Many patients with end-stage heart failure require mechanical circulatory support as a temporizing measure to enable multidisciplinary assessment for the most suitable therapeutic strategy. Impella 5.0 can be used as a bridge to decision to evaluate patients for potential recovery or bridge to next therapy (bridge to heart transplantation [BTHT] or bridge to durable left ventricular assist device or VAD [BLVAD]. Our goal was to examine single-center outcomes with the Impella 5.0 device as a bridge to next therapy (BTHT or BTLVAD). Forty patients underwent Impella 5.0 support from December 2009 to December 2015 with the intent of BTHT (n = 20) or BTLVAD (n = 20). The primary end point was survival to next therapy. Secondary end points included hemodynamic assessments and in-hospital/30-day complications. All patients were inotrope-dependent, with severely depressed left ventricular ejection fraction (12%) and renal insufficiency (creatinine 2.0 mg/dl). Most were Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS) 2 (66%) with biventricular failure (65%). Thirty patients (75%) survived to next therapy, including transplant (n = 13), durable LVAD (n = 15), and recovery of native heart function (n = 2). No strokes or major bleeding events requiring surgery were observed. Acute renal dysfunction, bleeding requiring transfusion, hemolysis, device malfunction, limb ischemia occurred in 13 (33%), 11 (28%), 3 (8%), 4 (10%), and 1 (3%) patients, respectively. Survival rate to discharge and/or 30 days was 68% (27 of 40). Temporary support with the Impella 5.0 allows for an effective bridge to decision strategy for hemodynamic stabilization and multidisciplinary heart team assessment of critically ill patients with heart failure. In conclusion, many of these patients can be subsequently bridged to the next therapy with favorable outcomes.
The use of temporary mechanical circulatory support has become a necessary component in the therapeutic armamentarium of cardiogenic shock refractory to conventional therapies. This measure promotes hemodynamic stabilization, enables end-organ recovery, and may facilitate more definitive therapies such as surgical revascularization, durable left ventricular assist device (LVAD) implantation, or even cardiac transplantation. The Impella 5.0 catheter (Abiomed, Danvers, Massachusetts) is a microaxial LVAD that can be inserted through the femoral or axillary artery through a surgical cut down and positioned in the left ventricle across the aortic valve under imaging guidance. The pump can yield complete hemodynamic support by delivering up to 5 L/minute of flow in the aorta while directly unloading the LV chamber. A number of case series have reported the use of the Impella device in acutely stabilizing patients in hemodynamic extremis after myocardial infarction. A few isolated case reports have also suggested the Impella may serve as an effective adjunct to select appropriate candidates that may benefit from LVAD alone, or improve candidacy of questionable patients exhibiting some degree of right ventricular dysfunction. However, the use of this device as a bridge to transplant or durable LVAD support remains largely uncharacterized. The objective of the present study was to examine potential hemodynamic benefits and outcomes of the Impella 5.0/LD device as a temporizing method for mechanical circulatory support in patients with end-stage heart failure undergoing multidisciplinary evaluation and assessment for durable replacement therapies.
Methods
Ninety consecutive patients who were supported with Impella technology (Abiomed) from March 2009 to December 2015 at a single center. Of these, 50 patients were excluded from the final analysis for the following reasons: 31 patients were supported with Impella 2.5, 6 patients were supported with Impella CP (cardiac power), 3 patients were supported with Impella RP (right peripheral), and 9 patients were supported with Impella 5.0 but with the intent to bridge the patient to recovery and failure to implant Impella occurred in 1 patient. These were all excluded because they were not implanted with intention toward advanced replacement therapies, either because they had predisposing contraindications or, in the case of the lower levels of support, Impella 2.5, or CP, were not in cardiogenic shock and were merely supported for high-risk percutaneous coronary intervention. The remaining 40 patients were supported with Impella 5.0 with the intent to bridge them to heart transplantation (BTHT, n = 20) or to bridge them to long-term mechanical circulatory support with a durable implantable LVAD (BLVAD, n = 20).
The Impella 5.0 is mounted on a 9Fr catheter shaft and the pump itself is 21Fr in diameter. Insertion is through cutdown onto the femoral artery and advanced retrograde under fluoroscopic guidance across the aortic valve into the LV. Insertion through the right axillary artery through a vascular graft is also performed under fluoroscopic or transesophageal echocardiography guidance and also allows for early mobilization of the patient. All 90 patients considered for this study were (85) or will be (5) enrolled in the Global cVAD (catheter based VAD) registry. The protocol of the registry was reviewed and approved by our institutional review board. Information was collected on patient demographics, hemodynamics, in-hospital complications, hospital discharge status, and 30-day follow-up. Stroke was defined as an ischemic or hemorrhagic cerebrovascular accident that persisted beyond 24 hours or <24 hours associated with infarction on an imaging study. Renal insufficiency was defined as abnormal kidney function requiring dialysis in patients who did not require dialysis before implant or an increase in serum creatinine of >2.5 mg/dl or >2 times baseline. Bleeding was defined as blood loss requiring blood transfusion or surgical exploration for resolution. Hemolysis was defined by abnormal plasma-free hemoglobin values >40 mg/dl or the presence of hematuria. Limb ischemia was reported whenever noted in the patient’s chart as new incidences of hypoperfusion of the leg requiring treatment and marked by such symptoms as decreased skin temperature of the limb or decreased peripheral pulses. Vascular complication without surgery included pseudoaneurysm, arteriovenous fistula, access-site thrombosis, and vessel dissection or perforation. Vascular complication requiring surgical repair was defined as a surgical intervention on a pseudoaneurysm, an arteriovenous fistula, a vessel dissection/perforation or an access-site thrombosis. Valve injury was defined as any injury to the aortic valve regardless of the cause as assessed by Doppler echocardiography, surgical exploration, or at autopsy. Right-sided cardiac failure was defined by echocardiographic parameters of right ventricular dysfunction such as very low tricuspid annular plane systolic excursion score, or severe dilatation with severe tricuspid regurgitation and/or by symptoms, and signs of persistent right ventricular dysfunction (central venous pressure >18 mm Hg with a cardiac index <2.0 L/min/m 2 in the absence of elevated left atrial/pulmonary capillary wedge pressure [>18 mm Hg]), tamponade, ventricular arrhythmias, or pneumothorax requiring either right VAD implantation or inotropic therapy.
The primary end point for this analysis was survival to next therapy (bridge to heart transplant or long-term LVAD). Secondary end points included the assessment of patients’ hemodynamics, in-hospital complications, and outcomes to discharge and 30-day postdischarge. Univariate analysis comparing patient supported for bridge to transplant versus bridge to an LVAD was performed with a chi-square test on discrete variables and with the Student t test or Wilcoxon rank-sum test for independent samples for continuous variables, as appropriate. All p values were 2-tailed and considered significant when p <0.05. Data analysis was performed using JMP version 10.0 (SAS Institute Inc, Cary, North Carolina).
Results
All 40 patients were supported with Impella 5.0 with the intent to bridge the patient to heart transplant or long-term LVAD. Twenty patients (50%) received the device as a BTHT decision and 20 patients received the device as a BTLVAD strategy to a durable LVAD ( Figure 1 ). Overall, the patients were predominantly INTERMACS score 1 (32%) or 2 (66%; Table 1 ). At presentation, all patients were inotrope dependent (100%), requiring an average of 2 inotropic agents for hemodynamic support. Other baseline characteristics included an LVEF of 12 ± 5%, a serum creatinine of 2.0 ± 0.8 g/dl, frequent concomitant right-sided cardiac failure (65%), and marginal cardiac output with elevated filling pressures ( Table 2 ). Baseline demographics, hemodynamic data, and extent of the end-organ dysfunction were comparable between the BTHT and BTLVAD groups ( Tables 1 and 2 ).
| Variable | All (N = 40) | Bridge to Heart Transplant (N = 20) | Bridge to LVAD (N = 20) | p value |
|---|---|---|---|---|
| Age (years) | 55±13 | 58±10 | 53±15 | 0.3 |
| Men | 78% | 80.0% | 75.0% | 1.0 |
| CAD | 43% | 50.0% | 35.5% | 0.5 |
| Diabetes | 41% | 50.0% | 31.6% | 0.3 |
| Hypertension | 38% | 35.0% | 40.0% | 1.0 |
| Inotrope dependent | 100% | 100.0% | 100.0% | 1.0 |
| Valvular heart disease | 26% | 30.0% | 22.2% | 0.7 |
| Arrhythmia | 72% | 70.0% | 73.7% | 1.0 |
| AICD/Pacemaker | 60% | 65.0% | 55.0% | 0.7 |
| Renal insufficiency | 71% | 84.2% | 57.9% | 0.2 |
| Liver insufficiency | 18% | 20.0% | 15.8% | 1.0 |
| Chronic obstructive pulmonary disease | 15% | 25.0% | 5.3% | 0.2 |
| Prior coronary bypass | 28% | 35.0% | 20.0% | 0.5 |
| Prior percutaneous coronary intervention | 23% | 25.0% | 20.0% | 1.0 |
| Cardiogenic shock on admission | 43% | 45.0% | 40.0% | 0.8 |
| Ischemic cardiomyopathy | 58% | 50.0% | 65.0% | 0.5 |
| NYHA Class IV | 95% | 90.0% | 100% | 0.5 |
| On heart transplant list prior to Impella | 48% | 95.0% | 0.0% | <.0001 |
| INTERMACS Score | ||||
| 1 | 32% (12/38) | 26% (5/19) | 37% (7/19) | 0.5 |
| 2 | 66% (25/38) | 68% (13/19) | 63% (12/19) | 0.7 |
| 3 | 3% (1/38) | 5% (1/19) | 0% (0/19) | 0.3 |
| Number of Inotropes prior to Impella | 1.8±0.9 | 1.9±1.2 | 1.8±0.6 | 0.7 |
| LVEF prior to Impella | 12±5 | 12±4 | 11±5 | 0.6 |
| Mechanical ventilation | 65.0% | 60.0% | 70.0% | 0.7 |
| Right heart failure ∗ | 25.0% | 18.2% | 33.3% | 0.6 |
| Duration of support (days) [range] | 7±5 [1 22] | 7±4 [2 16] | 8±6 [1 22] | 0.7 |
| Variable | All N = 40 | BTHT N = 20 | BTLVAD N = 20 | p value |
|---|---|---|---|---|
| Hemodynamics | ||||
| Heart rate (beats/min) | 103±22 | 104±17 | 101±27 | 0.7 |
| Systolic blood pressure (mmHg) | 89±16 | 87±15 | 91±17 | 0.4 |
| Diastolic blood pressure (mmHg) | 62±11 | 64±11 | 59±10 | 0.2 |
| Mean arterial blood pressure (mmHg) | 71±11 | 71±11 | 70±11 | 0.8 |
| Pulmonary artery diastolic blood pressure (mmHg) | 33±8 | 34±8 | 32±8 | 0.6 |
| Pulmonary capillary wedge pressure (mmHg) | 32±7 | 31±8 | 33±7 | 0.7 |
| Central venous pressure (mmHg) | 19±8 | 18±7 | 21±9 | 0.5 |
| Cardiac output (l/min) | 3.6±1.5 | 3.7±1.1 | 3.6±1.9 | 0.8 |
| Cardiac index (l/min/m 2 ) | 1.8±0.6 | 1.8±0.5 | 1.8±0.8 | 0.8 |
| Cardiac power output (Watts) | 0.5±0.2 | 0.5±0.2 | 0.6±0.3 | 0.3 |
| Laboratory Values | ||||
| Hemoglobin (g/dL) | 10.6±1.8 | 10.2± 1.7 | 10.1± 1.9 | 0.2 |
| Platelet count, (units/n/uL) | 209±114 | 192±66 | 227±149 | 0.4 |
| White blood cell count (units/n/uL) | 9.2±4.2 | 8.4±4.8 | 10.2±3.4 | 0.2 |
| Serum creatinine (mg/dL) | 2.0±0.8 | 2.0±0.8 | 2.0±0.7 | 0.7 |
| Total bilirubin (mg/dL) | 2.4±4.1 | 2.0±1.3 | 2.7±5.6 | 0.6 |
| Aspartate transaminase (units/L) | 98.0±177 | 89.1±190 | 105±172 | 0.8 |
| Alanine transaminase (units/L) | 89.3±141 | 87.4±133 | 90.9±152 | 0.9 |
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