutaneous Coronary Intervention With Prophylactic Use of the Impella CP Ventricular Assist Device

Abstract

Objectives. Patients with complex coronary artery disease, concomitant cardiac disease, and multiple comorbidities are addressed as complex higher-risk indicated patients (CHIPs). Selecting a revascularization strategy in this population remains challenging. If coronary artery bypass grafting is deemed high risk or patients are considered inoperable, high-risk percutaneous coronary intervention (PCI) with the support of the Impella CP ventricular assist device (Abiomed) may be an attractive alternative. Methods. In this retrospective, multicenter study, we included consecutive patients undergoing Impella CP-facilitated complex high-risk PCI. All patients were discussed by the heart team and were declined for surgery. Additionally, periprocedural mechanical circulatory support was deemed necessary. We collected demographic, clinical, and procedural characteristics. Major adverse cardiac event (MACE) and mortality rates up to 30 days were evaluated. Results. A total of 27 patients (median age, 73 ± 9.7 years; 74.1% men) were included in our study. The median SYNTAX score was 32 (range, 8-57) and EuroSCORE was 7.25% (range, 1.33-49.66; ± 12.76%). Periprocedural hemodynamic instability was observed in 1 patient (3.7%). In-hospital combined with 30-day mortality was 7.4% (2/27). No repeat revascularization was necessary. MACE was observed in 10 patients (37.0%). Six patients (22.2%) had a major bleeding complication, of which 2 were related to Impella access site. Median Impella run time was 1.22 hours and there was no significant decrease in kidney function. Median admission time after PCI was 3 days (range, 1-23; ± 4.76). Conclusions. The Impella CP system showed good feasibility and provided adequate hemodynamic support during high-risk PCI in this CHIP population.

Keywords: Impella CP, high-risk PCI, complex high-risk PCI

Historically, patients with complex coronary artery disease (CAD), eg, left main coronary artery disease, 3-vessel ­disease, or ≥1 chronic total occlusions (CTOs) and significant comorbidities, pose a challenge regarding the optimal revascularization strategy. Current guidelines by the European Society of Cardiology advise to base the decision on several risk-stratification scores (SYNTAX I and II and EuroSCORE), commonly resulting in a surgical approach.^1-3 Those who are deemed high risk or inoperable for coronary artery bypass grafting (CABG) are frequently relegated to medical therapy, as percutaneous coronary intervention (PCI) is offered infrequently due to perceived technical limitations and periprocedural adverse events. However, the evolution of interventional techniques and tools may offer (complete) revascularization in this multi-morbid population where revascularization was previously impossible or inadvisable.⁴ A holistic approach is mandatory in these patients, who are often referred to as complex higher-risk indicated patients (CHIPs). CHIP risk assessment comprises 3 clinical components: coronary anatomy (location and complexity), comorbid conditions, and concomitant cardiac disease (structural or valvular disease, left ventricular dysfunction, and decompensated heart failure with low hemodynamic tolerance).⁵

Hemodynamics can temporarily worsen while performing extensive and technically demanding procedures in this subset of patients because of PCI-related prolonged and repetitive ischemia, reperfusion, and intrinsic hemodynamic intolerance. As a result, coronary hypoperfusion, hypotension, and even progression to cardiogenic shock and cardiac arrest may occur.^6,7 Mechanical percutaneous circulatory support (MCS) reduces left ventricular stroke work and myocardial oxygen demand while maintaining systemic and coronary perfusion to provide hemodynamic support during complex cardiac procedures, including high-risk PCI, and may improve short- and long-term outcomes.^7,8

The Impella 2.5 system has proven to be safe, feasible, and useful for hemodynamic support in high-risk PCI.^6,9-14 The latest Impella Cardiac Power (CP) device (Abiomed, Inc) was designed to provide a higher level of support, with blood flow up to 3.7 L/min.¹⁵

This study aims to evaluate the feasibility, safety, and adequacy of the Impella CP for mechanical circulatory support in elective CHIPs who are declined surgery and assumed to have hemodynamic intolerance.

Methods

A multicenter registry was compiled that included all consecutive CHIPs who were discussed by the heart team. Either surgery was declined or patients had a strong personal preference for percutaneous revascularization after shared decision making and received PCI supported by the Impella CP ventricular assist device. The registry was approved by the medical ethical committee at each participating center, and written informed consent was obtained from all patients.

The Impella CP is a temporary coaxial rotary blood pump that unloads the left ventricle by aspirating blood from the LV cavity and ejecting it directly into the ascending aorta.^15,16 The Impella CP pump was inserted into the femoral artery through a large-bore (14-Fr) sheath.

Patients were analyzed at baseline for age, sex, and medical history, including the presence of diabetes mellitus, history of smoking, hypertension, history of malignant disease, peripheral arterial disease (PAD), prior CABG, renal function, left ventricular ejection fraction (LVEF), coronary interventions prior to the index procedure, and cardiac surgery including valvular surgery. LVEF was defined as good or mildly impaired (≥35%) or severely impaired (<35%). Renal function was defined and staged as an estimated glomerular filtration rate (eGFR) of either ≥60 mL/min or <60 mL/min.¹⁷

Procedural characteristics were analyzed for target vessel, single or multivessel procedure, presence of a CTO, procedural success, time spent on Impella support, and the amount of flow provided. To assess coronary anatomy, the SYNTAX and SYNTAX 2 scores were calculated using the online SYNTAX score calculators (http://syntaxscore.org/calculator/start.htm) for all patients. If there was a CTO present, the J-CTO score was calculated.¹⁷ Furthermore, the EuroSCORE was calculated for all patients using the online calculator (http://www.euroscore.org).

Outcomes were analyzed regarding periprocedural, in-hospital, and 30-day mortality rates. Furthermore, patients were analyzed regarding time spent in the intensive care unit (ICU), length of hospital stay, and major adverse cardiovascular event (MACE) rate. MACE was defined as a composite of all-cause death, myocardial infarction, stroke or transient ischemic attack (TIA), major bleeding events according to the Bleeding Academic Research Consortium (BARC) criteria, repeat revascularization, need for cardiac surgery, limb ischemia, cardiopulmonary resuscitation, or acute renal insufficiency. In a patient with multiple MACEs, the worst outcome was scored.

Hemodynamic instability was defined as a systolic blood pressure of <90 mm Hg for ≥30 minutes or ventricular arrhythmia. Major bleeding events post procedure were defined according to the BARC criteria; events with a BARC ≥3 were considered significant and included in the analysis.¹⁸ Blood hemoglobin levels (mmol/L) and thrombocyte count (10⁶/L) before and after the procedure were also collected.

Statistical analysis. Variables were analyzed using a Kolmogorov-Smirnov test to assess normal distribution. If there was a normal distribution, a paired t test was performed to assess significance. If variables were not normally distributed, a Wilcoxon signed rank test was performed. A 2-tailed P-value <.05 was considered statistically significant. Data were analyzed using Graphpad software (Graphpad).

Results

Baseline characteristics. From March 2018 until December 2020, a total of 27 patients underwent a complex high-risk PCI and received concomitant hemodynamic support with the Impella CP assist device. Patients were either declined surgery by the heart team (26/27 patients [96.3%], of which 10 patients [37.0%] had a high mortality associated with open-heart surgery) or had a strong personal preference for PCI (1/27 patients [3.7%]). The majority of patients (20/27 [74.1%]) were male, with a median age of 73 years (range, 50-88; ± 9.7). A known history of coronary artery disease was present in 10/37 patients (37%), of which 3/27 (11.1%) had a previous CABG. Diabetes mellitus was present in 9/27 patients (33.2%), a history of smoking in 11/27 patients (37.0%), hypercholesterolemia in 11/27 patients (40.7%), hypertension in 16/27 patients (59.3%), a history of cancer in 2/27 patients (7.4%) and PAD in 6/27 patients (22.2%). The LVEF was impaired in 25/27 patients (92.6%), of which 19 patients (70.4%) even had an LVEF <35% (Table 1). Of the 8 patients with an LVEF ≥35%, 6 patients had an LVEF between 35% and 45%; the other 2 patients had an LVEF >55% and were considered inoperable by the heart team because of several severe comorbidities.

Coronary anatomy. The target vessel was the left main coronary artery in 18/27 patients (66.7%) and the left anterior descending (LAD) in 24/27 patients (88.9%). A multivessel PCI was performed in the majority of patients (22/27; 81.5%) and a single-vessel PCI of the right coronary artery (RCA) was performed in 3/27 patients (11.1%). There were no isolated left circumflex (LCX) artery lesions. A CTO was present in 20/27 patients (74.1%). The median J-CTO score was 2 (range, 0-4; ± 1.03) for a total of 26 CTO lesions. The median SYNTAX score was 32 (range, 8-57) and the median SYNTAX 2 score was 51.7 (range, 30.5-80.7) for PCI and 40.7 (range, 22.3-64.9) for CABG. The median EuroSCORE was 7.25% (range, 1.33-49.66; ± 12.76%) (Table 2).

Procedural characteristics and outcome. Hemodynamic instability was observed in 1 patient (3.7%). This patient experienced periods of nonpulsatility and, after removing the Impella device, remained hypotensive and received vasopressor agents for a short time after which the blood pressure recovered. The median Impella run time was 1.22 hours (range, 0.16-3.29; ± 0.71), with a median flow of 3.45 L/min (range, 2.8-3.7; ± 0.24). All patients were weaned from the Impella at the cardiac catheterization laboratory after PCI.

Successful revascularization of the target lesion(s) was achieved in all patients except 2 (7.4%). Of these, 1 patient had a nonsuccessful CTO-PCI of the RCA and the second patient had successful revascularization of the LAD and a CTO of the LCX. Because of the extent of the procedure, a CTO of the RCA was left untreated and needed no repeat revascularization because of the absence of angina.

A total of 24 bifurcation lesions in 23 patients were present. In 4 patients, no bifurcation lesion was present. In these 4 patients, ≥1 CTOs were present. In 3 patients (11.1%), plaque modification with rotational atherectomy was performed because of severe calcification. In 26 patients, a total of 102 drug-eluting stents were implanted with a total stent length of 3206 mm and a mean stent length per patient of 123 mm. In 1 patient, 4 drug-coated balloons and no stents were implanted because of multiple previous stent layers.

In all patients, closure of the Impella femoral access site was performed with a minimum of 2 Perclose Proglide suture systems (Abbott Vascular). Successful hemostasis was achieved in all patients at the catheterization laboratory. In 3 patients (11.1%), a visible hematoma was present. Femoral contrast extravasation was objectivated on angiography from the access site that was used for the PCI. In 1 of these patients, minimal blush was visible, for which a pressure bandage was placed. All other patients had no visible hematoma or bleeding from the access site.

In-hospital mortality was 7.4% (2/27 patients), as was mortality at 30 days. Both patients died several hours after the procedure. One patient died as a result of multiorgan failure after a postprocedural tamponade requiring pericardiocentesis. A review of the index angiogram showed an Ellis type II perforation in the mid-RCA. A second patient died in the intensive care unit as a result of multiorgan failure following cardiac arrest with pulseless electrical activity. The latter is the patient who experienced hemodynamic instability during PCI. This patient was initially accepted for revascularization by means of CABG. However, while on the waiting list, the patient experienced intestinal ischemia, a pulmonary and urinary tract infection, and progressive kidney injury, which increased the EuroSCORE from 2% to 25.9%. In combination with a decrease in mobility and obesity, the patient was declared inoperable by the surgeons. Because of repetitive decompensated heart failure with a low LVEF, the patient was accepted for high-risk PCI with support of an Impella device.

Periprocedural MACE was observed in 10 patients (37.0%) (Table 3). Among these are the 2 aforementioned patients who died as a result of tamponade and multiorgan failure. A third patient experienced a type 4A myocardial infarction and a fourth patient experienced repeated ventricular tachycardia that stabilized after medication. In the remaining 6 patients (22.2%), hemorrhagic complications (BARC ≥3) occurred. All patients had a femoral access-site related bleeding, of which 2 patients (7.4%) had significant bleeding from the Impella access site and needed acute vascular surgery to restore the defect. Of the remaining 4 patients (14.8%), 3 underwent a contrast computed tomography (CT), of which 2 patients had a hematoma on the non-Impella access site but no active bleeding, and the remaining patient did not receive a contrast CT. Each hemorrhagic complication was observed within a few hours after the procedure.

The mean hemoglobin levels were 7.7 mmol/L (range, 5.3-9.9; ± 1.2) prior to the procedure, which dropped significantly to 6.7 mmol/L (range, 5.2-8.6; ± 1.1) after the procedure (P<.01). There were no cases of limb ischemia. Activated clotting time (ACT) was maintained >250 seconds during all procedures.

Renal function declined after the procedure, but was not significantly different (P=.18). The mean thrombocyte count was 280.5 10⁶/L (range, 92-531; ± 116.3), which dropped to 243 10⁶/L (range, 110-493; ± 84.7) (P<.01).

Of all patients, 5/27 (18.5%) were transferred to the intensive care unit, where they stayed for 1 day each (range, 1-1; ± 1). Two patients were transported to the intensive care unit for observation after vascular surgery, which was necessary because of bleeding from the access site, 1 patient because of hemodynamic instability after tamponade, 1 patient after in-hospital cardiac arrest, and 1 patient for hemodynamic observation. Median admission time in the hospital after the procedure was 3 days (range, 1-23; ± 4.76) (Table 4).

Discussion

In this retrospective cohort, in which we evaluated 27 Impella CP-facilitated CHIPs, hemodynamic instability during the procedure was observed in only 1 patient (3.7%). This indicates the primary purpose of the Impella CP. In comparison, data from PROTECT II, a large randomized clinical trial comparing Impella with intra-aortic balloon pump, showed hypotension during support with the Impella 2.5 in 10.19%.¹² Furthermore, repeat revascularization was needed in 1.4% within 30 days in the PROTECT II data, whereas in our cohort 2 patients (7.4%) had incomplete revascularization but none of the patients needed repeat revascularization.

Mortality at 30 days was low (2/27 patients; 7.4%), with both fatalities occurring during hospitalization within a few hours after PCI. One patient died as a result of complications after cardiac tamponade, not directly related to the Impella implantation. The second patient died of multiorgan failure following cardiac arrest with pulseless electrical activity. Although the actual cause of the fatality remains unclear, it is speculated that it was related to the PCI procedure, given this is also the only patient who experienced hemodynamic instability during PCI. We hypothesized that myocardial stunning due to repetitive ischemia during PCI could be the cause of the fatality. In comparison with the PROTECT II data, which showed a mortality rate of 7.6% at 30 days in the Impella arm, our mortality rate shows similar outcomes.¹²

In our cohort, 6/27 patients (22.2%) had major bleeding complications (BARC ≥3) from 1 of the access sites, taking into consideration that the incidence of femoral bleeding complication as a result of the insertion of the Impella device was low (7.4%). The patients with an Impella-related bleeding, however, needed vascular surgery to treat the bleeding complication, whereas the other patients could be treated with blood transfusion only. In comparison, data from the PROTECT II and Europella registries demonstrated major bleeding complication rates of 12.5% and 6.2%, respectively. However, the percentage of Impella-related femoral bleeding complications from these studies is not known.^12,13 The Impella 2.5 device, which uses a 12-13 Fr cannula, was used in both studies, in comparison with the 14 Fr cannula used in the Impella CP in our cohort, which showed a higher bleeding complication rate.

The relatively high percentage of major bleeding complications in our cohort can be explained in various ways. First, the participating centers were low-volume, high-risk PCI centers with a small learning curve for Impella placement. A prespecified analysis in the PROTECT II trial by Henriques et al showed a significant reduction of major adverse events after 90 days in the learning curve for Impella placement.¹⁹ It is known that large-bore access procedures in general are related to a higher number of bleeding complications. In our cohort, the access-site complication rate was mainly observed in the non-Impella access site and therefore not Impella related.

Second, our cohort comprises CHIPs with multiple comorbidities and extensive vascular disease. In our cohort, 22.2% of the patients suffered from PAD, which could contribute to a higher bleeding rate from an access site. A Mayo Clinic study from 2004 showed a significantly greater occurrence of blood loss requiring transfusion in patients with PAD undergoing PCI in comparison with patients without PAD (11% vs 5.8%; P<.001).²⁰ In addition, a study by Jeremias et al showed a significantly greater incidence of MACE in patients with PAD than in patients without PAD (20.4% vs 7.0%; P<.001).²¹ In 3 patients (11.1%), effective hemostasis was confirmed by contralateral contrast injection post access-site closure. In these patients, no major bleeding occurred. It is known that contralateral contrast injection and/or ultrasound-guided puncture might be more optimal in patients treated with large-bore interventions and vascular calcified disease and might have produced a lower bleeding rate.²²

Third, all patients had successful hemostasis post procedure at the catheterization laboratory, whether confirmed by contralateral injection or macroscopic visualization. All bleeding complications were observed within a few hours after PCI and transferred to the cardiac care unit. It is therefore assumed that mechanical manipulation, either by intrinsic patient movement or patient-bed transferral and transport could be related to access-site bleeding complications.

Fourth, during large-bore catheter and Impella removal, the ACT was not objectivated. Commonly, hemostasis is achieved when the ACT drops to <180 seconds. Potentially, a higher ACT could have influenced the occurrence of hemorrhagic complications.

In conclusion, bleeding complications continue to be a ^­substantial source of morbidity, especially in patients undergoing large-bore access procedures. In addition to puncture management, closure management of the femoral access site is also of great importance. Different closure devices are available (eg, Perclose ProGlide, Prostar XL, Manta) and show good results in large-bore access procedures.^23-26 However, further research is needed to identify the ideal closure device.

In comparison with the bleeding complications, our study showed no cases of limb ischemia post procedure. A previous study that investigated vascular complications after Impella showed limb ischemia in 13.3%.²⁷

In our cohort, kidney function deteriorated slightly, but this worsening was not significant and could suggest that the higher hemodynamic support of the Impella CP might be renoprotective. This is in accordance with the previous Global cVAD Renal Protection study, which demonstrated that Impella 2.5 support could exert an acute kidney injury protective effect during high-risk PCI (4.9% vs 21.9%—a 77.6% risk decrease).²⁸

In our cohort, the Impella CP device could be removed in all patients at the catheterization laboratory. This is in contrast to the Impella 2.5 and intra-aortic balloon pump devices in the PROTECT II trial (5.9% vs 36.7%; P<.001).¹² In addition, longer support time post procedure was required for the intra-aortic balloon pump patients (P<.001).¹² It is accordingly speculated that the CP provides better hemodynamic support. Coronary perfusion and myocardial work expenditure may be addressed better, allowing swift weaning from the Impella, and thus allowing for more complete revascularization.²⁹ In our cohort, the median run time of Impella CP was 1.22 hours and this is comparable with data from PROTECT II (1.9 hours). Considering our cohort needed no repeat revascularization, this might suggest a shorter run time with more revascularization in a comparable high-risk PCI group. In comparison with other support devices, our cohort showed a lower run time.^30,31 This might be indicative of a shorter weaning time from Impella in comparison with other MCS devices.

Study limitations. A limitation of our study is the retrospective, multicenter, and observational design, with a relatively small cohort size. There was no uniform protocol for the procedure in terms of access-site puncture or closure. In comparison with another study on the Impella CP, this is to our knowledge the largest retrospective cohort on Impella CP-facilitated CHIPs in current literature.³² A future prospectively randomized controlled trial on different assist devices must determine which device is most appropriate in these complex high-risk patients.

Conclusion

The Impella CP provides adequate hemodynamic support during revascularization of CHIPs in whom circulatory assistance is deemed necessary. Impella CP shows good feasibility and fulfills its primary purpose of providing excellent hemodynamic support during prolonged and anatomical high-risk coronary interventions, with low Impella-related access-site bleeding and in-hospital mortality rates. Future properly designed trials are necessary to define the best MCS for complex high-risk PCI.

Affiliations and Disclosures

From the ¹Amsterdam Universitair Medisch Centrum, Vrije Universiteit Medisch Centrum, Amsterdam, The Netherlands; ²Leids Universitair Medisch Centrum, Leiden, The Netherlands; ³Medisch Centrum Leeuwarden, Leeuwarden, The Netherlands; and ⁴Ziekenhuis Netwerk Antwerpen Middelheim, Antwerpen, Belgium.

Disclosure: The authors have completed and returned the ICMJE Form for Disclosure of Potential Conflicts of Interest. The authors report no conflicts of interest regarding the content herein.

Manuscript accepted March 17, 2022.

Address for correspondence: Floris S. van den Brink, MD, PhD, Leids Universitair Medisch Centrum, Leiden, Zuid-Holland, 2333ZA, The Netherlands. Email: floris.s.van.den.brink@gmail.com

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