Lessons learned from the first 200 LVAD implants and beyond
The mechanical circulatory assist device program at Mayo Clinic in Rochester, Minn., was formally established in 2007 to address the needs of an advanced heart failure population demonstrated to benefit from such support even in the absence of proceeding to transplant. Until then, no more than 10 left ventricular assist devices (LVADs) had been implanted in any single year at Mayo Clinic in Rochester. This year, the program celebrated the 200th continuous-flow LVAD implant since 2007; to date, a total of 223 long-term continuous-flow LVADs have been implanted, and four patients with biventricular heart failure have received total artificial hearts with subsequent heart transplantation.
A unique patient population
LVAD therapy can be offered to patients with advanced heart failure either as a bridge to transplant or destination therapy (in patients who are not transplant candidates). Bridge-to-transplant patients will remain on device therapy until a donor heart becomes available and they undergo transplantation. Destination therapy patients receive the device and remain on device support for the rest of their lives.
Patients who are bridge-to-transplant candidates tend to be younger and without serious comorbid conditions; patients who are destination therapy candidates tend to be older and often possess various comorbid conditions that preclude them from being considered for transplant. In some cases, LVAD therapy can modify a comorbid condition such that a patient can become suitable for transplant, such as in the reversal of severe pulmonary hypertension. This is referred to as the bridge-to-decision strategy.
The majority of centers implant LVADs for patients as a bridge to transplant. In contrast, the majority of patients at Mayo Clinic receive LVAD therapy as destination therapy. "Subsequently, compared to all the clinical trials reporting results for device therapy, our patients on average are five to 10 years older at the time of implant and have more comorbidities, such as compromised pulmonary and renal function," according to John M. Stulak, M.D., transplant surgeon at Mayo Clinic in Rochester. Nevertheless, outcomes parallel and often exceed those reported in clinical trials.
The etiology of heart failure in the majority of patients is either ischemic or idiopathic dilated; however, there is an increased frequency of patients with end-stage congenital heart disease, restrictive and hypertrophic cardiomyopathy, and senile amyloidosis. These diagnoses are quite challenging when it comes to considering device therapy, and the patient-selection process is continually refined when considering device therapy in these patients.
Patient selection for LVAD therapy
"In general, selecting the appropriate patients for LVAD therapy is critical, as patient condition at the time of presentation is very closely tied to early and late outcomes," says John A. Schirger, M.D., transplant cardiologist at Mayo Clinic in Rochester. "When referral is very late in the disease process, patients are at significantly higher risk of early mortality and prolonged hospitalization." Identifying a patient who has a poor prognosis and poor functional capacity with or without recent hospitalizations allows for patients to undergo implantation with lower early risk. End-organ derangements are adverse predictors of outcome, as is poor nutritional status manifested as cardiac cachexia. Device therapy is best instituted electively, and early referral with close follow-up allows for optimizing timing of LVAD implantation.
In the case of a significantly decompensated patient with more severe end-organ dysfunction, temporary mechanical support can be utilized to ascertain whether long-term LVAD therapy is appropriate. LVAD therapy should not be viewed simply as an alternative to death, but rather as a bridge to life and indeed an improved quality of life. Early referral and appropriate timing of implant help in the attainment of these goals.
A team of cardiologists, surgeons, coordinators, nurses and social workers is involved in the preoperative evaluation of patients with advanced heart failure; team members are available 24/7 for evaluation of potential LVAD patients. Additionally, potential LVAD recipients meet with a palliative care team prior to implantation. Traditionally, palliative care teams have been engaged during end of life for comfort care, but Mayo Clinic has been at the forefront of utilizing these skill sets preoperatively to review and discuss goals of care and methods of enhancing quality of life after LVAD implant.
Follow-up, lifestyle modifications and LVAD-related complications
Close collaboration with local physicians is required in caring for patients after LVAD implantation. Team members at Mayo Clinic in Rochester have provided training at facilities in the care area regarding the special needs of these patients. Additionally, a standardized protocol has been developed to ensure appropriate scheduling of follow-up tests and visits. In between visits at Mayo Clinic, the team maintains very close contact with local physicians to coordinate the LVAD patient's care.
After LVAD implantation, patients have normal postsurgical activity restrictions with some particular additions unique to the LVAD. Patients are counseled to avoid static electricity, soaking and submerging in water (due to the infection risk of the percutaneous driveline), sleeping in a prone position, and driving. While there are no specific laws regarding driving, it is recommended that patients not drive after LVAD implantation due to uncertain liability in the event of a motor vehicle accident. Travel, especially internationally, also poses problems. Issues that need to be resolved prior to travel abroad include:
- Power conversion
- Medical letters
- Airline notification
- Security clearance
- Notification of local LVAD centers in proximity to the patient's destination
While on device support, patients can experience an array of LVAD-related medical issues that may require attention, including:
- Bleeding (most commonly gastrointestinal)
- Thromboembolic events (stroke or pump thrombosis)
- Right ventricular failure (manifested by fluid retention and renal insufficiency)
- Suction events (rapid drops in pump speed followed by an increase to the set value)
Despite these challenges, patients report an improved quality of life in addition to clearly demonstrable improvements in survival and exercise capacity.
Advances in the field of mechanical circulatory support are focused in two areas: device innovation and refinement in patient selection.
In terms of device innovation, there is continued miniaturization of pumps and improvements in design such that enhanced biocompatibility will hopefully translate into increased durability. The team at Mayo Clinic in Rochester has been active in all major device trials to date and is participating in upcoming device trials.
In terms of patient selection, there is current research focusing on the application of LVAD therapy in less-ill individuals. Currently, patients are considered candidates for LVAD therapy when in New York Heart Association (NYHA) Functional Capacity IV (and select patients in late NYHA Functional Capacity IIIB). Both the ROADMAP and REVIVE-IT clinical trials focus on rigorously evaluating LVAD therapy in more-functional individuals.
The VAD generation
With the dramatic increase in the application of LVAD therapy worldwide, there will be unmet clinical needs for these patients. In order to adequately care for these patients, more rehabilitation units, dialysis units, care facilities dealing with senility, wound centers and nutrition centers (just to name a few) will need to have specialty training to effectively care for LVAD patients.
The VAD generation is a group of patients who are no longer facing death as a result of heart failure and are subsequently aggregating into a considerable subset of geriatric medicine. They have special needs and circumstances that are not necessarily understood by the general public, medical society or even family members. Awareness of these many issues is crucial to ensure that their needs are able to be met.
For more information
Thoratec Corporation. Risk assessment and comparative effectiveness of left ventricular assist device (LVAD) and medical management (ROADMAP). ClinicalTrials.gov.
University of Michigan. The evaluation of VAD intervention before inotropic therapy (REVIVE-IT). ClinicalTrials.gov.
Feb. 19, 2014