Aetna considers a FDA-approved ventricular assist device (VAD) medically necessary for any of the following FDA-approved indications:

1. Members with post-cardiotomy ventricular dysfunction on maximum inotropic volume and support and intra-aortic balloon pump where indicated; or
   
2. As a bridge to transplant for members who are awaiting heart transplantation; or
   
3. As destination therapy for members with severe (NYHA Class IV) heart failure, and who are ineligible for heart transplantation due to age or co-morbidities.

Aetna considers VADs experimental and investigational for all other indications.

Aetna considers a FDA-approved percutaneous left ventricular assist device (LVAD) (e.g., the TandemHeart and the Impella Recover LP 2.5) medically necessary when individual meets any of the criteria stated above.

Aetna considers percutaneous LVADs experimental and investigational for all other indications (e.g., aortic aneurysm surgery and cardiogenic short not related to cardiac surgery).

Ventricular assist devices (VADs) fall into the general category of mechanical circulatory assist devices, which also includes cardiopulmonary bypass and intra-aortic balloon pumps.  There are several different types of VADs currently in use; the devices can be broadly subdivided into centrifugal or pulsatile pumps.  Centrifugal pumps operate on the principle of a cyclone.  Blood is diverted through cannulae placed in the right or left heart to an external chamber with a centrifugal pump.  Centrifugal pumps include the Biopump, the Sarns-3M and the Hemopump.

Pulsatile pumps are subdivided into pneumatic and electromechanical types.  Each type can be operated in several different modes including a synchronous mode triggered by the EKG (similar to an intra-aortic balloon pump) and an asynchronous mode.  Placement of the inflow and outflow cannulae is variable.  According to expert consensus, it is usually preferable to cannulate the left atrium because it is technically easier and spares the ventricle further injury.   However, flow rates are improved with ventricular cannulation and in patients awaiting transplant, injury to the myocardium is not a concern.  Pulsatile pumps include the Abiomed, Thoratec (Pierce Donachy), Novacor and HeartMate devices. 

There is a small subset of patents who experience reversible heart failure after open heart surgery despite maximal support with proper volume loading, drug therapy and an intra-aortic balloon pump.  The etiology of the heart failure in these patients is hypothesized to be related to "stunned" myocardium.  VADs have been used as a method of short-term support in these patients.   Several clinical studies have demonstrated that a substantial proportion of patients with post-cardiotomy cardiogenic shock can be successfully treated with a VAD, subsequently weaned from the device, and discharged home.

VADs have also been used as a bridge to transplant.  Several clinical studies have demonstrated the success of VADs in improving survival rates to heart transplantation.  In addition, VADs have been shown to significantly improve patients’ functional status prior to heart transplantation such that patients are  overall better surgical candidates.

The Federal Food and Drug Administration (FDA) has approved the HeartMate SNAP-VE Left Ventricular Assist System (LVAS) (Thoratec Corporation) as a long-term permanent implant (destination therapy) for end-stage heart failure patients who are not eligible for heart transplantation.  In addition to use as a bridge to transplant for cardiac transplant candidates, the FDA product labeling for the HeartMate states that the device is indicated for use in patients with NYHA Class IV end-stage left ventricular failure who have received optimal medical therapy for at least 60 of the last 90 days and who have a life expectancy of less than two years and who are not candidates for cardiac transplantation (e.g., old age, insulin-dependent diabetes with organ damage, chronic kidney dysfunction, or other factors, such as cancer, obesity, etc. that would eliminate heart transplantation as a treatment option).  The FDA approval was based on the results of the REMATCH trial, a multicenter randomized controlled clinical trial comparing permanent implantation of a HeartMate left ventricular assist device (LVAD) to maximum medical therapy in 129 adults with end-stage heart failure who because of their age or co-morbidities were not eligible for a heart transplant (Rose, et al., 2001).  To be eligible for study participation, patients had to have NYHA class IV heart failure for at least 90 days despite attempted therapy with an ACE inhibitor, diuretics, and digoxin; an ejection fraction less than or equal to 25 percent; and an exercise peak O2 uptake less than or equal to 12 mL per kilogram per minute or a continued need for intravenous inotropic therapy because of symptomatic hypotension, decreasing renal function, or worsening pulmonary congestion.  After 18 months of enrollment, entry criteria were relaxed to include patients with symptoms of NYHA class III or IV heart failure for 28 days and 14 days of support with an intra-aortic balloon pump or with a dependence on intravenous inotropic agents with 2 failed weaning attempts.   Survival was significantly improved from 25 percent at 1 year in the medical therapy group to 52 percent in the LVAD group (relative risk, 0.52 (95 percent confidence interval 0.34-0.78)).  Median length of survival for patients implanted with the HeartMate LVAD was 408 days compared to 108 days for patients in the medical therapy group.  However, only 23 percent of LVAD patients survived to two years (compared to 8 percent in the medical group) (p = 0.09), and serious adverse events were 2.35 times as frequent in the LVAD group, predominately caused by infection, bleeding, neurological dysfunction, and device malfunction.

The TandemHeart, a percutaneous transseptal ventricular assist (PTVA) device, is an external blood pump that provides temporary hemodynamic support to a weakened heart.  It is used for critically ill patients who have sustained a massive myocardial infarction or sudden heart failure and do not have enough blood flow to support their organs.  The TandemHeart augments left ventricular (LV) contractility, enhancing blood flow until the patient’s condition becomes more stable or the patient is strong enough to undergo an interventional procedure (e.g., angioplasty).  In potential heart transplant patients or patients awaiting a mechanical heart assist device, the TandemHeart is considered a "bridge" giving patients extra time for the weaken heart to rest.

Rajdev et al (2008) stated that patients with multi-vessel disease, left main coronary artery (LMCA) disease or left main equivalent and/or moderate-to-severe LV dysfunction with elevated LV end-diastolic pressure are at increased risk of complications during percutaneous coronary intervention (PCI).  The TandemHeart is a non-pulsatile PTVA that offers vital short-term circulatory support during high-risk PCI.  These invetigators assessed the feasibility and safety of implanting a prophylactic LVAD prior to high-risk PCI and evaluated the impact of suture-mediated pre-closure of the arteriotomy site on minimizing vascular complications.  Between April 2004 and November 2005, the TandemHeart was implanted in 20 patients undergoing high-risk PCI; 8 patients underwent unprotected LMCA stenting, and rotational atherectomy was used in 17 patients.  Suture-mediated femoral artery pre-closure was performed prior to inserting a large-bore arterial cannula.  The TandemHeart was successfully implanted in all 20 patients.  Mean LV ejection fraction of subjects was 38 +/- 18 %.  Time-to-implantation of the TandemHeart, duration of hemodynamic support, as well as mean flow of the TandemHeart device were 31 +/- 9 mins, 74 +/- 40 mins, and 2.5 +/- 1.3 L/min, respectively.  At the end of PCI, the TandemHeart was removed in all cases and sutures were deployed in 18/20 (90 %) patients. There was only 1 minor vascular complication, and the average length of stay was 2 +/- 1 days.  Peri-procedural and in-hospital mortality was 0 %.  The authors concluded that implantation of the Tandemheart PTVA device was safe and feasible in patients undergoing high-risk PCI with excellent hemodynamic support.  Application of suture-mediated devices prior to large arteriotomies can significantly reduce the incidence of vascular complications.

Vranckx and colleagues (2008) reported their 6-year experience with the TandemHeart.  Between September 2000 to July 2006, this device supported the circulation of 23 patients (mean age of 59 years, range of 46 to 74) who were admitted for high-risk (either emergency or elective) PCI.  Successful implantation was achieved in 100 % of patients.  The mean time for implementation of circulatory support was 35 mins (range of 16 to 62).  The index PCI was successful in all patients except 2.  A pump flow up to 4L/min was achieved with significant reduction of LV filling pressures, pulmonary capillary wedge pressure, and with significant increase of systemic arterial pressures.  Duration of support ranged from 1 to 222 hrs (mean of 31 +/- 49.8).  Five patients died with the TandemHeart in place, 4 of whom were in irreversible cardiogenic shock at admission.  Mild-to-moderate access site bleeding was seen in 27 % of patients.  One patient experienced a loge syndrome of the leg.  Core temperature (Ct) decreased to less than 36.5 degrees C in 6 patients, profound hypothermia (Ct less than 35 degrees C) was observed in 2 patients.  There was no technical device failure.  The authors concluded that the TandemHeart provides effective, total LV support in very high-risk PCI settings.  The rate of device-related cardiac and vascular complications was acceptable.

Al-Husami et al (2008) described their experience of patients, from December 2005 through May 2007 who underwent PCI with severely depressed LV systolic function and complex coronary lesions.  The complex coronary lesions included multiple vessel coronary artery disease, left main (LM) coronary artery disease, calcified coronary lesions and bypass graft disease.  All patients were clinically assessed to be at too high of a risk for circulatory collapse without maximal hemodynamic support while they underwent high-risk PCI.  The TandemHeart PTVA device may be able to provide the necessary circulatory support needed to enhance procedural success and patient safety during high-risk PCI.  These investigators implanted the TandemHeart PTVA device in 6 patients who underwent high-risk PCI.  There was unanimity among several physicians in the authors' institution that each patient was an exceptionally high-risk for circulatory collapse due to the anticipated procedural complexity.  The average ejection fraction was 33 % (range of 15 to 65 %); 5 of the patients were considered to be at an unacceptably high-risk for coronary artery bypass surgery.  All 6 patients underwent multi-vessel PCI -- 5 underwent unprotected LM PCI; 1 of the 5 underwent vein-graft PCI as well as a debulking procedure with rotational atherectomy and PCI of the LM.  These researchers had a 100 % success rate with implantation of the TandemHeart PTVA device.  Five of the 6 patients were alive at 30 days post-procedure.  One patient died 3 days after the procedure due to multi-organ failure.  A vascular surgeon performed the removal of the devices with no associated complications.  The authors concluded that these findings demonstrated that hemodynamic support could be achieved safely, efficiently and effectively by the TandemHeart PTVA device in anticipation of high-risk PCI.

The Impella Recover LP 2.5, a percutaneous LVAD, is an intra-vascular micro-axial blood pump designed for short-term circulatory support in conditions characterized by profoundly reduced ventricular function.  It provides up to 2.5 L/min forward flow from the LV  into the systemic circulation.  Vecchio and colleagues (2008) evaluated the feasibility, safety and efficacy of the Impella Recover LP 2.5 LVAD in patients with cardiogenic shock or undergoing high-risk PCI.  A total of 11 patients presenting cardiogenic shock (n = 6) or scheduled for high-risk percutaneous re-vascularization (n = 5) were evaluated.  The Impella pump was successfully implanted in all patients, except one.  When implanted, the device was correctly positioned in the LV and remained in a stable position.  Bleedings occurred in 7 patients (5 of them presented cardiogenic shock), while renal failure and severe thrombocytopenia were observed in 4 and 1 patients, respectively, all with cardiogenic shock.  During high-risk procedures, the Impella pump succeeded in obtaining hemodynamic stability, while in only 2 patients with cardiogenic shock the device determined a significant improvement of hemodynamic variables.  All elective patients and 2 patients with cardiogenic shock were discharged from the hospital and were still alive at 30-day follow-up.  The authors concluded that these data, although preliminary due to the limited sample size, demonstrated the feasibility, safety and efficacy of the Impella Recover LP 2.5 during high-risk PCIs, even though the benefits of prophylactic deployment of such a system have to be further investigated.  The use of Impella Recover LP 2.5 in patients with cardiogenic shock is feasible and safe, however it maybe insufficient in reversing an advanced cardiogenic shock which, probably, has to be treated with more powerful LVADs.

Lam and associates (2009) noted that circulatory support during PCI in patients with ST-element elevation myocardial infarction (STEMI) aims at maintaining hemodynamic stability and organ perfusion.  However, continuous flow pumps may interfere with the normal pulsatile circulation and the microcirculatory function.  Sidestream dark field (SDF) imaging allows the visualization of microvascular structure and function of tissue and may provide information regarding the efficacy of the circulatory support.  Sidestream dark field was used to study the sublingual microcirculation (MC) in 6 anterior STEMI patients treated with PCI; 3 patients received the Impella LP 2.5 device (Impella group) and 3 patients received no support (control group).  Microcirculation was assessed at baseline, at 24, 48 and 72 hrs after PCI.  Data were analyzed using a validated scoring method and the microvascular flow index (MFI) and perfused vessel density (PVD) were calculated.  Microcirculation of 3 healthy controls was used as normalized standard.  Normal MC depending on both functional capillary density (PVD) and flow velocity or quality (MFI), as observed in healthy controls, was only achieved in the Impella group and paralleled improvement in LV function.  Functional capillary density in the control and Impella groups were equal and above the level of healthy controls, respectively.  The quality of microcirculatory flow reached values of healthy controls only in the Impella group.  The authors concluded that MC assessed by SDF improved in STEMI patients treated with the Impella LP 2.5 device to levels observed in healthy persons and remained sub-optimal after 72 hrs in patients without support.

In a prospective, multi-center study, Dixon and associates (2009) assessed the safety and feasibility of the Impella 2.5 system in patients undergoing high-risk PCI.  A total of 20 patients who underwent high-risk PCI with minimally invasive circulatory support employing the Impella 2.5 system were included in this study.  All patients had poor LV function (ejection fraction less than or equal to 35 %) and underwent PCI on an unprotected LMCA or last patent coronary conduit.  Patients with recent ST-segment elevation myocardial infarction or cardiogenic shock were excluded.  The primary safety end point was the incidence of major adverse cardiac events at 30 days.  The primary efficacy end point was freedom from hemodynamic compromise during PCI (defined as a decrease in mean arterial pressure below 60 mmHg for greater than10 mins).  The Impella 2.5 device was implanted successfully in all patients.  The mean duration of circulatory support was 1.7 +/- 0.6 hrs (range of 0.4 to 2.5).  Mean pump flow during PCI was 2.2 +/- 0.3 L/min.  At 30 days, the incidence of major adverse cardiac events was 20 % (2 patients had a peri-procedural myocardial infarction; 2 patients died at days 12 and 14).  There was no evidence of aortic valve injury, cardiac perforation, or limb ischemia.  Two patients (10 %) developed mild, transient hemolysis without clinical sequelae.  None of the patients developed hemodynamic compromise during PCI.  The authors concluded that the Impella 2.5 system is safe, easy to implant, and provides excellent hemodynamic support during high-risk PCI.

Granfeldt et al (2009) reported the use of the Impella device at 3 cardiothoracic units in Sweden.  A total of 50 patients (35 men, mean age of 55.8 years, range of 26 to 84) underwent implantation of 26 ImpellaLP 2.5/5.0 (support-time 0.1 to 14 days), 16 ImpellaLD (support-time 1 to 7 days) and 8 ImpellaRD (support-time 0.1 to 8 days) between 2003 and 2007.  Implantation was performed because of post-cardiotomy heart failure (surgical group, n = 33) or for various states of heart failure in cardiological patients (non-surgical group, n = 17).  The intention for the treatments was mainly to use the pump as a "bridge-to-recovery".  Early mortality in the surgical and non-surgical groups was 45 % and 23 %, respectively.  Complications included infection, 36 % and right ventricular failure, 28 %.  Cardiac output and cardiac power output post-operatively were significantly higher among survivors than non-survivors.  The authors concluded that the Impella recovery axial-flow system facilitates treatment in acute heart failure.  Early intervention in patients with acute heart failure and optimized hemodynamics in the post-implantation period seem to be of importance for long-term survival.  Insufficient early response to therapy should urge to consider further treatment options.

Seyfarth and co-workers (2008) examined if the Impella LP 2.5 provides superior hemodynamic support compared with the intra-aortic balloon pump (IABP) for patients with cardiogenic shock (n = 26).  The primary end point was the change of the cardiac index (CI) from baseline to 30 mins after implantation.  Secondary end points included lactic acidosis, hemolysis, and mortality after 30 days.  In 25 patients, the allocated device (n = 13 for IABP, n = 12 for Impella LP 2.5) could be safely placed.  One patient died before implantation.  The CI after 30 mins of support was significantly increased in patients with the Impella LP 2.5 compared with patients with IABP (Impella: DeltaCI = 0.49 +/- 0.46 L/min/m(2); IABP: DeltaCI = 0.11 +/- 0.31 L/min/m(2); p = 0.02).  Overall 30-day mortality was 46 % in both groups.  The authors concluded that in patients presenting with cardiogenic shock caused by acute myocardial infarction, the use of the Impella LP 2.5 is feasible and safe, and provides superior hemodynamic support compared with standard treatment using an IABP.

>In a review on circulatory assistance in acute heart failure, Hermansen and colleagues (2009) stated that the findings regarding the use of the Impella axial-flow recovery system for circulatory assistance in patients with acute heart failure, especially for those with cardiogenic shock not related to cardiac surgery, calls for cautious optimism.  Additionally, in a systematic review on the prevention and treatment of cardiogenic shock (O'Connor and Fraser, 2009), percutaneous LVADs are not listed as an option.

Furthermore, in a meta-analysis, Cheng et al (2009) evaluated potential benefits of percutaneous LVAD on hemodynamics and 30-day survival for the treatment of cardiogenic shock.  Two independent investigators searched Medline, Embase, and Cochrane Central Register of Controlled Trials for all controlled trials using percutaneous LVAD in patients with cardiogenic shock, where after data were extracted using standardized forms.  Weighted mean differences (MDs) were calculated for CI, mean arterial pressure (MAP), and pulmonary capillary wedge pressure (PCWP).  Relative risks (RRs) were calculated for 30-day mortality, leg ischemia, bleeding, and sepsis.  In main analysis, trials were combined using inverse-variance random effects approach.  Two trials evaluated the TandemHeart and a recent trial used the Impella device.  After device implantation, percutaneous LVAD patients had higher CI (MD 0.35 L/min/m(2), 95 % CI 0.09 to 0.61), higher MAP (MD 12.8 mmHg, 95 % CI 3.6 to 22.0), and lower PCWP (MD -5.3 mm Hg, 95 % CI -9.4 to -1.2) compared with patients who received IABP.  Similar 30-day mortality (RR 1.06, 95 % CI 0.68 to 1.66) was observed using percutaneous LVAD compared with IABP.  No significant difference was observed in incidence of leg ischemia (RR 2.59, 95 % CI 0.75 to 8.97) in percutaneous LVAD patients compared with IABP patients.  Bleeding (RR 2.35, 95 % CI 1.40 to 3.93) was significantly more observed in TandemHeart patients compared with patients treated with IABP.  The authors concluded that although percutaneous LVAD provides superior hemodynamic support in patients with cardiogenic shock compared with IABP, the use of these more powerful devices did not improve early survival.  These results do not yet support percutaneous LVAD as first-choice approach in the mechanical management of cardiogenic shock.