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The left ventricular assist device (LVAD) is a mechanical pump that supplements or replaces the function of a damaged left ventricle. Although LVAD support is associated with improved survival and quality of life, infectious complications remain a major limitation. The authors examine the epidemiology of LVAD-associated infections and review current diagnostic, treatment, and management strategies. Novel evidence-based approaches to infection prevention remain critical because the number of patients receiving long-term mechanical support continues to burgeon.

The Fourth Annual Report of the Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS) summarizes and analyzes the first 5 years of patient and data collection. With more than 4,000 patients entered into the database, the evolution of pump technology, strategy at implant, and pre-implant patient profiles are chronicled. A risk factor analysis of the entire adult primary implant population is provided, and the recent composition of patient profiles is examined. Current actuarial survival with continuous-flow pumps exceeds 80% at 1 year and 70% at 2 years.

Delayed sternal closure (DSC) is employed after conventional cardiac surgery without a significantly increased risk of late mediastinitis or sternal wound infection. There are no data specifically examining its late effects on patients undergoing implantation with a ventricular assist device (VAD).Between October 1996 and October 2010, 364 patients underwent primary VAD implant and DSC was utilized in 184 (51%) patients for coagulopathy (n = 155; 84%), hemodynamic instability (n = 103; 56%), isolated right ventricular dysfunction (n = 15; 8%) or unspecified reasons (n = 17; 9%).Median duration of DSC was 1 day (range 1 to 7 days). Patients with DSC were older (54.5 vs. 50.3 years, p = 0.002), had a higher incidence of previous sternotomy (42% vs. 28%, p = 0.005), pre-operative intra-aortic balloon pump (50% vs. 30%, p0.001), pre-operative temporary extracorporeal mechanical circulatory support (23% vs 10%, p0.001), lower platelet counts (171,000 vs. 209,000, p0.001) and lower hematocrit levels (32% vs. 36%, p0.001). Operative (11% vs. 9%, p = 0.65) or late (2 years; 66 ± 7% vs 66 ± 7%, p = 0.720) mortality; composite incidence of mediastinitis, percutaneous drive-line infection, pocket infection and VAD-related endocarditis (15% vs. 16%, p = 0.79); re-exploration for bleeding (18% vs. 18%, p = 0.99); urgent transplantation for infection (4% vs. 3%, p = 0.99); or need for device exchange (9% vs. 10%, p = 0.16) was not increased after DSC when compared with immediate sternal closure. DSC increased ICU stay (10 vs. 5 days, p = 0.001).DSC was performed most commonly for coagulopathy and/or hemodynamic instability, and patients were older with a greater severity of illness as shown by the higher incidence of right-sided circulatory failure and history of prior sternotomy. Although DSC was associated with longer ICU stay, DSC was not associated with a significantly increased risk of death or infection.

Right ventricular failure (RVF) following implantation of a left ventricular assist system (LVAS) is associated with high morbidity and mortality. 1 - 4 Numerous centers have reported short-term use of the CentriMag® Ventricular Assist System (CVAS) (Levitronix LLC, Waltham, MA) for treatment of cardiogenic shock, decompensated heart failure and right ventricular failure (RVF) following LVAS implantation. 5 - 9 The present report reviews the clinical course of a patient requiring long-term right ventricular support utilizing the CVAS, following a HeartMate® II LVAS (Thoratec Corp. Pleasanton, CA) implantation. Elevated cytotoxic antibody levels complicated the patient’s treatment plan by precluding orthotropic heart transplantation. The CVAS operated for 304 days without mechanical difficulty until replaced with the HeartWare® Ventricular Assist System (HeartWare Inc. Miramar, FL).

Although continuous-flow left ventricular assist device (LVAD) support has become standard therapy, the complexities of device and patient management remain a challenge. In particular, percutaneous site infections (PSI) are a serious complication during the post-implant course. We sought to study the incidence, risk factors, and clinical effect of PSI.Data were obtained from the Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS) Registry. All adult patients who received a primary intracorporeal continuous flow LVAD between June 2006 and September 2010 were included. Descriptive statistics, Kaplan-Meier depictions, and multivariable analysis in the parametric hazard domain were used for statistical analysis.A total of 239 PSIs were documented in 197 of 2,006 recipients (9.8%) of a continuous-flow LVAD. Mean follow-up was 8.1 months. Mean time to development of a PSI was 6.6 months. At 1 year after implant, nearly 19% of continuous-flow LVAD recipients developed a PSI. Multivariate analysis showed younger age (hazard ratio, 1.20; p0.0001) was the only factor predicting a PSI. Continuous-flow LVAD recipients who did not develop a PSI had improved survival (p = 0.004). Twenty-three patients died after development of a PSI. Sepsis was the most common cause of death (26.1%).PSIs occur in approximately 19% of continuous-flow LVAD recipients by 12 months after implant. Young age is the only predictor of PSI. Importantly, development of a PSI adversely affects survival. Efforts to enhance driveline integration and to develop future totally implantable systems are warranted.

Patients requiring biventricular assist device (BiVAD) for mechanical circulatory support (MCS) have substantially worse outcomes than patients requiring left VAD (LVAD) support only. Patient-specific risk factors have yet to be consistently identified in a large, multicenter registry, which may underlie the poorer outcomes for BiVAD patients. The Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS) is a registry of U.S. Food and Drug Administration-approved durable MCS devices used for bridge-to-transplantation, destination therapy, or recovery. The purposes of this study were to 1) identify the underlying pre-implant characteristics of the population requiring BiVAD support that contribute to reduced survival, and 2) identify differences in postoperative outcomes with respect to adverse events compared with patients supported with LVAD alone.From June 2006 to September 2009, 1,646 patients were entered into the INTERMACS database in which adverse events and outcomes were recorded for primary implants with LVAD or BiVAD. Competing outcomes methodology was used to estimate the time-related probability of death, transplant, or recovery. Overall survival for all groups was analyzed with Kaplan-Meier methods and Cox proportional regression analysis.The distribution of primary device implants included 1,440 LVADs and 206 BiVADs. BiVAD patients presented with a lower INTERMACS profile 93% in INTERMACS 1 or 2, compared with 73% for LVAD patients (p0.001). Survival at 6 months was 86% for LVADs and 56% for BiVADs (p.0001). Adverse event rates, expressed as episodes/100 patient-months for the BiVAD group compared with LVAD, were significantly higher for infection (33.2 vs 14.3), bleeding (71.6 vs 15.5), neurologic events (7.9 vs 2.6), and for device failure (4.9 vs 2.0).Patients requiring BiVAD support at the time of durable MCS implant are more critically ill at the time of MCS implant. BiVAD patients experience worse survival than patients supported with LVAD alone and higher rates of serious adverse events. Characteristics of the population present at the time of BiVAD implant likely influence post-implant MCS outcomes.

ObjectiveRight thoracotomy using ventricular fibrillation with cooling has been used for redo mitral valve surgery. This approach avoids the complications of redo sternotomy, such as injury to prior grafts and hemorrhage. As a further refinement, we have used a beating heart technique to further minimize complications while simplifying the operation.MethodsWe reviewed the outcomes of 450 patients who underwent redo mitral valve surgery via a right thoracotomy from 1996 to 2011 at the University of Michigan. Of these, 134 patients underwent redo mitral valve surgery with ventricular fibrillation, and 316 patients underwent beating heart surgery. Although operative eras were consecutive, patients’ age, risk factors, New York Heart Association, and preoperative left ventricular ejection fraction were not significantly different. Core temperature on cardiopulmonary bypass for beating heart surgery was 32°C versus 26°C for ventricular fibrillation.ResultsPatients undergoing beating heart surgery had shorter periods of cardiopulmonary bypass: 81 ± 9 minutes versus 113 ± 36 minutes. Beating heart surgery required less blood products than ventricular fibrillation: 1.65 ± 2 units versus 3.8 ± 5 units packed red blood cells, 0.6 ± 1.2 units versus 1.8 ± 4 units fresh-frozen plasma, and 1.02 ± 4 versus 7.5 ± 17 platelet packs (all P

The continued benefit of United Network of Organ Sharing (UNOS) status 2 transplantation in the modern era has been questioned.We measured deterioration to higher status designations, improvement allowing delisting, and risk of death or delisting as too ill, regardless of subsequent status, from the Scientific Registry of Transplant Recipients database. Extended Cox models were used to assess the relative hazard of status 2 transplantation vs waiting after status 2 listing. The likelihood of transplantation was measured with logistic regression.We analyzed 14,153 candidates listed from 2003 to 2008. Within 1 year of initial listing, deterioration to status 1B occurred frequently (63%), while delisting as too well occurred rarely (2%-7%). Death or delisting as too ill occurred among 27% at 2 years after initial status 2 listing. Mortality at 2 years after status 2 transplantation was 13%. The hazard ratio (HR) after 180 days of status 2 transplantation vs waiting during or after initial status 2 listing was 0.41 (95% confidence interval, 0.31-0.55). The likelihood of transplantation was markedly diminished for women (odds ratio, 0.71; p0.001) and congenital heart disease (odds ratio, 0.24; p0.001). Death or delisting as too ill for women (HR, 1.7; p0.001) and congenital heart disease (HR, 3.2; p0.001) were substantially higher than in other groups.Escalation of UNOS status is common and delisting as too well is uncommon after initial status 2 listing. Despite the decreasing number of transplants provided to status 2 registrants, sub-groups of patients may be at high risk of waiting at status 1A, justifying the continued use of the status 2 designation.

Right ventricular failure (RVF) is a cause of major morbidity and mortality in the left ventricular assist device (LVAD) population. Many LVAD candidates have clinical or subclinical right ventricular (RV) dysfunction, and the perioperative period is fraught with insults that may provoke reactive pulmonary vascular hypertension and acute or chronic development of RVF. Thus, preoperative patient optimization using diuretics, pulmonary vasodilators, and inotropes to reduce RV wall stress and improve contractility is critical. An assessment of the LVAD candidate’s risk for developing postoperative RVF is also key, especially in the destination therapy population for whom good options for long-term RV support currently are lacking. Intraoperatively, various pharmacologic and surgical interventions are available to reduce RVF risk. This review discusses RVF diagnosis and management strategies in subjects undergoing LVAD implantation.

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.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.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.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.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.

The use of implantable ventricular assist devices for the treatment of advanced, decompensated heart failure as a bridge to heart transplantation has experienced considerable evolution over the past decade. Improvements in the management and prevention of serious adverse events, and introduction of new continuous-flow rotary pumps that are smaller, more durable, and associated with fewer serious adverse advents has expanded the use of this therapy to a larger population of patients for bridge to transplant indication. (J Card Surg 2010;25:455-461)

Background— The ubiquitin proteasome system maintains a dynamic equilibrium of proteins and prevents accumulation of damaged and misfolded proteins, yet its role in human cardiac dysfunction is not well understood. The present study evaluated ubiquitin proteasome system function in human heart failure and hypertrophic cardiomyopathy (HCM). Methods and Results— Proteasome function was studied in human nonfailing donor hearts, explanted failing hearts, and myectomy samples from patients with HCM. Proteasome proteolytic activities were markedly reduced in failing and HCM hearts compared with nonfailing hearts ( P P P Conclusions— Proteasome activity in HCM and failing human hearts is impaired in the absence of changes in proteasome protein content or availability of proteolytic active sites. These data provide strong evidence that posttranslational modifications to the proteasome may account for defective protein degradation in human cardiomyopathies.

Background— The Model for End-Stage Liver Disease (MELD) predicts events in cirrhotic subjects undergoing major surgery and may offer similar prognostication in left ventricular assist device candidates with comparable degrees of multisystem dysfunction. Methods and Results— Preoperative MELD scores were calculated for subjects enrolled in the University of Michigan Health System (UMHS) mechanical circulatory support database. Univariate and multiple regression analyses were performed to investigate the ability of patient characteristics, laboratory data (including MELD scores), and hemodynamic measurements to predict total perioperative blood product exposure and operative mortality. The ability of preoperative MELD scores to predict operative mortality was evaluated in subjects enrolled in the Interagency Registry of Mechanically Assisted Circulatory Support (INTERMACS), and results were compared with those from the UMHS cohort. The mean±SD MELD scores for the UMHS (n=211) and INTERMACS (n=324) cohorts were 13.7±6.1 and 15.2±5.8, respectively, with 29 (14%) and 19 (6%) perioperative deaths. In the UMHS cohort, median total perioperative blood product exposure was 74 units (25th and 75th percentiles, 44 and 120 units). Each 5-unit MELD score increase was associated with 15.1±3.8 units (β±SE) of total perioperative blood product exposure. Each 10-unit increase in total perioperative blood product exposure increased the odds of operative death (odds ratio, 1.05; 95% confidence interval, 1.01 to 1.10). Odds ratios, measuring the ability of MELD scores to predict perioperative mortality, were 1.5 (95% confidence interval, 1.1 to 2.0) and 1.5 (95% confidence interval, 1.1 to 2.1) per 5 MELD units for the UMHS and INTERMACS cohorts, respectively. When MELD scores were dichotomized as ≥17 and Conclusion— The MELD score identified left ventricular assist device candidates at high risk for perioperative bleeding and mortality.

Background— We report the first comprehensive analysis of gene expression differences by sex and age in left ventricular samples from 102 patients with dilated cardiomyopathy. Methods and Results— Gene expression data (HG-U133A gene chip, Affymetrix) were analyzed from 30 females and 72 males from 3 separate centers. More than 1800 genes displayed sexual dimorphism in the heart (adjusted P value 140 genes were differentially expressed in the 55 years age group. These genes were highly represented in gene ontology pathways involved in DNA damage. In contrast, zero genes in the male cohort 55 years age group. Conclusions— Gene expression in dilated cardiomyopathy displayed evidence of sexual dimorphism similar to other somatic tissues and age dimorphism within the female cohort.

Background— The objective of this study was to determine the impact of concurrent cardiac procedures (CCP) on patient outcomes after HeartMate II (HMII) left ventricular assist device implantation. Methods and Results— Two hundred eighty-one patients underwent implantation of a HMII as a bridge to transplantation from March 2005 to March 2007. One hundred seventy patients had an HMII implanted only, and 81 patients underwent concurrent cardiac procedures in conjunction with HMII implantation (HMII+CCP). Of these, 47 patients had concurrent valvular procedures, 15 patients had simultaneous closure of patent foramen ovale, and 19 patients had other various cardiac procedures. Patients requiring right ventricular assist device support or noncardiac procedures were excluded. Preoperative characteristics were similar for patients with and without concurrent cardiac procedures. Overall 30-day mortality was 5.8% for the HMII group and 11.3% for the HMII+CCP group. Subgroup analysis demonstrated that simultaneous patent foramen ovale closure was not associated with an increased 30-day mortality rate, but concurrent valvular procedures increased the risk to 8.5%. Patients who underwent an aortic valve procedure had a 30-day mortality rate of 25%, higher than for isolated concurrent mitral (0%) or tricuspid repair (3.3%). Survival at 180 days was 87% for HMII alone and 80% for HMII+CCP. The hazard ratio for concurrent cardiac procedures adjusted for baseline parameters was 1.82 (95% CI, 1.07 to 3.10, P =0.026). Conclusions— There is a low 5.8% operative mortality rate for patients requiring uncomplicated HMII implantation, with no apparent increased risk for concurrent patent foramen ovale closure or mitral or tricuspid repair. However, concurrent aortic valve and other cardiac procedures are associated with significantly decreased perioperative and long-term survival.

Objectives This study sought to assess the impact of continuous flow left ventricular assist devices (LVADs) on functional capacity and heart failure-related quality of life. Background Newer continuous-flow LVAD are smaller and quieter than pulsatile-flow LVADs. Methods Data from advanced heart failure patients enrolled in the HeartMate II LVAD (Thoratec Corporation, Pleasanton, California) bridge to transplantation (BTT) (n = 281) and destination therapy (DT) (n = 374) trials were analyzed. Functional status (New York Heart Association [NYHA] functional class, 6-min walk distance, patient activity scores), and quality of life (Minnesota Living With Heart Failure [MLWHF] and Kansas City Cardiomyopathy Questionnaires [KCCQ]) were collected before and after LVAD implantation. Results Compared with baseline, LVAD patients demonstrated early and sustained improvements in functional status and quality of life. Most patients had NYHA functional class IV symptoms at baseline. Following implant, 82% (BTT) and 80% (DT) of patients at 6 months and 79% (DT) at 24 months improved to NYHA functional class I or II. Mean 6-min walk distance in DT patients was 204 m in patients able to ambulate at baseline, which improved to 350 and 360 m at 6 and 24 months. There were also significant and sustained improvements from baseline in both BTT and DT patients in median MLWHF scores (by 40 and 42 U in DT patients, or 52% and 55%, at 6 and 24 months, respectively), and KCCQ overall summary scores (by 39 and 41 U, or 170% and 178%). Conclusions Use of a continuous flow LVAD in advanced heart failure patients results in clinically relevant improvements in functional capacity and heart failure-related quality of life.

ObjectiveThe aim of this study was to evaluate the incidence, risk factors, and effect on outcomes of right ventricular failure in a large population of patients implanted with continuous-flow left ventricular assist devices.MethodsPatients (n = 484) enrolled in the HeartMate II left ventricular assist device (Thoratec, Pleasanton, Calif) bridge-to-transplantation clinical trial were examined for the occurrence of right ventricular failure. Right ventricular failure was defined as requiring a right ventricular assist device, 14 or more days of inotropic support after implantation, and/or inotropic support starting more than 14 days after implantation. Demographics, along with clinical, laboratory, and hemodynamic data, were compared between patients with and without right ventricular failure, and risk factors were identified.ResultsOverall, 30 (6%) patients receiving left ventricular assist devices required a right ventricular assist device, 35 (7%) required extended inotropes, and 33 (7%) required late inotropes. A significantly greater percentage of patients without right ventricular failure survived to transplantation, recovery, or ongoing device support at 180 days compared with patients with right ventricular failure (89% vs 71%, P < .001). Multivariate analysis revealed that a central venous pressure/pulmonary capillary wedge pressure ratio of greater than 0.63 (odds ratio, 2.3; 95% confidence interval, 1.2–4.3; P = .009), need for preoperative ventilator support (odds ratio, 5.5; 95% confidence interval, 2.3–13.2; P < .001), and blood urea nitrogen level of greater than 39 mg/dL (odds ratio, 2.1; 95% confidence interval, 1.1–4.1; P = .02) were independent predictors of right ventricular failure after left ventricular assist device implantation.ConclusionsThe incidence of right ventricular failure in patients with a HeartMate II ventricular assist device is comparable or less than that of patients with pulsatile-flow devices. Its occurrence is associated with worse outcomes than seen in patients without right ventricular failure. Patients at risk for right ventricular failure might benefit from preoperative optimization of right heart function or planned biventricular support.

Objective Although left ventricular assist devices (LVADs) are associated with excellent outcomes in patients with end-stage heart failure, there are conflicting reports on posttransplant survival in these patients. Furthermore, prior studies with pulsatile LVADs have shown that transplantation, either early ( 6 months) after LVAD implantation, adversely affected post–cardiac transplant survival. We sought to determine factors related to posttransplant survival in patients supported with continuous-flow LVADs. Methods The HeartMate II LVAD (Thoratec Corporation, Pleasanton, Calif) was implanted in 468 patients as a bridge to transplant at 36 centers in a multicenter trial. Patients who underwent transplantation after support were stratified by demographics: gender, age, etiology, body mass index, duration of device support, and by adverse events during support. The median age was 54 years (range 18–73 years); 43% had ischemic etiology, and 18% were women. Survival was determined at the specific intervals of 30 days and 1 year after transplantation. Results Of 468 patients, 250 (53%) underwent cardiac transplant after a median duration of LVAD support of 151 days (longest: 3.2 years), 106 (23%) died, 12 (2.6%) recovered ventricular function and the device was removed, and 100 (21%) were still receiving LVAD support. The overall 30-day and 1-year posttransplant survivals were 97% and 87%. There were no significant differences in survival based on demographic factors or LVAD duration of less than 30 days, 30 to 90 days, 90 to 180 days, and more than 180 days. Patients requiring more than 2 units of packed red blood cells in 24 hours during LVAD support had a statistically significant decreased 1-year survival (82% vs 94%) when compared with patients who did not require more than 2 units of packed red blood cells in 24 hours during LVAD support ( P = .03). There was a trend for slightly lower survival at 1 year in patients with percutaneous lead infections during LVAD support versus no infection (75% vs 89%; P = .07). Conclusions Post–cardiac transplant survival in patients supported with continuous-flow devices such as the HeartMate II LVAD is equivalent to that with conventional transplantation. Furthermore, posttransplant survival is not influenced by the duration of LVAD support. The improved durability and reduced short- and long-term morbidity associated with the HeartMate II LVAD has reduced the need for urgent cardiac transplantation, which may have adversely influenced survival in the pulsatile LVAD era. This information may have significant implications for changing the current United Network for Organ Sharing criteria regarding listing of heart transplant candidates.

Small continuous flow left ventricular assist devices (LVAD) are providing new options for women in advanced heart failure who due to body size limitations were historically excluded from use of large first generation pulsatile devices. We report the experience of women one year after implantation with the new, HeartMate II continuous flow LVAD for bridge to transplantation. Patients (n=279), 24% female (F), 76% male (M) in NYHA Class IV heart failure, LV ejection fraction 16±7% (F), 16±6% (M), mostly inotrope dependent and about half on intraaortic balloon pump support (50% F, 43% M), who had been enrolled in the HM II clinical trial for at least 1 year as a bridge to cardiac transplantation at 33 centers were analyzed. Outcomes and causes of death in the first year of support between F and M recipients were determined. The percentage of patients who had undergone transplantation, recovery of the heart with device removal, or continued on HM II support after one year were the same (80%) between M and F. However, the percentage of patients who had received a heart transplant was significantly less for F (38%) than M (53%) (p2 for M. Kaplan Meier survival at one year was similar for females (74%) and males (76%). The smaller, more durable HM II rotary LVAD may be especially advantageous to women with advanced HF as a bridge to cardiac transplantation, because of significantly smaller BSA and need for extended duration of mechanical support due to longer wait times for suitable organ donors. Outcomes at one-year

Background The current classification of patients with New York Heart Association Class IV symptoms does not offer adequate description to allow optimal selection of patients for the current options of medical and pacing therapies, cardiac transplantation and mechanical circulatory support. Methods Seven clinical profiles and an arrhythmia modifier were developed and implemented into the first year of data collection for the Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS). The INTERMACS Coordinators' Council provided ongoing feedback regarding the characterization of patients receiving implantable devices. Results The definition of 7 clinical profiles revealed that 80% of current devices are being used in the 2 profiles with the highest levels of clinical compromise. The INTERMACS Coordinators' Council helped to identify gaps in the characterization of hospitalized patients on temporary assist devices and of homebound patients with resting symptoms, which has led to revised definitions of Profile 3 and 4 and the addition of 2 new modifiers, for temporary circulatory support devices in the hospital, and for frequent rehospitalization of patients at home. Conclusions Patients considered for mechanical circulatory support can now be classified using the 7 profiles plus 3 modifiers developed through INTERMACS. Further understanding these profiles and their impact on outcome should help to better select patients and therapies in the advanced stages of disease.

This article highlights trends in heart and lung transplantation between 1997 and 2006, drawing on data from the OPTN and SRTR. The total number of candidates actively awaiting heart transplantation declined by 45% over the last decade, dropping from 2414 patients in 1997 to 1327 patients in 2006. The overall death rates among patients awaiting heart transplantation declined over the same period. The distribution of recipients among the different status groups at the time of heart transplantation changed little between the inception of the new classification system in 1999 and 2005. Deaths in the first year after heart transplantation have steadily decreased. At the end of 2006, 2885 candidates were awaiting a lung transplant, up 10% from the 1997 count. The median time-to-transplant for listed patients decreased by 87% over the decade, dropping from 1053 days in 1997 to 132 days in 2006. Selection for listing and transplantation has shifted toward more urgent patients since the May 2005 implementation of a new lung allocation system based on survival benefit and urgency rather than waiting time. Only 31 heart-lung transplants were performed in 2006, down from a high of 62 in 1997.

Background There are limited reports describing multiple-time redo mitral valve surgery using a left thoracotomy approach and on-pump beating heart technique. Methods A retrospective review of medical records for 16 patients from March 2002 to June 2007 was performed. Results Mean age was 54 ± 17 (mean ± SD) years (8 males). Preoperative mitral valve regurgitation was 3.6 ± 0.6 in 14, and 2 had severe mitral valve stenosis. New York Heart Association symptom class was 2.9 ± 1.0 and ejection fraction was 0.4 ± 0.15 (range, 0.2 to 0.6). Previous cardiac operations were performed twice in 14 and three times in 2 patients with an interval of 4.8 ± 5.5 years since the last. The procedures included repair (5), replacement (8), and re-replacement (3). All were performed through a fifth intercostal space, left posterolateral thoracotomy with the heart beating on cardiopulmonary bypass (32 to 37°C). Left femoral artery or descending thoracic aorta inflow and left femoral vein or left main pulmonary artery venous drainage with vacuum assist were used. Operation time was 221 ± 51 minutes and cardiopulmonary bypass time was 71 ± 27 minutes. Postoperative ventilation time was 10.0 ± 7.7 hours, intensive care unit stay was 2.9 ± 1.9 days, and hospital stay was 6.2 ± 2.4 days. There were two 30-day mortalities and two died late with a follow-up of 30 ± 22 months. Conclusions Left thoracotomy using the on-pump beating heart technique is safe, effective, and should be considered for multiple-time redo mitral valve surgery.

Background: The HeartMate (HM) II continuous flow rotary pump represents a new generation of implantable left ventricular assist device (LVAD) that has recently completed clinical evaluation in an FDA-approved study for bridge to transplantation (BTT). Through a continued access protocol (CAP), an additional cohort of patients has undergone implantation of the HMI II device. We report on a comparative analysis of outcomes from both the primary and CAP cohorts. Methods: In a prospective, multi-center study, 297 patients with refractory heart failure and on intravenous inotrope therapy underwent implantation of the HM II to evaluate safety and efficacy as a BTT (n=133 patients-primary study cohort; n=164 patients-CAP; 61 patients in the CAP cohort completed 6 mo followup). Results: Baseline demographics, hemodynamics, renal and hepatic function were not significant between groups (Table 1 ). Number of patients with positive outcomes at 6 mo (transplant, cardiac recovery, alive on LVAD) were similar between cohorts (79% vs 80%). HM II therapy improved 6 minute walk distance at 3 month followup (by 250±232 m vs 226±180 m), and quality of life (Minnesota Living with Heart Failure; by 37% vs. 41%) to similar degrees for each cohort. The incidence of significant adverse events (pump replacements, 5 vs. 1; postoperative bleeding requiring surgery, 31% vs 23%; ischemic and hemorrhagic stroke, 8.0% vs 9.8%; need for RVAD, 4% vs 8%) were not significant between groups. Conclusions: Outcomes from patients implanted with the HMII device during CAP were similar to outcomes of patients implanted in the primary cohort. These analyses validate the original findings regarding efficacy and risk profile of the HM II continuous flow LVAD in this patient population as a BTT. table 1

A b s t r ac t Background The use of left ventricular assist devices is an accepted therapy for patients with refractory heart failure, but current pulsatile volume-displacement devices have limitations (including large pump size and limited long-term mechanical durability) that have reduced widespread adoption of this technology. Continuous-flow pumps are newer types of left ventricular assist devices developed to overcome some of these limitations. Methods In a prospective, multicenter study without a concurrent control group, 133 patients with end-stage heart failure who were on a waiting list for heart transplantation underwent implantation of a continuous-flow pump. The principal outcomes were the proportions of patients who, at 180 days, had undergone transplantation, had cardiac recovery, or had ongoing mechanical support while remaining eligible for transplantation. We also assessed functional status and quality of life. Results The principal outcomes occurred in 100 patients (75%). The median duration of support was 126 days (range, 1 to 600). The survival rate during support was 75% at 6 months and 68% at 12 months. At 3 months, therapy was associated with significant improvement in functional status (according to the New York Heart Association class and results of a 6-minute walk test) and in quality of life (according to the Minnesota Living with Heart Failure and Kansas City Cardiomyopathy questionnaires). Major adverse events included postoperative bleeding, stroke, right heart failure, and percutaneous lead infection. Pump thrombosis occurred in two patients. Conclusions A continuous-flow left ventricular assist device can provide effective hemodynamic support for a period of at least 6 months in patients awaiting heart transplantation, with improved functional status and quality of life. (ClinicalTrials.gov number, NCT00121472.)

Predicting end-of-life for left ventricular assist devices is important to determine timing of device removal. A retrospective analysis was performed on 46 patients undergoing implantation of the latest HeartMate XVE from July 1, 2003, through March 31, 2006. Devices were assessed by analysis of motor current waveforms and quantification of the titanium or copper particles within dust localized to the driveline vent filter by optical, polarized light, scanning electron microscopy, and energy dispersive x-ray spectroscopy. Assessments were performed monthly for patients supportedor =330 days or for unexpected device alarms. Thirty-one (67%) patients were supported for330 days and 15 (33%) were supported foror =330 days. No malfunctions occurred in patients supported330 days. For patients supportedor =330 days, five had abnormal current waveforms or copper and titanium dust localized to the vent filter. One underwent urgent transplantation, three underwent device replacement (one death; two ongoing), and one is with ongoing support. Of the remaining 10 patients, seven underwent transplantation; two remain on device; and one died while on left ventricular assist device support. There were no unexpected device failures. Bearing wear of the HeartMate XVE is predictable by analysis of current waveforms or titanium and copper dust within the vent filter.

Background— Myocardial recovery after left ventricular assist device (LVAD) support has been reported. The LVAD Working Group Recovery Study was a prospective multicenter trial to assess the incidence of myocardial recovery in patients bridged to cardiac transplantation. Methods and Results— After LVAD implantation, patients were evaluated with the use of rest echocardiograms with partial LVAD support and cardiopulmonary exercise testing. Dobutamine echocardiography with hemodynamic measurements was performed in those patients with left ventricular ejection fraction >40% during resting studies. Histological analysis was performed on myocardial samples taken at LVAD implantation and explantation. Sixty-seven LVAD patients with heart failure participated in the study. After 30 days, significant improvement occurred in left ventricular ejection fraction (17±7% versus 34±12%; P P P 40% with partial device support. Left ventricular ejection fraction decreased over time to pre-LVAD measurement by 120 days. Peak V̇ o 2 improved with mechanical support (13.7±4.2 versus 18.9±5.5 mL/kg per minute, 30 versus 120 days; P Conclusions— Cardiac function improves significantly after device implantation. Although cellular recovery and improvement in ventricular function are observed, the degree of clinical recovery is insufficient for device explantation in most patients with chronic heart failure.

A cardiac pseudosarcomatous fibromyxoid tumor (PFT) is described in a previously healthy 35-year-old man, together with a review of the literature. Pseudosarcomatous fibromyxoid tumor is within the spectrum of inflammatory (myofibroblastic) pseudotumors. It has previously been described predominantly within the genitourinary tract and respiratory tract. Inflammatory pseudotumor is rare as a cardiac tumor, and cardiac PFT is not previously reported. No recurrence or metastatic disease has been reported after resection of PFTs elsewhere in the body, and this tumor seems to have a benign clinical course.

Implantable left ventricular assist devices (LVADs) have demonstrated clinical success in both the bridge-to-transplantation and destination-therapy patient populations; however, infection remains one of the most common causes of mortality during mechanical circulatory support. Thus, serious LVAD infections may negate the benefits of LVAD implantation, resulting in decreased quality of life, increased morbidity and mortality, and increased costs associated with implantation. Prevention of device-related infection is crucial to the cost-effective use of mechanical circulatory support devices. Therefore, adherence to evidence-based infection control and prevention guidelines, meticulous surgical technique and optimal postoperative surgical site care form the foundation for LVAD associated infection prevention.

Successful autologous skeletal myoblast transplantation into infarcted myocardium in a variety of animal models has demonstrated improvement in cardiac function. We evaluated the safety and feasibility of transplanting autologous myoblasts into infarcted myocardium of patients undergoing concurrent coronary artery bypass grafting (CABG) or left ventricular assist device implantation (LVAD). In addition, we sought to gain preliminary information on graft survival and any potential improvement of cardiac function. Eighteen patients with a history of ischemic cardiomyopathy participated in a phase I, nonrandomized, multicenter pilot study of autologous skeletal myoblast transplantation concurrent with CABG or LVAD implantation. Twelve patients with a history of previous myocardial infarction (MI) and a left ventricular ejection of less than 30% were enrolled in the CABG arm. In a second arm, six patients underwent LVAD implantation as a bridge to heart transplantation and were required to donate their heart for testing at the time of heart transplant. Myoblasts were successfully transplanted in all patients without any acute injection-related complications or significant long-term unexpected adverse events. Follow-up PET scans showed new areas of viability within the infarct scar in CABG patients. Echocardiography measured an average improvement in left ventricular ejection fraction (LVEF) from 25% to 34%. Histological evaluation in four out of five patients who underwent heart transplantation documented survival and engraftment of the skeletal myoblasts within the infarcted myocardium. These interim results demonstrate survival, feasibility, and safety of autologous myoblast transplantation and suggest that this modality may offer a potential therapeutic treatment for end-stage heart disease.

Background Anterior leaflet repair continues to pose significant operative challenges, particularly in patients with retracted or "short" anterior leaflets, due to rheumatic or radiation induced mitral valve disease. This often results in abandonment of repair in favor of mitral valve replacement, requiring anticoagulation and altering left ventricular (LV) function and geometry. This study examines our experience of anterior leaflet repair with patch augmentation. Methods Forty-two patients underwent mitral valve repair for a shortened anterior leaflet from 1994 to 2003. Twenty-two patients with a mean age of 53 ± 6 years had radiation valvulitis (XR) whereas 20 patients, age 28 ± 7 years had rheumatic heart disease (RHD). Those patients with XR had a mean New York Heart Association (NYHA) class of 3.2 ± 0.4 and an angina score of 2.1 ± 0.6 compared with a NYHA class 3.8 ± 0.2 and no angina in RHD patients. All patients presented with severe MR. Anterior leaflet augmentation with a gluteraldehyde-treated, autologous pericardial patch and complete annuloplasty ring was used in all patients. Additionally, extensive subvalvar debridement was performed in RHD patients. Twelve XR patients underwent concomitant CABG with a mean of 2.4 ± 0.8 grafts/patient. Additional surgical procedures included tricuspid valve repair, anterior septal defect, and aortic valve replacement. Mean follow-up was 39 ± 10 months for XR patients and 12 ± 25 months for RHD patients. Results There were two late deaths in XR patients from underlying malignancies and no deaths in RHD patients. Two RHD patients required reoperation for recurrent mitral regurgitation at 3 and 20 months. All patients demonstrated clinical improvements (NYHA I-II) following repair. No mitral stenosis was induced. Conclusions Despite anterior leaflet shortening from XR or rheumatic alterations, opportunity still exists for gratifying mitral valve repair. By utilizing anterior leaflet patch augmentation, concomitantly with ring annuloplasty, anticoagulation is avoided, LV geometry is preserved, and follow-up reveals excellent functional improvement.

Roseomonasspecies have been increasingly noted as causes of human infection. We present what we believe is the first case of left ventricular assist device (LVAD) infection secondary toRoseomonas. The clinical characteristics ofRoseomonasinfection and the pertinent features of LVAD infection are reviewed.

The donor shortage makes cardiac transplantation a less than ideal treatment for end-stage heart failure. The utility of the left ventricular assist device (LVAD) as a permanent form of circulatory support has recently been established in the REMATCH (Randomized Evaluation of Mechanical Assistance for the Treatment of Congestive Heart Failure) trial. In this report, we describe the surgical management of LVAD patients in REMATCH and their short-term outcomes. Between 1998 and 2001, 129 patients with end-stage heart failure, who were excluded from consideration for transplantation, were enrolled in the REMATCH clinical trial. Patients were randomized to two treatment arms: optimal medical management or HeartMate vented electric LVAD implantation. The primary end point of the study was death from any cause. Secondary end points included the incidence of serious adverse events, the duration of hospitalization, quality of life, and functional status. Sixty-eight patients received an LVAD, 55 (81%) of whom survived for longer than 1 month. The median intensive care unit and hospital lengths of stay (LOS) for those that survived at least 1 month were 15 and 34 days, respectively. Sixty-seven (99%) patients had a serious adverse event. The rates of perioperative bleeding, late bleeding, right heart failure, and sepsis were 0.42, 0.53, 0.15, and 0.53 events/patient-year, respectively. Factors predictive of a longer LOS for the implant hospitalization included sepsis, age, and late bleeding (p < 0.0001). The patients' New York Heart Association functional class improved significantly at 1 month compared with base line (p < 0.001). Functional class improved in LVAD-supported patients despite a high adverse event rate. Most adverse events occurred within 30 days of device implantation. Sepsis, age, and late bleeding were the major determinants of LOS.

There are currently several safe and effective options to provide temporary MCS for patients presenting with cardiogenic shock or refractory heart failure. Newer device designs are currently being developed that will increase the options available to patients. Due to the technological advancements, it will be difficult to predict what devices will ultimately prove to be the most efficacious. It is likely that a variety of devices will be necessary, depending on clinical circumstances and patient characteristics.

We report histological analysis of hearts from patients with end-stage heart disease who were transplanted with autologous skeletal myoblasts concurrent with left ventricular assist device (LVAD) implantation.Autologous skeletal myoblast transplantation is under investigation as a means to repair infarcted myocardium. To date, there is only indirect evidence to suggest survival of skeletal muscle in humans.Five patients (all male; median age 60 years) with ischemic cardiomyopathy, refractory heart failure, and listed for heart transplantation underwent muscle biopsy from the quadriceps muscle. The muscle specimen was shipped to a cell isolation facility where myoblasts were isolated and grown. Patients received a transplant of 300 million cells concomitant with LVAD implantation. Four patients underwent LVAD explant after 68, 91, 141, and 191 days of LVAD support (three transplant, one LVAD death), respectively. One patient remains alive on LVAD support awaiting heart transplantation.Skeletal muscle cell survival and differentiation into mature myofibers were directly demonstrated in scarred myocardium from three of the four explanted hearts using an antibody against skeletal muscle-specific myosin heavy chain. An increase in small vessel formation was observed in one of three patients at the site of surviving myotubes, but not in adjacent tissue devoid of engrafted cells.These findings represent demonstration of autologous myoblast cell survival in human heart. The implanted skeletal myoblasts formed viable grafts in heavily scarred human myocardial tissue. These results establish the feasibility of myoblast transplants for myocardial repair in humans.

Pravastatin and simvastatin prolong survival and reduce transplant-related coronary vasculopathy, although low-density lipoprotein (LDL) lowering with these agents is only modest. The objective of this study was to assess the safety of moderate dose atorvastatin and its efficacy when prior treatment with another statin had failed to lower LDL to100 mg/dl.Data from 185 patients were retrospectively evaluated for adverse events, duration of exposure (person-days), and the mean atorvastatin dose exposure. Changes in lipid parameters, and prednisone and cyclosporine doses were determined.48 patients received atorvastatin for 24,240 person-days at a mean dose exposure of 21 +/- 10 mg. Rhabdomyolysis, myositis, myalgias, and hepatotoxicity occurred in 0, 2, 2, and 0 patients, respectively. All events occurred at the 10-mg dose, within the first 3 months, and were rapidly reversible with atorvastatin discontinuation.Thirty-four patients evaluable for efficacy analyses had a pre-atorvastatin LDL of 145 +/- 38 mg/dl on the following statins: pravastatin (n = 30, 40 +/- 0mg), fluvastatin (n = 3, 33 +/- 12 mg), simvastatin (n = 1, 40 mg). After atorvastatin (21 +/- 9 mg/day) for 133 +/- 67 days, LDL was reduced to 97 +/- 24 mg/dl (relative reduction 31 +/- 20%, p0.0001). At the end of the observation period (418 +/- 229 days, atorvastatin final dose 24 +/- 14 mg/day), LDL was further decreased to 88 +/- 23 mg (relative reduction 37 +/- 17%, p0.0001).Atorvastatin, when used at moderate doses and with close biochemical and clinical monitoring, appears to be safe and is effective in aggressively lowering LDL in heart transplant recipients when treatment with other statins has failed to achieve LDL goals.

Background . Extracorporeal life support (ECLS) is an effective technique for providing emergent circulatory assistance, and may represent a life-saving option in patients who might not initially be considered a candidate for other forms of circulatory support (extracorporeal or implantable left ventricular assist device [LVAD]). In the setting of cardiac arrest, ECLS represents the only viable method of initiating circulatory support. However, ECLS has a number of disadvantages that include high complication rates (eg, stroke, bleeding) and a limited duration of potential support, which have prevented its widespread acceptance, particularly in the adult population. With the increased successful application of long-term implantable LVADs as a bridge to transplant, the major limitation of ECLS could be overcome by bridging patients to a long-term implantable LVAD ("bridge to bridge"), thereby reducing the reluctance to utilize ECLS when indicated. After acquisition of the HeartMate LVAD (Thermo Cardiosystems, Inc, Woburn, MA) we investigated the use of ECLS as a bridge to an implantable LVAD and subsequent transplantation in selected high-risk patients. Methods and Results . From Oct 1, 1996 to Sept 30, 2000, 33 adult patients presenting with cardiac arrest or severe hemodynamic instability were placed on ECLS for the bridge to bridge indication. Of the 33 patients, 10 patients survived to LVAD implant, 1 was bridged directly to transplant, 5 weaned from ECLS, and 16 died on ECLS. Overall, 12 patients survived to discharge. One-year actuarial survival from the initiation of ECLS was 36%. One-year actuarial survival from the time of LVAD implant, conditional on surviving ECLS, was 80%. Conclusions . The 1-year survival of adult patients placed on ECLS and who subsequently survived to an implantable LVAD was favorable. These data support a strategy of ECLS to implantable LVAD bridge to heart transplant in adult patients who are in need of circulatory support and who are not initially candidates for other forms of mechanical support. The favorable results of this strategy support utilization of ECLS even in situations where myocardial recovery is thought to be unlikely.

Background . Extracorporeal life support (ECLS) is an effective technique for providing emergent circulatory assistance. However, its use in adult patients is associated with poor survival when myocardial function fails to recover. Due to the prolonged waiting times for heart transplantation, ECLS as a bridge to transplant is associated with poor survival. In addition, ECLS has been reported to be a significant risk factor for death after bridging to an implantable left ventricular assist device (LVAD). After acquisition of the HeartMate LVAD (Thermo Cardiosystems, Inc) in October 1996, we began using ECLS as a bridge to an implantable LVAD and subsequently transplantation in selected high-risk patients. Methods . From October 1, 1996 to December 1, 1999, 60 adult patients presenting with cardiogenic shock were evaluated for circulatory assistance. Results . Twenty-five patients (group 1) with cardiac arrest or severe hemodynamic instability and multiorgan failure were placed on ECLS. Eight patients survived to LVAD implant, 1 was bridged directly to transplant, and 4 weaned from ECLS. Nine patients in group 1 survived to discharge. Thirty patients (group 2) underwent LVAD implant without ECLS. Twenty-three were bridged to transplant, with 22 surviving to discharge. Five patients (group 3) were placed on extracorporeal ventricular assist with 3 bridged to transplant and all surviving to discharge. One-year actuarial survival from the initiation of circulatory support was 36% (group 1), 73% (group 2), and 60% (group 3). One-year actuarial survival from the time of LVAD implant in group 1, conditional on surviving ECLS, was 75% ( p = NS compared with group 2). Conclusions . In selected high-risk patients, LVAD survival after initial ECLS was not different from survival after LVAD support alone. An initial period of resuscitation with ECLS is an effective strategy to salvage patients with cardiac arrest or extreme hemodynamic instability and multiorgan injury.

Objective: Severe mitral regurgitation is a frequent complication of end-stage cardiomyopathy that contributes to heart failure and predicts a poor survival. We studied the intermediate-term outcome of mitral reconstruction in 48 patients who had cardiomyopathy with severe mitral regurgitation and were operated on between June 1993 and June 1997. Methods: Ages ranged from 33 to 79 years (63 ± 6 years) with left ventricular ejection fractions of 8% to 25% (16% ± 3%). All patients were receiving maximal drug therapy and were in New York Heart Association class III-IV with severe, refractory 4+ mitral regurgitation. Operatively, all 48 had undersized flexible annuloplasty rings inserted, 7 had coronary bypass grafts for incidental disease, 11 had prior bypass grafts, and 11 also had tricuspid valve repair. Results: One operative death occurred as a result of right ventricular failure. Postoperative transesophageal echocardiography revealed mild mitral regurgitation in 7 patients and no mitral regurgitation in 41. There were 10 late deaths, 2 to 47 months after mitral reconstruction. The 1- and 2-year actuarial survivals have been 82% and 71%. At a mean follow-up of 22 months, the number of hospitalizations for heart failure has decreased, and 1 patient has had heart transplantation. Significantly, New York Heart Association class improved from 3.9 ± 0.3 before the operation to 2.0 ± 0.6 after the operation. Twenty-four months after the operation, left ventricular volume and sphericity have decreased, whereas ejection fraction and cardiac output have increased. Conclusion: Whether this favorable modification of left ventricular function and geometry will persist remains unknown. However, mitral repair for cardiomyopathy with mitral regurgitation allows new strategies for these patients. (J Thorac Cardiovasc Surg 1998;115:381-8)

The shortage of donors is responsible for the majority of patients dying while waiting for transplantation. To rescue these critically ill patients, a wide variety of devices have been proposed for circulatory assistance as bridge to heart transplantation [1,2]. Prolonged bridging is often necessary, because of donor scarcity and because of the need to allow complete patient recovery before transplantation.

Atrial fibrillation occurs commonly after open-heart surgery and may delay hospital discharge. The purpose of this study was to assess the use of preoperative amiodarone as prophylaxis against atrial fibrillation after cardiac surgery.In this double-blind, randomized study, 124 patients were given either oral amiodarone (64 patients) or placebo (60 patients) for a minimum of seven days before elective cardiac surgery. Therapy consisted of 600 mg of amiodarone per day for seven days, then 200 mg per day until the day of discharge from the hospital. The mean (+/-SD) preoperative total dose of amiodarone was 4.8+/-0.96 g over a period of 13+/-7 days.Postoperative atrial fibrillation occurred in 16 of the 64 patients in the amiodarone group (25 percent) and 32 of the 60 patients in the placebo group (53 percent) (P=0.003). Patients in the amiodarone group were hospitalized for significantly fewer days than were patients in the placebo group (6.5+/-2.6 vs. 7.9+/-4.3 days, P=0.04). Nonfatal postoperative complications occurred in eight amiodarone-treated patients (12 percent) and in six patients receiving placebo (10 percent, P=0.78). Fatal postoperative complications occurred in three patients who received amiodarone (5 percent) and in two who received placebo (3 percent, P= 1.00). Total hospitalization costs were significantly less for the amiodarone group than for the placebo group ($18,375+/-$13,863 vs. $26,491+/-$23,837, P=0.03).Preoperative oral amiodarone in patients undergoing complex cardiac surgery is well tolerated and significantly reduces the incidence of postoperative atrial fibrillation and the duration and cost of hospitalization.