High-Risk PCI and Balloon Valvuloplasty in the Setting of ACS Complicated by Critical Aortic Stenosis Using Percutaneous Left Ventricular Assist Device

Acute myocardial infarction (AMI) carries a high mortality and morbidity. Timely intervention is critical for salvaging the myocardium and preventing any further mechanical complications. When accompanied by critical aortic stenosis, the outcomes are dismal. Percutaneous left ventricular assist devices (pLVAD) are increasingly used for high-risk percutaneous coronary interventions (PCI). We describe a unique case of AMI complicated by concomitant critical aortic stenosis where pLVAD was used for hemodynamic stabilization during PCI and valvuloplasty. 

Case

An 86-year-old female with past medical history of coronary artery disease with PCI to the proximal left anterior descending artery (LAD) and proximal circumflex artery (LCx) ten years prior, severe aortic stenosis, and chronic atrial fibrillation (on anticoagulation) presented with typical angina, dyspnea, and diaphoresis for four hours. Upon evaluation, she was pale, diaphoretic and in distress due to chest pain.  Her initial blood pressure was 179/90 mmHg, heart rate was 71 bpm, and pulse oximetry was 94% on room air. She had bibasilar crackles and grade 3/6 late peaking ejection systolic murmur at the left upper sternal border. A twelve-lead electrocardiogram revealed rate controlled atrial fibrillation with diffuse ST depressions across infero-lateral leads (Figure 1). A chest x-ray confirmed signs of congestive heart failure. Her hemoglobin was 11.8 g/dl, INR was 1.6, and initial troponin was 0.23 ng/ml. An emergent bedside echo revealed critical aortic stenosis (valve area = 0.5 cm2), moderate mitral regurgitation, and an ejection fraction of 30% with severe hypokinesis of the anterior and antero-septal wall (Figure 2). She was started on aspirin, heparin infusion, and intravenous morphine with temporary relief. The troponin peaked at 4.47 ng/ml and trended down. Coronary angiography revealed a 95% heavily calcified lesion in the mid segment of the left main (LM) coronary artery (Figure 3). There was haziness within this lesion, suggesting the presence of possible thrombus. The proximal LAD and LCx stents were patent, with 10-20% in-stent restenosis. The right coronary artery (RCA) was a dominant vessel with diffuse calcification throughout the artery. It had an 80% ostial lesion and 85% mid-distal RCA stenosis (Figure 3). The ilio-femoral artery had diffuse calcification without any significant stenosis. At this stage, cardiothoracic surgery was consulted for coronary artery bypass grafting and aortic valve replacement. The Society of Thoracic Surgery (STS) risk-adjusted mortality was calculated at 18%, which was deemed high risk. After extensive discussion with patient and family, she was taken to the cath lab for high-risk coronary intervention with possible aortic valvuloplasty for palliation of symptoms.     

Access was obtained in bilateral common femoral arteries (CFA) and right common femoral vein.  An .018-inch steel core wire was advanced into the left ventricle through the left CFA. An .035-inch Amplatz stiff wire (Boston Scientific) was placed in the left ventricle via the right CFA. An Impella CP pLVAD (Abiomed) was advanced into the left ventricle from the left CFA over the steel core wire using standard technique and maximal hemodynamic support was initiated. 

Using a 6 French (Fr) Judkins left (JL)-4 guide from the right CFA, the LM coronary artery was engaged. The LM lesion was crossed with an .014-inch, 180 cm Whisper wire (Abbott). Laser atherectomy was performed across the lesion with an 0.9 mm excimer laser coronary atherectomy (ELCA) catheter (Spectranetics). A total of 2 passes were undertaken at a fluency of 80 and at a rate of 80. The lesion was predilated with a 2.75 x 8 mm NC Quantum Apex balloon (Boston Scientific) and stented with a 4.0 x 12 mm Promus stent (Boston Scientific). Subsequent angiography revealed excellent stent apposition with improved flow in the distal vessels (Figure 4). 

The RCA ostium was engaged with a 6 Fr JR-4 guiding catheter. The proximal and mid to distal RCA lesions were crossed with an .014-inch, 180 cm Prowater wire (Abbott). The distal lesion was predilated with a 2.25 x 8 mm Apex balloon (Boston Scientific), and stented with 3.0 x 24 mm Promus stent using support from a 6 Fr Guidezilla guide extender (Boston Scientific). Stenting of the proximal RCA lesion was performed with a 4.0 x 12 mm Promus stent. Subsequent angiography revealed excellent stent apposition with brisk flow into the distal vessel (Figure 5). 

Balloon aortic valvuloplasty was accomplished with a 16 x 5 cm Z-Med balloon (Braun Interventional), advanced over the Amplatz wire (Figure 6). A total of 2 inflations were performed under rapid right ventricular pacing using a 5 Fr pacer wire placed via right femoral vein access. The balloon and Impella CP were removed. The patient tolerated the procedure well. The left CFA access site was closed with a previously placed Perclose ProGlide device (Abbott) using the pre-close technique. On the right CFA, the sheath was exchanged to a 12 cm, 12 Fr sheath and sutured in place for removal the next day. The patient was transferred to the coronary care unit in stable condition without any complications post procedure and discharged to a rehabilitation center in stable condition.  

Discussion

The advent of transcatheter aortic valve replacement (TAVR) has revolutionized the treatment of patients with symptomatic severe aortic stenosis who are not otherwise surgical candidates.¹ Patients with concomitant significant myocardial ischemia will need revascularization prior to undergoing percutaneous valvuloplasty or TAVR. Significant LM coronary artery stenosis usually identifies an anatomic subset requiring coronary artery bypass graft surgery (CABG) for revascularization. However, patients with LM coronary artery disease and severe left ventricular dysfunction are often poor surgical candidates, especially in those with severe co-morbidities. Consequently, PCI has emerged as an alternative to CABG in patients presenting with an unacceptably high mortality risk for cardiac surgery, even if these patients are still considered to be at very high risk for PCI-related mortality.² PCI in this subset of patients is high risk, can be challenging, and carries significant morbidity. If associated with depressed LV function, PCI may require adjunctive ventricular support, either intra-aortic balloon pump (IABP) or mechanical circulatory support (MCS) during the procedure. 

There are various pLVADs for high-risk PCI, the choice of which is dependent on operator experience, patient characteristics, ability to safely and effectively deliver the device, and cath lab capabilities. The pLVADs currently used in the United States are the intra-aortic balloon pump (IABP) (Maquet), TandemHeart (CardiacAssist), and Impella.

IABP remains one of the oldest, most familiar devices that can be rapidly deployed.³ It helps augment diastolic pressure, diminishes afterload and wall tension work, and thus reduces myocardial oxygen demand while increasing oxygen delivery, thereby favorably affecting ischemic threshold. However, the other MCS devices theoretically mitigate ischemia to a greater degree than an IABP. Also, for effective IABP functioning, the patient must have stable electric rhythm in order to achieve its full potential, a feature that may not be consistently present in the critically ill patient, as in our patient. An IABP also carries increased incidence of stroke, which is a major concern. Overcoming these shortfalls, the ideal MCS device would therefore maximally reduce oxygen consumption (demand) by reducing both stroke work and potential energy while simultaneously augmenting oxygen supply by increasing coronary blood flow. 

The TandemHeart is a percutaneous left atrial to iliac artery bypass which is powered by an external centrifugal pump that provides cardiac output of about 3.5 to 4 L/min of forward flow by standard implantation technique.⁴ There are isolated case reports of utility of Tandem Heart in critical aortic stenosis. The first patient described had cardiogenic shock secondary to critical valvular stenosis. Following TandemHeart placement, the hemodynamic and metabolic parameters improved dramatically.⁵ In a case report by Rajdev et al, the TandemHeart was used as a support device in a patient with severe AS and triple-vessel disease for percutaneous balloon aortic valvuloplasty and PCI simultaneously and successfully.⁶ The safety and feasibility of using TandemHeart for multiple high-risk percutaneous interventions in a single setting was successfully demonstrated. 

The Impella device provides forward systemic flow with unloading effect on the failing left ventricle.⁷ These hemodynamic benefits are paramount to the management of extremely ill patients. In contrast to other MCS devices (extracorporeal membrane oxygenation [ECMO] and TandemHeart), the Impella device has the advantage of being an easily implantable device. The Impella device can provide between 2.5 to 5 L/min of forward flow. These devices are approved by the FDA for temporal hemodynamic support. Since FDA approval, the Impella device utilization has been extended from “high-risk” PCI, cardiogenic shock, post-pericardiotomy syndrome, to ventricular tachycardia radiofrequency ablation procedures. In the PROTECT II randomized trial, IABP was compared to Impella 2.5 in patients undergoing high-risk PCI/un-protected LM and with reduced ejection fraction (EF) (<30-35%). Impella use was associated with better hemodynamic support, a trend towards decreased major adverse cardiac events (MACE) at 30 days (35.1 vs. 40.1%, P=.227) and a significant reduction in MACE at 90 days (40 vs. 51%, P=.023).⁸

In a single-center study of patients undergoing high-risk PCI under MCS, without concomitant severe valvular disease, angiographic success was high and major complication rates were low with MCS.⁹ In a national in-patient sample database analysis, trends in utility of various MCS devices were studied.¹⁰ It was found that the utilization of MCS (Impella and TandemHeart) increased from 1.3% of all PCIs in 2004 to 3.4% in 2012 (P<.001). On final analysis, unadjusted in-hospital mortality was lower in MCS devices compared with IABP recipients (12.8% vs 20.9%, P<.001). However, in propensity-matched analyses (1:2), in-hospital mortality was similar in both groups (odds ratio 0.88, 95% confidence interval 0.70 to 1.09).

Our 86-year-old patient was estimated to have a very high operative mortality risk associated with surgery (EuroSCORE II of 40.3%, STS risk score of 17%). The SYNTAX score was 20. Thus, the cumulative 4-year MACE rate was 28.6% with PCI and 28.1% with CABG. Given complex coronary anatomy, depressed left ventricular function, concomitant critical aortic stenosis, and with unprotected LM disease, the PCI risk was significantly high. This necessitated an assist device to accomplish successful PCI and to perform percutaneous balloon aortic valvuloplasty for symptom relief. Given the complexity of the procedure, a more durable peri-procedural hemodynamic support was necessary.

In a case report by Lonono et al, the Impella 2.5 was successfully used for hemodynamic support in percutaneous balloon aortic valvuloplasty in a high-risk patient.¹¹ In our patient, we decided to use Impella CP as the patient was undergoing complex, high-risk PCI and possible percutaneous balloon aortic valvuloplasty for symptom control. Impella CP is a version of the Impella 2.5 that can provide up to 4L/min of forward flow in acutely sick patients. The Impella maintains coronary blood flow in patients with tenuous hemodynamics, especially during balloon inflation or stent deployment. It allows for greater unloading of the left ventricle, thus decreasing left ventricular end-diastolic pressure and improving myocardial perfusion. The Impella helps by maintaining a stable arterial pressure throughout the procedure, thus assisting complete revascularization.

Given the depressed EF and wall motion abnormality, PCI was prudent to improve survival. In order to prevent any further afterload mismatch due to severe aortic stenosis, percutaneous balloon aortic valvuloplasty was necessary for palliative purposes until TAVR could be performed. Percutaneous aortic balloon valvuloplasty and arterial revascularization might improve the patient’s left ventricular systolic function and hemodynamic profile over a period of time, thus making this patient a possible TAVR candidate.¹²

In our case, the Impella CP helped by augmenting cardiac output and blood pressure, reducing cardiac workload, and decreasing pulmonary capillary wedge pressure and pulmonary arterial pressure.  In a study by Spiro et al, a series of 5 patients with profile similar to our patient were studied. In that series, the Impella 2.5 and Impella CP were found to be safe and efficacious, allowing lengthy, complex procedures with better outcomes. Our patient did not have any stroke or renal insufficiency in the peri-operative and post procedural setting, which supports the notion that the Impella device may improve systemic microcirculation in patients with acute coronary syndrome.¹³ In our patient, we were able to achieve complete revascularization and percutaneous aortic balloon vavuloplasty. Moreover, the patient tolerated the procedure well, with no MACE, or post-procedural renal or access site complications. This case demonstrates the safety and feasibility of using the Impella CP assist device for complex PCI and concomitant percutaneous aortic balloon valvuloplasty in a single setting. The patient eventually underwent TAVR 3 months after this procedure without any complications.

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Disclosures: Dr. Gajanana, Dr. Figueredo, Dr. Morris, Dr. Janzer, and Dr. Witke report no conflicts of interest regarding the content herein. Dr. George reports he is a consultant for Abbott, Atrium/Maquet, Boston Scientific, Edwards, and Medtronic.

The authors can be contacted via Dr. Jon George at jcgeorgemd@gmail.com.