Commentary

Mechanical Circulatory Support in Percutaneous Coronary Interventions: Expanding the Possibilities

Harsh Agrawal, MD and Kul Aggarwal, MD

Harsh Agrawal, MD and Kul Aggarwal, MD

In this issue of the Journal of Invasive Cardiology, Anyanwu et al1 have described a series of patients with continuous flow ventricular assist devices (VADs) undergoing percutaneous coronary intervention (PCI). Interestingly, the indications for PCI in this series of patients were right ventricular (RV) failure, ventricular tachycardia (VT) storm, or hope of improving left ventricular (LV) function in a previously non-revascularized left anterior descending coronary artery. They have demonstrated feasibility and safety of the PCI procedure itself in this series. The use of anticoagulation for the VAD and the subsequent addition of dual-antiplatelet therapy after PCI is associated with increased risk of bleeding complications. Non-pulsatile flow is associated with increased risk of thrombosis. With increasing use of VADs, more patients will likely need PCI procedures while on these devices.

Although the PCI procedures were performed in patients with preexisting VADs in the above-mentioned series by Anyanwu and colleagues,1 the use of mechanical circulatory support for the purposes of supporting high-risk PCI is being increasingly utilized in the United States. The feasibility and usage of complex high-risk PCI are also increasing. This is especially true since the introduction of percutaneous VADs. The Society for Cardiac Angiography and Interventions (SCAI)/American College of Cardiology (ACC)/Heart Failure Society of America (HFSA)/Society of Thoracic Surgeons (STS) expert consensus document on the utilization of mechanical circulatory support (MCS) provides useful guidance on this subject.2

High-risk PCI is variously defined in the literature and may include patient characteristics, lesion characteristics, and hemodynamics. PCI to the left main or to an artery supplying a large amount of myocardium, severe LV dysfunction, or last remaining vessel or bypass graft would be some examples. Acute ST-elevation myocardial infarction (STEMI) with cardiogenic shock (CS) and/or serious hemodynamically significant ventricular arrhythmias is also a high-risk procedure. Severe peripheral vascular disease, renal failure, severe coronary calcification, tortuosity, and bifurcation lesions are some other factors.

Intraaortic balloon pump (IABP) was one of the first MCS devices to be used for coronary revascularization in patients with CS. Since then, several other percutaneous ventricular assist devices (PVADs) have been developed, such as Impella (Abiomed, Inc), TandemHeart (CardiacAssist, Inc), and extracorporeal membrane oxygenation (ECMO). 

Between July 2009 and June 2011, a total of 1,249,547 PCIs were performed in the United States. Of these, 17% were emergent cases.3 The ACC/American Heart Association (AHA)/SCAI guidelines support the use of these devices in various settings, eg, bridge to recovery in CS, as an adjunct to high-risk PCI, and in acute myocardial infarction (AMI) complicated by CS.2,4,5 There is still a clinical equipoise in regard to the reduction in hard clinical endpoints when using these devices.6 In this context, it would be useful to discuss the contemporary evidence regarding the use of MCS in the current PCI era. 

Intraaortic balloon pump (IABP). IABPs have historically been the most widely used MCS in patients undergoing PCI with hemodynamic instability and CS. The IABP works with the concept of diastolic augmentation of coronary perfusion by balloon inflation during diastole and reducing afterload. In the landmark SHOCK trial,7 a total of 302 patients who had LV dysfunction due to myocardial infarction were randomly assigned to revascularization with IABP support when needed versus medical stabilization. Six-month mortality was significantly better in the revascularization arm. Post hoc analysis of the SHOCK trial did show improved mortality in patients undergoing revascularization with IABP support.8 The IABP-SHOCK II trial9 was an open-label randomized trial of 600 patients with AMI complicated by CS, in a 1:1 fashion to revascularization with or without IABP support. Primary endpoint was all-cause 30-day mortality, which was similar in both groups (39.7% and 41.3%, respectively). Higher bleeding and stroke risk have also been reported with the use of IABP.10 Multiple meta-analyses have echoed the finding of the above trial and the registries.10,11 

Based on the results of these trials, the ACC/AHA/SCAI have given the use of IABP a class IIb (level of evidence C) recommendation, to be used in selected high-risk patients.4 The European Society of Cardiology (ESC)/European Association for Cardiothoracic Surgery (EACTS) have a class IIIA (harm) recommendation for the routine use of IABP in CS.12 

Percutaneous ventricular assist devices. Use of PVADs has been steadily increasing in the United States.13 From 2007-2011, a 1511% increase has been observed in the use of these devices.14 PVADs are capable of providing substantially greater hemodynamic support compared with IABP, thus improving the cardiac output, increasing mean arterial pressures, and lowering wedge pressure. Used in similar settings as an IABP, the PVAD currently holds a class IIb indication for use in patients with refractory CS and class IIb for elective insertion in carefully selected high-risk patients.4,5 National Inpatient Sample (NIS) data analysis from 2008-2012 of all patients undergoing PCI revealed that use of PVAD was associated with decreased mortality (9.9% vs 15.1%; odds ratio, 0.62; 95% CI, 0.55-0.71; P<.001) and complications (24.8% vs 31.5%; odds ratio, 0.72; 95% CI, 0.65-0.79; P<.001) in the propensity analysis as compared with IABP.13 In a recent meta-analysis by Romeo et al,15 which included 6 randomized control trials and 24 observational studies totaling 15,799 patients comparing IABP, PVADs, and medical therapy in AMI with CS, found that IABP was associated with increased mortality by 32.28% when compared with medical therapy alone. ECMO and IABP were associated with mortality benefit when used together instead of being used as stand-alone therapy.15 

Impella. The Impella is a pigtail-shaped device that is placed directly in the LV cavity. Of the 1322 patients in the United States Impella registry, a total of 637 patients underwent high-risk PCI with Impella 2.5; the authors noted that the mortality was on par with the clinical trials (2.8%), with no increase in complication rates and a significant decline in transfusion rates.16 The ISAR-SHOCK17 trial prospectively randomized patients with AMI and CS to either Impella-LP 2.5 or IABP; the change in cardiac index was significantly higher in the Impella group than in patients with IABP with no difference in 30-day mortality. The PROTECT II study6 compared Impella with other therapies, but was stopped early due to futility after 69% of the patients were enrolled because no differences were observed in major adverse events or mortality in either arm at 30-day follow-up. 

TandemHeart. In a randomized trial of TandemHeart vs IABP, in 41 patients with AMI and CS, use of PVAD was associated with improved cardiac output, pulmonary artery wedge pressure, cardiac power index, and reduced lactate levels.18 The PVAD group had more complications; however, there was no difference in mortality in either group. Burkhoff et al19 randomized 42 patients with CS, 70% of whom had AMI, to TandemHeart vs IABP. Although there was no significant survival benefit, TandemHeart was associated with improved hemodynamic parameters. The Mayo Clinic reported a 30-day survival of 90% in 54 patients undergoing high-risk PCI with TandemHeart support.20 

ECMO. In general patients with CS, ventricular assist ECMO provides augmentation in cardiac output, decreases preload, and increases mean arterial pressure and oxygenation; however, it may also cause an increase in afterload and myocardial oxygen demand, worsening ischemia and congestion. Sheu et al21 prospectively treated patients with STEMI and CS with either IABP support or IABP plus ECMO support. Patients who received IABP plus ECMO support had a survival benefit (72.0% vs 39.1%; P=.008), which translated to a relative risk reduction of 45.8%. In a retrospective single-center study in patients with AMI and CS, a total of 25 patients were on IABP support and 33 were on IABP plus ECMO support. Patients with IABP plus ECMO had improved survival (P=.001).22

Right heart support devices. RV failure is associated with increase mortality and morbidity. RV failure can decrease LV preload and diastolic filling and is associated with similar mortality as in patients with LV failure.23 About 50% of patients presenting with inferior MI can have echocardiographic evidence of RV dysfunction.23 Up to 40% of patients with LV failure can develop RV failure.24 Temporary MCS options such as TandemHeart RVAD, the Impella RP device, and VA-ECMO are now available for RV support. In the largest registry with 46 patients with centrifugal RVAD, patients with AMI had the best survival rates (33%).25 In the RECOVER-RIGHT26 trial, in 12 AMI patients out of a total 30 patients with refractory RV failure, 30-day survival was 73% with Impella RP support. 

Temporary VADs requiring median sternotomy. The BVS 5000 (Abiomed), CentriMag (St. Jude Medical), and Thoratec PVADs (St. Jude Medical) can be used for left, right, or biventricular support depending on the patient’s need and hemodynamics. They all require surgical expertise for placement. These devices are not routinely utilized for supporting PCI.

Durable VADs including total artificial heart. Recent analysis of the INTERMACS registry, with 502 very sick AMI patients supported with durable VADs, showed significant survival benefit with 93% at 1 month, 77% at 1 year, and 70% at 2 years, and no increase in complications in the risk-adjusted analysis.27 

Anticoagulation and antiplatelet therapy. All patients with MCS inserted percutaneously should be anticoagulated because they can have high rates of thrombosis and embolic phenomenon as the blood circulates in an external circuit in many of these devices and pulsatility is missing in some. VAD implantation causes consumption of coagulation proteins, activation of the coagulation cascade, platelet activation, and loss of von Willebrand protein.28 Bleeding complications are common in LVAD patients and are a cause of increased mortality and morbidity.29 Triple therapy after PCI is generally initiated in such patients. No data are available in regard to the recommended duration or outcomes in such patients, so the decision should be made on a case-by-case basis.

Conclusion

VADs should be considered for use in patients undergoing high-risk PCI, with CS and biventricular failure. Patient selection is paramount for the use of these devices as each can be conformed to specific patient and clinical needs. Uncertainty still remains regarding the superiority, safety, and long-term outcomes of these devices. A heart team approach is recommended in making sound patient and device selection. 

Randomized clinical trials are difficult to conduct in this patient population. Major drawbacks of large-bore sheaths and bleeding complications will hopefully decrease as these support devices evolve. MCS devices allow performance of PCI in this very high-risk patient population that would otherwise have no revascularization options. Percutaneous insertion and management of these devices make them more attractive.

References

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17.    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;52:1584-1588.

18.    Thiele H, Sick P, Boudriot E, et al. Randomized comparison of intra-aortic balloon support with a percutaneous left ventricular assist device in patients with revascularized acute myocardial infarction complicated by cardiogenic shock. Eur Heart J. 2005;26:1276-1283.

19.    Burkhoff D, Cohen H, Brunckhorst C, O’Neill WW, TandemHeart Investigators Group. A randomized multicenter clinical study to evaluate the safety and efficacy of the TandemHeart percutaneous ventricular assist device versus conventional therapy with intraaortic balloon pumping for treatment of cardiogenic shock. Am Heart J. 2006;152:469.e1-469.e8.

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24.    Kapur NK, Jumean MF. Defining the role for percutaneous mechanical circulatory support devices for medically refractory heart failure. Curr Heart Fail Rep. 2013;10:177-184.

25.    Kapur NK, Paruchuri V, Jagannathan A, et al. Mechanical circulatory support for right ventricular failure. JACC Heart Fail. 2013;1:127-134.

26.    Anderson MB, Goldstein J, Milano C, et al. Benefits of a novel percutaneous ventricular assist device for right heart failure: the prospective RECOVER RIGHT study of the Impella RP device. J Heart Lung Transplant. 2015;34:1549-1560.

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28.    Matsubayashi H, Fastenau DR, McIntyre JA. Changes in platelet activation associated with left ventricular assist system placement. J Heart Lung Transplant. 2000;19:462-468.

29.    Wayangankar SA, Bangalore S, McCoy LA, et al. Temporal trends and outcomes of patients undergoing percutaneous coronary interventions for cardiogenic shock in the setting of acute myocardial infarction: a report from the CathPCI registry. JACC Cardiovasc Interv. 2016;9:341-351.


From the Division of Cardiology, Department of Internal Medicine, University of Missouri School of Medicine, and Harry S. Truman VA Medical Center, Columbia, Missouri.

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.

Address for correspondence: Kul Aggarwal, MD, FACC, Professor of Medicine, Director, Cardiac Catheterization Lab, Truman VA Medical Center, and Professor of Medicine, University of Missouri School of Medicine, One Hospital Drive, Columbia, MO 65212. Email: aggarwalk@health.missouri.edu

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