Yoshifumi Naka

Results of the Post-U.S. Food and Drug Administration-Approval Study With a Continuous Flow Left Ventricular Assist Device as a Bridge to Heart Transplantation: A Prospective Study Using the INTERMACS (Interagency Registry for Mechanically Assisted Circulatory Support)

OBJECTIVES The aim of this study was to determine whether results with the HeartMate (HM) II left ventricular assist device (LVAD) (Thoratec Corporation, Pleasanton, California) in a commercial setting are comparable to other available devices for the same indication. BACKGROUND After a multicenter pivotal clinical trial conducted from 2005 to 2008, the U.S. Food and Drug Administration approved the HM II LVAD for bridge to transplantation (BTT). A post-approval study was required by the U.S. Food and Drug Administration to determine whether results with the device in a commercial setting are comparable to other available devices for the same indication. METHODS The study was a prospective evaluation of the first 169 consecutive HM II patients enrolled in the national INTERMACS (Interagency Registry for Mechanically Assisted Circulatory Support) who were listed for transplant or likely to be listed. Patients were enrolled from April through August 2008 at 77 U.S. centers and followed for at least 1 year after implant. A comparison group (COMP) included all patients (n = 169 at 27 centers) enrolled in the INTERMACS registry with other types of LVADs (79% HeartMate XVE, 21% Implantable Ventricular Assist Device [Thoratec Corporation]) for the same BTT indication in the same time period. Survival rates, adverse events, and quality of life with the EuroQol EQ-5D visual analog scale were obtained in the INTERMACS registry. RESULTS Baseline characteristics were similar, but creatinine and blood urea nitrogen were lower in the HM II versus COMP groups, and there were fewer patients in the highest-risk INTERMACS patient profile Number 1 (24% for HM II vs. 39% for COMP). Adverse event rates were similar or lower for HM II versus COMP for all events. Bleeding was the most frequent adverse event for both groups (1.44 vs. 1.79 events/patient-year). Operative 30-day mortality for HM II was 4% versus 11% for COMP. The percentage of patients reaching transplant, cardiac recovery, or ongoing LVAD support by 6 months was 91% for HM II and 80% for COMP, and the Kaplan-Meier survival for patients remaining on support at 1 year was 85% for HM II versus 70% for COMP. Quality of life was significantly improved at 3 months of support and sustained through 12 months in both groups compared with baseline. CONCLUSIONS The results in a post-market approval, actual patient care setting BTT population support the original findings from the pivotal clinical trial regarding the efficacy and risk profile of the HM II LVAD. These data suggest that dissemination of this technology after approval has been associated with continued excellent results.

Surgical management of valvular disease in patients requiring left ventricular assist device support

BACKGROUND Success with long-term implantable left ventricular assist devices (LVAD) has led to increased use in patients previously thought to be unsuitable for mechanical circulatory assistance. Patients with preexisting or newly diagnosed valvular disease have been traditionally excluded from device placement. The purpose of this study was to review our experience with LVAD support in patients with valvular disease and to develop a management algorithm for these difficult patients. METHODS We reviewed the clinical records of 199 consecutive patients who received the ThermoCardiosystems, Inc, HeartMate Pneumatic or Vented Electric LVAD. There were 18 patients (9%) who required surgical management of native or prosthetic valvular disease during LVAD implantation. RESULTS Suture or patch closure of the aortic valve was performed in 6 patients, aortic valve plication and repair in 1 patient, mitral valve repair in 4 patients, and tricuspid valve annuloplasty in 5 patients. Two patients with mechanical mitral valve prostheses were treated with postoperative warfarin anticoagulation. Fifteen of the 18 patients with valvular pathology survived the immediate postoperative period (17% mortality). Eleven patients have either undergone transplantation or continue to be supported with an LVAD (61%). Operative mortality in LVAD patients without concomitant valve repair was 18% (n = 33) with a late mortality of 7% (n = 13). Seven of these late deaths occurred in patients who received a device as destination therapy. In the remaining 6 patients, the cause of death was sepsis (n = 2), multisystem organ failure (n = 2), driveline rupture (n = 1), and massive gastrointestinal bleed (n = 1). CONCLUSIONS Preexisting native or prosthetic valve pathology does not increase the immediate perioperative risk of LVAD insertion; however, these patients continue to pose a challenge for postoperative management while awaiting transplantation.

Continuous Flow Left Ventricular Assist Device Outcomes in Commercial Use Compared With the Prior Clinical Trial

BACKGROUND A multicenter clinical trial conducted from 2005 to 2008 of a continuous flow left ventricular assist device (LVAD) resulted in Food and Drug Administration approval for bridge to transplantation. The purpose of this analysis was to determine changes in posttrial outcomes in widespread commercial use since the clinical trial. METHODS We compared outcomes of 486 patients who received a continuous flow LVAD as a bridge to transplantation at 36 centers during the clinical trial (March 2005 to April 2008) with outcomes of 1,496 posttrial patients who received a continuous flow LVAD at 83 centers (April 2008 to September 2010 as reported to the Interagency Registry for Mechanically Assisted Circulatory Support). RESULTS Baseline data were comparable between groups. Cumulative follow-up was 511 and 1,082 patient-years for trial and posttrial patients, respectively, and average support duration was 12.6 ± 14.0 and 8.7 ± 7.1 months. Kaplan-Meier survival improved at 1 year from 76% (trial) to 85% (posttrial). The percentage of patients undergoing transplantation in the first year decreased from 48% in the trial period to 39% in the posttrial period. Quality of life metrics improved by 3 months in both groups. CONCLUSIONS The survival rate of a large group of continuous flow LVAD patients in a real-world setting after Food and Drug Administration market approval for bridge to transplantation has improved since the clinical trial. These data show that excellent outcomes have been maintained with dissemination of new LVAD technology from a clinical trial phase to more broad based use in the period after market approval.

The RECOVER I: A multicenter prospective study of Impella 5.0/LD for postcardiotomy circulatory support

OBJECTIVES Cardiogenic shock after cardiac surgery is accompanied by a high mortality rate. Early institution of hemodynamic support with a versatile, easy to insert left ventricular assist device might help bridge patients to recovery or to the next therapy, and improve the outcomes. METHODS Patients developing cardiogenic shock or low cardiac output syndrome after being weaned off cardiopulmonary bypass were enrolled in a prospective single-arm feasibility study (RECOVER I). The primary safety endpoint was the frequency of major adverse events (death, stroke) at 30 days or discharge, whichever was longer. The primary efficacy endpoint was survival of the patient to implementation of the next therapy, which included recovery at 30 days after device removal and bridge-to-other-therapy. RESULTS Sixteen patients provided informed consent and were enrolled in the study. Hemodynamics improved immediately after the initiation of mechanical support: cardiac index, 1.65 versus 2.7 L/min/m(2) (P = .0001); mean arterial pressure, 71.4 versus 83.1 mm Hg (P = .01); and pulmonary artery diastolic pressure, 28.0 versus 19.8 mm Hg (P < .0001). The pump provided an average of 4.0 ± 0.6 L/min of flow for an average duration of 3.7 ± 2.9 days (range, 1.7-12.6). The primary safety endpoint occurred in 2 patients (13%; 1 stroke and 1 death). For the primary efficacy endpoint, recovery of the native heart function was obtained in 93% of the patients discharged, with bridge-to-other-therapy in 7%. Survival to 30 days, 3 months, and 1 year was 94%, 81%, and 75%, respectively. CONCLUSIONS The use of the Impella 5.0/left direct device is safe and feasible in patients presenting with postcardiotomy cardiogenic shock. The device was rapidly inserted, enabled early support, and yielded favorable outcomes.

Impact of concurrent surgical valve procedures in patients receiving continuous-flow devices

BACKGROUND Preexisting valve pathology is common in patients with end-stage heart failure undergoing left ventricular assist device (LVAD) placement. The indications and subsequent benefits of performing valvular procedures in these patients are unclear. The objective of this study was to determine the impact of performing concurrent surgical valve procedures in a large cohort of patients receiving LVADs. METHODS One thousand one hundred six patients received the HeartMate II (HMII) LVAD in the bridge to transplant (n = 470) and destination therapy (n = 636) clinical trials. Of these, 374 patients (34%) had concurrent cardiac surgery procedures as follows: 242 patients (21%) with 281 concurrent valve procedures (VP) (aortic 80, mitral 45, and tricuspid 156), and 641 patients had only HMII LVAD. The focus of this study was to determine the clinical outcomes of patients undergoing HMII + VP compared with those who received HMII alone. RESULTS Patients undergoing HMII + VP were significantly older, had higher blood urea nitrogen levels and central venous pressure, and decreased right ventricular stroke work index; intraoperatively, the median cardiopulmonary bypass times were also longer. The unadjusted 30-day mortality was significantly higher in patients undergoing HMII + VP (10.3% vs 4.8% for LVAD alone, P = .005). Subgroup analysis of individual VPs showed that higher mortality occurred in patients with HMII plus 2 or more VPs (13.5%, P = .04) followed by trends for increased mortality with HMII plus mitral alone (11.5%, P = NS), HMII plus aortic alone (10.9%, P = NS), and HMII plus tricuspid (8.9%, P = NS) procedures. Of these various groups, only patients undergoing HMII + isolated aortic VP (P = .001) and HMII + multiple VPs (P = .046) had significantly worse long-term survival compared with patients undergoing HMII alone. Right heart failure and right ventricular assist device use was increased in patients undergoing VPs, but there was no difference in the incidence of bleeding or stroke. CONCLUSIONS Patients frequently require concurrent VPs at the time of LVAD placement; these patients are sicker and have higher early mortality. Furthermore, right ventricular dysfunction is increased in these patients. Further studies to develop selection criteria for concurrent valve interventions are important to further improve clinical outcomes.

SdrF, a Staphylococcus epidermidis surface protein, contributes to the initiation of ventricular assist device driveline-related infections.

Staphylococcus epidermidis remains the predominant pathogen in prosthetic-device infections. Ventricular assist devices, a recently developed form of therapy for end-stage congestive heart failure, have had considerable success. However, infections, most often caused by Staphylococcus epidermidis, have limited their long-term use. The transcutaneous driveline entry site acts as a potential portal of entry for bacteria, allowing development of either localized or systemic infections. A novel in vitro binding assay using explanted drivelines obtained from patients undergoing transplantation and a heterologous lactococcal system of surface protein expression were used to identify S. epidermidis surface components involved in the pathogenesis of driveline infections. Of the four components tested, SdrF, SdrG, PIA, and GehD, SdrF was identified as the primary ligand. SdrF adherence was mediated via its B domain attaching to host collagen deposited on the surface of the driveline. Antibodies directed against SdrF reduced adherence of S. epidermidis to the drivelines. SdrF was also found to adhere with high affinity to Dacron, the hydrophobic polymeric outer surface of drivelines. Solid phase binding assays showed that SdrF was also able to adhere to other hydrophobic artificial materials such as polystyrene. A murine model of infection was developed and used to test the role of SdrF during in vivo driveline infection. SdrF alone was able to mediate bacterial adherence to implanted drivelines. Anti-SdrF antibodies reduced S. epidermidis colonization of implanted drivelines. SdrF appears to play a key role in the initiation of ventricular assist device driveline infections caused by S. epidermidis. This pluripotential adherence capacity provides a potential pathway to infection with SdrF-positive commensal staphylococci first adhering to the external Dacron-coated driveline at the transcutaneous entry site, then spreading along the collagen-coated internal portion of the driveline to establish a localized infection. This capacity may also have relevance for other prosthetic device–related infections.

Continuous-flow left ventricular assist devices and usefulness of a standardized strategy to reduce drive-line infections

BACKGROUND Drive-line infection (DLI) is a common complication of left ventricular assist device (LVAD) support, leading to significant morbidity that jeopardizes the benefits of these devices. It has been reported that DLI incidence is related to drive-line dressing strategies. The aim of this study was to determine whether implementation of a standardized drive-line care kit would reduce the incidence of DLIs. METHODS DLI data were collected prospectively on all LVAD patients implanted between 2009 and 2013 at Columbia University Medical Center. Drive-line care was altered on June 1, 2011, from a dry sterile dressing without a standard anchoring device to a standardized kit, which included silver gauze dressing and a standard anchoring device. The silver dressing was used until the wound incorporated, with a minimum of 1 month. RESULTS During the study period, 107 patients were implanted with LVADs before implementation of a standardized kit (Group A) and 159 thereafter (Group B). Median follow-up time (censoring at June 2011) for Group A was 8.73 (IQR 3.51 to 17.47) months and 11.65 (IQR 6.66 to 35.20) months for Group B (p = 0.17). DLI event rate improved from 0.18 to 0.07 event per patient-year, corresponding to a relative risk reduction of 62.5%. In addition, the 1-year freedom from infection was significantly increased in Group B (92.46%) compared with Group A (81.94%) (log rank = 0.036). CONCLUSION The use of a standardized kit, including silver dressing and a standard anchoring device, leads to decrease in DLI with an absolute risk reduction of 11%. Routine use of these dressing techniques is warranted based on our findings, and may lead to reduction of complications related to infections.

Del Nido Cardioplegia can be safely administered in high-risk coronary artery bypass grafting surgery after acute myocardial infarction: a propensity matched comparison

ObjectiveDel Nido (DN) cardioplegia solution provides a depolarized hyperkalemic arrest lasting up to 60 minutes, and the addition of lidocaine may limit intracellular calcium influx. Single-dose DN cardioplegia solution may offer an alternative myocardial protection strategy to multi-dose cold whole blood (WB) cardioplegia following acute myocardial infarction (AMI).MethodsWe retrospectively reviewed 88 consecutive patients with AMI undergoing coronary artery bypass (CABG) surgery with cardioplegic arrest between June 2010 to June 2012. Patients exclusively received WB (n = 40, June 2010-July 2011) or DN (n = 48, August 2011-June 2012) cardioplegia. Preoperative and postoperative data were retrospectively reviewed and compared using propensity scoring.ResultsNo significant difference in age, maximum preoperative serum troponin level, ejection fraction, and STS score was present between DN and WB. A single cardioplegia dose was given in 41 DN vs. 0 WB patients (p < 0.001), and retrograde cardioplegia was used 10 DN vs. 31 WB patients (p < 0.001). Mean cardiopulmonary bypass and cross clamp times were significantly shorter in the DN group versus WB group. Tranfusion rate, length of stay, intra-aortic balloon pump requirement, post-operative inotropic support, and 30-day mortality was no different between groups. One patient in the WB group required a mechanical support due to profound cardiogenic shock.ConclusionsDN cardioplegia may provide equivalent myocardial protection to existing cardioplegia without negative inotropic effects in the setting of acute myocardial infarction.

Device exchange in HeartMate II recipients: long-term outcomes and risk of thrombosis recurrence.

Successful long-term use of the HeartMate II (HM II) left ventricular assist device has become commonplace but may be complicated by mechanical failure, infection, or thrombosis necessitating device exchange (DE). A subcostal approach to device exchange with motor exchange only is less traumatic, but long-term outcomes have not been reported. A retrospective chart review of all patients who required HM II to HM II device exchange at our institution was conducted. Of the 232 HM II patients implanted between January 2008 and July 2013, 28 required 36 device exchanges during a follow-up of 33.72 ± 17.25 months. The Kaplan–Meier 1 year survival was 63% for sternotomy exchanges and 100% for subcostal exchanges. Twenty-one exchanges were performed for initial or recurring device thrombosis. Although there was no difference in the risk of subsequent thrombosis after subcostal versus sternotomy exchange, the overall risk of recurring device thrombosis after device exchange for the same was high (31%). HM II device exchange via the subcostal approach has excellent short- and long-term outcomes. Device exchange performed for thrombosis is associated with a high recurrence risk irrespective of surgical approach

Attenuation of the unfolded protein response and endoplasmic reticulum stress after mechanical unloading in dilated cardiomyopathy

Abnormal intracellular calcium (Ca(2+)) handling can trigger endoplasmic reticulum (ER) stress, leading to activation of the unfolded protein response (UPR) in an attempt to prevent cell death. Mechanical unloading with a left ventricular assist device (LVAD) relieves pressure-volume overload and promotes reverse remodeling of the failing myocardium. We hypothesized that mechanical unloading would alter the UPR in patients with advanced heart failure (HF). UPR was analyzed in paired myocardial tissue from 10 patients with dilated cardiomyopathy obtained during LVAD implantation and explantation. Samples from healthy hearts served as controls. Markers of UPR [binding immunoglobulin protein (BiP), phosphorylated (P-) eukaryotic initiation factor (eIF2α), and X-box binding protein (XBP1)] were significantly increased in HF, whereas LVAD support significantly decreased BiP, P-eIF2α, and XBP1s levels. Apoptosis as reflected by C/EBP homologous protein and DNA damage were also significantly reduced after LVAD support. Improvement in left ventricular dimensions positively correlated with P-eIF2α/eIF2α and apoptosis level recovery. Furthermore, significant dysregulation of calcium-handling proteins [P-ryanodine receptor, Ca(2+) storing protein calsequestrin, Na(+)-Ca(2+) exchanger, sarcoendoplasmic reticulum Ca(2+)-ATPase (SERCA2a), ER chaperone protein calreticulin] was normalized after LVAD support. Reduced ER Ca(2+) content as a causative mechanism for UPR was confirmed using AC16 cells treated with a calcium ionophore (A23187) and SERCA2a inhibitor (thapsigargin). UPR activation and apoptosis are reduced after mechanical unloading, which may be mediated by the improvement of Ca(2+) handling in patients with advanced HF. These changes may impact the potential for myocardial recovery.