Lyle D. Joyce

Gastrointestinal bleeding rates in recipients of nonpulsatile and pulsatile left ventricular assist devices

OBJECTIVE Pulsatile and nonpulsatile left ventricular assist devices are effective in managing congestive heart failure. Despite early evidence for clinical efficacy, the long-term impact of nonpulsatile flow on end-organ function remains to be determined. Our goal was to compare rates of gastrointestinal bleeding in nonpulsatile and pulsatile device recipients. METHODS In a retrospective review of 101 left ventricular assist device recipients (55 nonpulsatile, 46 pulsatile) from October 31, 2003, to June 1, 2007, at a single center, gastrointestinal bleeding was defined as guaiac-positive stool with hemoglobin drop requiring transfusion of at least 2 units of packed red blood cells. To assess bleeding risk outside the initial postoperative course, any patients with a device in place for 15 days or less was excluded. RESULTS Twelve nonpulsatile and 3 pulsatile left ventricular assist device recipients had gastrointestinal bleeding 16 days or longer after device implantation. The event rates were 63 events/100 patient-years for nonpulsatile devices and 6.8 events/100 patient-years for pulsatile devices (P = .0004). This difference persisted for bleeding occurring 31 days or longer after device implantation, with 46.5 events/100 patient-years for nonpulsatile devices versus 4.7 events/100 patient-years for pulsatile devices (P = .0028). Mortalities were similar between groups (15% nonpulsatile vs 17% pulsatile, P = .6965). CONCLUSION Patients with nonpulsatile left ventricular assist devices appear to have a higher rate of gastrointestinal bleeding events than do pulsatile left ventricular assist device recipients. Further prospective evaluation is needed to determine potential etiologies and strategies for reducing gastrointestinal bleeding in this population.

Acquired von Willebrand Syndrome in Continuous-Flow Ventricular Assist Device Recipients

BACKGROUND Bleeding is a major cause of morbidity in recipients of continuous-flow left ventricular assist devices (CF-LVAD). A better understanding of the impact of CF-LVAD support on the hemostatic profile is necessary to establish better strategies for anticoagulation therapy and risk assessment for bleeding complications. A prospective multicenter study was conducted to characterize von Willebrand factor (vWF) profiles in patients undergoing CF-LVAD implantation. METHODS Blood samples were collected before and after CF-LVAD implantation from 37 patients between July 2008 and April 2009 at Duke University and the University of Minnesota. Blood samples were analyzed for vWF, platelet and collagen-binding ability. The presence of high-molecular-weight (HMW) vWF multimers were detected through gel electrophoresis, and deficiency was graded on a scale of 0 (normal) to 3 (severe loss). RESULTS All 37 patients exhibited significant loss of HMW vWF multimers within 30 days of CF-LVAD implantation. Ten of the 37 patients experienced bleeding complications after CF-LVAD placement. CONCLUSIONS All CF-LVAD recipients had acquired von Willebrand syndrome after LVAD placement, demonstrated by reduced or absent HMW vWF multimer levels. However, not all recipients had bleeding complications. These findings suggest that loss of HMW vWF multimers alone cannot predict bleeding risk. Further refinement of laboratory techniques and a larger follow-up is required to identify risk factors for bleeding in CF-LVAD recipients.

Improved Survival and Decreasing Incidence of Adverse Events With the HeartMate II Left Ventricular Assist Device as Bridge-to-Transplant Therapy

BACKGROUND Pulsatile left ventricular assist devices (LVADs) are effective as bridge-to-transplant therapy, but they are limited by their large size and lack of durability. Smaller, more durable, continuous flow devices such as the HeartMate II LVAD are increasingly being used. The aim of this study is to report our single-center experience with this device as bridge-to-transplant therapy. METHODS Overall, 47 patients received HeartMate II LVADs at our center from June 2005 to July 2007; 32 as bridge to transplant, 7 as destination therapy, and 8 as exchange therapy for a failed HeartMate XVE. We reviewed our experience with the device as bridge-to-transplant therapy and report on patient survival and adverse events. RESULTS The mean age of the bridge-to-transplant patients was 50.75 +/- 13.78 years; 10 (31.3%) were female. The cause of the underlying disease was ischemic in 18 patients (56.3%), idiopathic in 11 (34.4%), myocarditis in 1 (3.1%), postpartum cardiomyopathy in 1 (3.1%), and congenital heart disease in 1 (3.1%). The mean duration of HeartMate II support was 193.2 +/- 139.9 days. At 30 days after HeartMate II placement, the patient survival was 96.9% by Kaplan-Meier analysis; at 6 months (alive or transplanted), 86.9%. Major adverse events included bleeding requiring reexploration in 5 patients (15.6%), right ventricular failure requiring right ventricular assist device support in 2 (6.3%), LVAD-related infections in 4 (12.5%), neurologic or thromboembolic events in 2 (6.3%), and gastrointestinal bleeding in 5 (15.6%). We noted one serious device malfunction (3.1%) resulting in the patients death; in addition, 2 patients experienced pump thrombosis (6.3%). CONCLUSIONS Despite morbidity, use of the HeartMate II LVAD as bridge-to-transplant therapy is associated with excellent survival and low mortality rates. We found a marked decrease in morbidity related to right ventricular failure, to device-related infections, and to thromboembolic events. However, the requirements for anticoagulation therapy may be associated with increased mediastinal and gastrointestinal bleeding. Strategies to optimize anticoagulation therapy may further improve results for these critically ill patients.

Low thromboembolic risk for patients with the Heartmate II left ventricular assist device

OBJECTIVE Thromboembolic events can occur in up to 20% of patients with a left ventricular assist device. The aggressive use of anticoagulation with newer continuous-flow devices has potentially increased the risk of postoperative bleeding. The predecessor of the HeartMate II left ventricular assist device, the HeartMate XVE (Thoratec Corp, Pleasanton, Calif), was associated with an extremely low thromboembolic risk, even without anticoagulation, because of its unique textured surfaces. Even though several areas of the HeartMate II are textured, a protocol was adopted for this new axial flow pump requiring long-term anticoagulation with warfarin. In our study, we investigated whether the HeartMate II left ventricular assist device is associated with a similarly low thromboembolic risk as the HeartMate XVE. METHODS At our institution, 45 patients (mean age, 57.24 +/- 14.2 years) underwent implantation of the HeartMate II; 30 underwent bridge-to-transplantation therapy, 7 underwent destination therapy, and 8 underwent left ventricular assist device exchange for a failed XVE left ventricular assist device. Total duration of HeartMate II support was 352.13 patient-months (mean duration, 7.2 +/- 5.2 months). All 45 patients were treated postoperatively with warfarin and aspirin. We recorded use of these 2 medications and monthly international normalized ratios. Prospectively, we also monitored patients for any clinical thromboembolic events and for pump thrombus. RESULTS Of our 45 study patients, 41 had a mean international normalized ratio of less than 2.0; of those 41 patients, 21 had a mean international normalized ratio of less than 1.6. Because of recurrent gastrointestinal bleeding episodes, 7 patients discontinued warfarin for a total duration of 39.1 patient-months. During the entire period of HeartMate II support, we noted 1 thromboembolic event. In addition, another patient had a suspected left ventricular assist device pump thrombus that resolved with a high-intensity heparin anticoagulation protocol (international normalized ratio, 1.3). CONCLUSIONS Our preliminary single-center analysis suggests that the HeartMate II is associated with an extremely low thromboembolic risk and with less stringent requirements for anticoagulation. Selected patients at high risk for bleeding can be safely followed with either no or extremely low anticoagulation requirements for prolonged periods.

Readmissions after implantation of axial flow left ventricular assist device.

OBJECTIVES The purpose of this study was to determine the occurrence and causes of readmissions after implantation of axial flow left ventricular assist device (LVAD). BACKGROUND Based on the REMATCH (Randomized Evaluation of Mechanical Assistance for the Treatment of Congestive Heart Failure) study experience, readmissions after LVAD implantation are thought to be frequent. METHODS We retrospectively analyzed admissions to our facility in a cohort of 115 patients implanted between January 2008 and July 2011 with the HeartMate II axial flow LVAD, of whom 42 were bridged to transplant. To account for repeated events, Andersen-Gill models were used to determine possible predictors. RESULTS The patients were followed for 1.4 ± 0.9 years. There were 224 readmissions in 83 patients. The overall readmission rate was 1.64 ± 1.97 per patient-year of follow-up. The readmission rate for the first 6 months was 2.0 ± 2.3 and decreased to 1.2 ± 2.1 during subsequent follow-up. Leading causes were bleeding (66 readmissions in 34 patients), mostly gastrointestinal bleed (51 in 27 patients), cardiac (51 in 36 patients, most for HF or arrhythmia), infections (32 in 25 patients) of which 6 were pump related, and thrombosis (20 in 15 patients) including 13 readmissions due to hemolysis. Preoperative variables associated with (fewer) readmissions in a multivariate model include residence within our hospital-extended referral zone of Minnesota and the neighboring states (hazard ratio: 0.66; 95% confidence interval: 0.48 to 0.91; p = 0.011), hemoglobin (hazard ratio: 0.91, 95% confidence interval: 0.84 to 0.99; p = 0.027) and N-terminal pro-B-type natriuretic peptide (hazard ratio: 0.98; 95% confidence interval: 0.96 to 1.0 per 1,000-unit increase, p = 0.022). C-statistic for the model: 0.63. CONCLUSIONS Readmission rates after axial flow LVAD implantation decrease during the first 6 months and then stabilize. The leading causes are bleeding, cardiac (heart failure and arrhythmia), infections, and thrombosis.

Multiple arterial grafts improve late survival of patients undergoing coronary artery bypass graft surgery: analysis of 8622 patients with multivessel disease.

Background— Use of the left internal mammary artery (LIMA) in multivessel coronary artery disease improves survival after coronary artery bypass graft surgery; however, the survival benefit of multiple arterial (MultArt) grafts is debated. Methods and Results— We reviewed 8622 Mayo Clinic patients who had isolated primary coronary artery bypass graft surgery for multivessel coronary artery disease from 1993 to 2009. Patients were stratified by number of arterial grafts into the LIMA plus saphenous veins (LIMA/SV) group (n=7435) or the MultArt group (n=1187). Propensity score analysis matched 1153 patients. Operative mortality was 0.8% (n=10) in the MultArt and 2.1% (n=154) in the LIMA/SV (P=0.005) group, which was not statistically different (P=0.996) in multivariate analysis or the propensity-matched analysis (P=0.818). Late survival was greater for MultArt versus LIMA/SV (10- and 15-year survival rates were 84% and 71% versus 61% and 36%, respectively [P<0.001], in unmatched groups and 83% and 70% versus 80% and 60%, respectively [P=0.0025], in matched groups). MultArt subgroups with bilateral internal mammary artery/SV (n=589) and bilateral internal mammary artery only (n=271) had improved 15-year survival (86% and 76%; 82% and 75% at 10 and 15 years [P<0.001]), and patients with bilateral internal mammary artery/radial artery (n=147) and LIMA/radial artery (n=169) had greater 10-year survival (84% and 78%; P<0.001) versus LIMA/SV. In multivariate analysis, MultArt grafts remained a strong independent predictor of survival (hazard ratio, 0.79; 95% confidence interval, 0.66–0.94; P=0.007). Conclusions— In patients undergoing isolated coronary artery bypass graft surgery with LIMA to left anterior descending artery, arterial grafting of the non–left anterior descending vessels conferred a survival advantage at 15 years compared with SV grafting. It is still unproven whether these results apply to higher-risk subgroups of patients.

Effects of Centrifugal, Axial, and Pulsatile Left Ventricular Assist Device Support on End-Organ Function in Heart Failure Patients

PURPOSE Newer continuous-flow left ventricular assist devices (LVAD) have the advantage of smaller size and increased durability. Questions remain regarding the safety and effects of long-term nonpulsatile flow, despite some animal and human studies showing that end-organ function is well maintained with pulsatile or axial-flow devices. This study investigated whether centrifugal devices have similar effects on end-organ function. METHODS All patients who underwent LVAD implantation as bridge-to-transplant (BTT) therapy from January 2004 through May 2007 were reviewed. Excluded were patients on biventricular support, destination therapy, temporary support, and patients who died within 30 days after LVAD implantation. The centrifugal device was the VentrAssist (Ventracor Ltd, Sydney, Australia); axial, the HeartMate II; and pulsatile, the HeartMate XVE (Thoratec Corp, Pleasanton, CA). RESULTS During the study, 10 VentrAssist, 30 HeartMate II, and 18 HeartMate XVE devices were implanted. Among the 3 groups, age, gender, weight, duration of LVAD support, and cause of heart failure were comparable. No significant differences were found between groups with respect to baseline renal function, hepatic function, or hematologic function. At 1 and 3 months of follow-up, renal and hepatic function either improved or remained within normal limits in all groups. CONCLUSIONS Centrifugal, axial, and pulsatile LVADs all provide adequate circulatory support to maintain appropriate end-organ function in patients with end-stage heart failure. The advantages of the newer continuous-flow devices can be safely applied to an increasing number of patients. Long-term studies (>1 year) are needed to assess effects on end-organ function with continuous-flow devices, which may have important implications for use as destination therapy.

Outcomes of a multicenter trial of the Levitronix CentriMag ventricular assist system for short-term circulatory support

OBJECTIVE The Levitronix CentriMag (Levitronix LLC, Waltham, Mass) ventricular assist system is designed for temporary left, right, or biventricular support. Advantages include ease of use, excellent reliability, and low thrombosis risk,. which may allow wider application of short-term support and improved outcomes in patients with cardiogenic shock. This multi-institutional study evaluated safety, effectiveness, and outcomes of the CentriMag in patients with cardiogenic shock. METHODS Thirty-eight patients were supported at 7 centers. Patients included 12 after cardiotomy, 14 after myocardial infarction, and 12 with right ventricular failure after implantable left ventricular assist device placement. Devices were implanted in left (n = 8), right (n = 12), or biventricular (n = 18) configuration. Support was continued until recovery, transplantation, or implantation of long-term ventricular assist device. RESULTS Mean support duration for the entire cohort (n = 38) was 13 days (1-60 days), with 47% of patients (18/38) surviving 30 days after device removal. Mean CentriMag biventricular support (n = 18) duration was 15 days (1-60 days), with 44% (8/18) surviving at 30 days. Mean CentriMag right ventricular support with a commercially available left ventricular assist device (n = 12) duration was 14 days (1-29 days), with 58% (7/12) surviving at 30 days. Complications included bleeding (21%), infection (5%), respiratory failure (3%), hemolysis (5%), and neurologic dysfunction (11%). There were no CentriMag or pump failures. CONCLUSIONS In this preliminary study, the CentriMag provided short-term support for patients with cardiogenic shock with a low incidence of device-related complications and no device failures.

Changes in renal function after implantation of continuous-flow left ventricular assist devices.

OBJECTIVES The aim of this study was to determine renal outcomes after left ventricular assist device (LVAD) implantation. BACKGROUND Renal dysfunction before LVAD placement is frequent, and it is unclear whether it is due to primary renal disease or to poor perfusion. METHODS A retrospective single-center analysis was conducted in 83 consecutive patients implanted with HeartMate II continuous-flow LVADs (Thoratec Corp., Pleasanton, California). Calculated glomerular filtration rate (GFR) was assessed on admission and 1, 3, and 6 months after implantation. To define predictors for improvement in GFR, clinical variables were examined in patients with decreased renal function (GFR <60 ml/min/1.73 m(2)) before LVAD, surviving and dialysis-free at 1 month (n = 44). RESULTS GFR significantly increased from admission (53.2 ± 21.4 ml/min/1.73 m(2)) to 1 month after LVAD implantation (87.4 ± 27.9 ml/min/1.73 m(2)) (p < 0.0001). Subsequently, at 3 and 6 months, GFR remained significantly (p < 0.0001) above pre-LVAD values. Of the 51 patients with GFRs <60 ml/min/1.73 m(2) before LVAD surviving at 1 month, 34 (67%) improved to GFRs >60 ml/min/1.73 m(2). Univariate pre-operative predictors for improvement in renal function at 1 month included younger age (p = 0.049), GFR improvement with optimal medical therapy (p < 0.001), intra-aortic balloon pump use (p = 0.004), kidney length above 10 cm (p = 0.023), no treatment with angiotensin-converting enzyme inhibitors or angiotensin receptor blockers (p = 0.029), higher bilirubin (p = 0.002), higher Lietz-Miller score (p = 0.019), and atrial fibrillation (p = 0.007). Multivariate analysis indicated pre-operative improved GFR (slope = 0.5 U per unit improved; 95% confidence interval: 0.2 to 0.8; p = 0.003), atrial fibrillation (slope = 27; 95% confidence interval: 8 to 46; p = 0.006), and intra-aortic balloon pump use (slope = 14; 95% confidence interval: 2 to 26; p = 0.02) as independent predictors. CONCLUSIONS In most patients with end-stage heart failure considered for LVAD implantation, renal dysfunction is reversible and likely related to poor renal perfusion.

Bilateral Internal Thoracic Artery Harvest and Deep Sternal Wound Infection in Diabetic Patients

BACKGROUND Coronary artery bypass graft surgery is superior to percutaneous intervention in diabetic patients with multivessel disease. The use of bilateral internal thoracic arteries (BITA) may provide better long-term graft patency, but the risk of postoperative deep sternal wound infection has limited its use in diabetic patients. However, studies have reported conflicting results, and require systematic evaluation. METHODS MEDLINE, EMBASE, World of Science, and the Cochrane library were searched for randomized controlled trials and observational studies comparing the incidence of deep sternal wound infection in diabetic patients undergoing either left internal thoracic artery (LITA) or BITA harvest. We used random effect models to compare risk ratios within groups. RESULTS One randomized controlled trial and 10 observational studies (126,235 diabetic patients: 122,465 LITA, 3,770 BITA) met inclusion criteria. Deep sternal wound infection occurred in 3.1% and 1.6% for the BITA and LITA cohorts, respectively. The risk ratio for deep sternal wound infection development was 1.71 (1.37 to 2.14) for BITA compared with LITA. Patients who underwent skeletonized BITA harvest had a similar risk of deep sternal wound infection compared with LITA (0.9 [0.42 to 2.09]), although pedicled harvest demonstrated increased risk (1.77 [1.4 to 2.23]). Early mortality was comparable in the LITA cohort (2.5%) and the BITA cohort (2.3%; p = 0.8). CONCLUSIONS The risk of deep sternal wound infection can be minimized in diabetic patients undergoing coronary artery bypass graft surgery by performing ITA harvested in a skeletonized manner with meticulous attention to preserving sternal blood flow. Pedicled harvest is to be discouraged when utilizing both ITA owing to a significant increase in the risk of postoperative deep sternal wound infection.