Impact of surgical ventricular reconstruction on sphericity index in patients with ischaemic cardiomyopathy: follow-up from the STICH trial

AIMS

We sought to evaluate associations between baseline sphericity index (SI) and clinical outcome, and changes in SI after coronary artery bypass graft (CABG) surgery with or without surgical ventricular reconstruction (SVR) in ischaemic cardiomyopathy patients enrolled in the SVR study (Hypothesis 2) of the Surgical Treatment for Ischemic Heart Failure (STICH) trial.

METHODS AND RESULTS

Among 1000 patients in the STICH SVR study, we evaluated 546 patients (255 randomized to CABG alone and 291 to CABG + SVR) whose baseline SI values were available. SI was not significantly different between treatment groups at baseline. After 4 months, SI had increased in the CABG + SVR group, but was unchanged in the CABG alone group (0.69 ± 0.10 to 0.77 ± 0.12 vs. 0.67 ± 0.07 to 0.66 ± 0.09, respectively; P < 0.001). SI did not significantly change from 4 months to 2 years in either group. Although LV end-systolic volume and EF improved significantly more in the CABG + SVR group compared with CABG alone, the severity of mitral regurgitation significantly improved only in the CABG alone group, and the estimated LV filling pressure (E/A ratio) increased only in the CABG + SVR group. Higher baseline SI was associated with worse survival after surgery (hazard ratio 1.21, 95% confidence interval 1.02 - 1.43; P = 0.026). Survival was not significantly different by treatment strategy.

CONCLUSION

Although SVR was designed to improve LV geometry, SI worsened after SVR despite improved LVEF and smaller LV volume. Survival was significantly better in patients with lower SI regardless of treatment strategy.

VAD therapy 20/20: moving beyond the myopic view of a nascent therapy

The past five years have seen remarkable growth in the use of durable, continuous flow left ventricular assist devices (LVAD) with associated improvements in mortality, quality of life, functionality and end-organ function. To sustain the growth of this important therapy, the LVAD community must now address key issues focused around the costs of LVAD care, refined patient selection, and reducing complications associated with this therapy. In this perspective piece, we discuss many of these issues.

Improved early survival with a nonsternotomy approach for continuous-flow left ventricular assist device replacement

BACKGROUND

Even in the modern era of continuous-flow left ventricular assist devices (CF LVADs), device replacement may be required. Nonsternotomy (NS) approaches are being used more commonly for replacement procedures. Outcomes after this less invasive approach compared with those after a reoperative sternotomy (RS) have not been extensively studied. Furthermore, the clinical impact of concurrent cardiac procedures during device replacement has not been examined.

METHODS

From 2005 to 2013, all consecutive implantable LVAD procedures were reviewed, and those using CF devices as both the initial and replacement device were identified. These CF LVAD replacement procedures were divided into those using an RS and those using an NS approach. Periprocedural morbidity and mortality were compared between the groups.

RESULTS

A total of 42 CF LVAD replacements were performed in 39 patients, with 20 using an RS approach and 22 using an NS approach. Eleven of the 20 replacement procedures performed by RS included a concurrent cardiac procedure. Relative to the RS cohort, the NS approach was associated with shorter cardiopulmonary bypass time, reduced length of mechanical ventilation, decreased transfusion requirements, less inotropic support, decreased incidence of right ventricular (RV) dysfunction, and shorter intensive care unit (ICU) and overall hospital stays. An NS approach was also associated with improved 30- and 90-day survival (100% versus 79.0% in the RS group; p = 0.048). RS replacement procedures appeared to be associated with increased morbidity, regardless of whether they included concurrent cardiac procedures.

CONCLUSIONS

Patients who did not require an RS approach and who underwent CF LVAD replacement through an NS approach had improved survival and reduced morbidity compared with those who required an RS.

Characteristics and outcomes of patients with heart failure and discordant findings by right-sided heart catheterization and cardiopulmonary exercise testing

There are limited data integrating findings on right-sided cardiac catheterization and cardiopulmonary exercise testing in ambulatory patients with heart failure. In this study, 187 outpatients with HF referred to the Duke Medical Center for consideration of advanced HF therapies were retrospectively evaluated. All patients had undergone right-sided cardiac catheterization and cardiopulmonary exercise testing; the median cardiac index (CI) was 2.0 L/min/m2 (interquartile range 1.7 to 2.3), and the median peak oxygen consumption was 11.3 ml/kg/min (interquartile range 9.2 to 13.8). Despite aggressive medical therapy, medical management had failed in 97 patients (52%) at 18 months, defined as left ventricular assist device implantation, cardiac transplantation, or death. After multivariate adjustment, factors associated with failure of optimal medical management included percentage achieved of predicted peak oxygen consumption, low CI (i.e., <2 L/min/m2), left ventricular size, and exercise time. Patients with discordant findings on right-sided cardiac catheterization and cardiopulmonary exercise testing were common, occurring in 88 patients (47%). The most common profile was preserved CI but reduced functional capacity, and these patients remained at high risk for requiring advanced therapies, whereas patients with reduced CIs but preserved exercise capacity were uncommon. In conclusion, low CI was independently associated with higher rates of death, transplantation, and left ventricular assist device implantation in this study. Also, patients with preserved CIs at rest but poor functional capacity, so-called cardiac insufficiency, were commonly encountered and had poor outcomes with medical management.

Phosphoproteomic profiling of human myocardial tissues distinguishes ischemic from non-ischemic end stage heart failure

The molecular differences between ischemic (IF) and non-ischemic (NIF) heart failure are poorly defined. A better understanding of the molecular differences between these two heart failure etiologies may lead to the development of more effective heart failure therapeutics. In this study extensive proteomic and phosphoproteomic profiles of myocardial tissue from patients diagnosed with IF or NIF were assembled and compared. Proteins extracted from left ventricular sections were proteolyzed and phosphopeptides were enriched using titanium dioxide resin. Gel- and label-free nanoscale capillary liquid chromatography coupled to high resolution accuracy mass tandem mass spectrometry allowed for the quantification of 4,436 peptides (corresponding to 450 proteins) and 823 phosphopeptides (corresponding to 400 proteins) from the unenriched and phospho-enriched fractions, respectively. Protein abundance did not distinguish NIF from IF. In contrast, 37 peptides (corresponding to 26 proteins) exhibited a ≥ 2-fold alteration in phosphorylation state (p<0.05) when comparing IF and NIF. The degree of protein phosphorylation at these 37 sites was specifically dependent upon the heart failure etiology examined. Proteins exhibiting phosphorylation alterations were grouped into functional categories: transcriptional activation/RNA processing; cytoskeleton structure/function; molecular chaperones; cell adhesion/signaling; apoptosis; and energetic/metabolism. Phosphoproteomic analysis demonstrated profound post-translational differences in proteins that are involved in multiple cellular processes between different heart failure phenotypes. Understanding the roles these phosphorylation alterations play in the development of NIF and IF has the potential to generate etiology-specific heart failure therapeutics, which could be more effective than current therapeutics in addressing the growing concern of heart failure.

An isolated working heart system for large animal models

Since its introduction in the late 19(th) century, the Langendorff isolated heart perfusion apparatus, and the subsequent development of the working heart model, have been invaluable tools for studying cardiovascular function and disease(1-15). Although the Langendorff heart preparation can be used for any mammalian heart, most studies involving this apparatus use small animal models (e.g., mouse, rat, and rabbit) due to the increased complexity of systems for larger mammals(1,3,11). One major difficulty is ensuring a constant coronary perfusion pressure over a range of different heart sizes - a key component of any experiment utilizing this device(1,11). By replacing the classic hydrostatic afterload column with a centrifugal pump, the Langendorff working heart apparatus described below allows for easy adjustment and tight regulation of perfusion pressures, meaning the same set-up can be used for various species or heart sizes. Furthermore, this configuration can also seamlessly switch between constant pressure or constant flow during reperfusion, depending on the user's preferences. The open nature of this setup, despite making temperature regulation more difficult than other designs, allows for easy collection of effluent and ventricular pressure-volume data.

Central venous pressure after coronary artery bypass surgery: does it predict postoperative mortality or renal failure?

OBJECTIVE

Although hemodynamic monitoring is often performed after coronary artery bypass grafting (CABG), the role of monitoring postoperative central venous pressure (CVP) measurement as a predictor of clinical outcomes is unknown. As such, this study tests the hypothesis that postoperative CVP is predictive of operative mortality or renal failure.

METHODS

This is an observational cohort study of detailed clinical data from 2390 randomly selected patients undergoing high-risk CABG or CABG/valve at 55 hospitals participating in the Society of Thoracic Surgeons' National Cardiac Surgery Database 2004-2005. Eligible patients underwent elective/urgent CABG with an ejection fraction less than 40% or elective/urgent CABG at 65 years or older with diabetes or a glomerular filtration rate less than 60 mL/min per 1.73 m2. The exposure of interest is CVP monitoring in the intensive care unit after adult cardiac surgery. The primary outcome measure was correlation between postoperative CVP and inhospital/30-day mortality and renal failure, assessed as a continuous variable, both unadjusted and after adjusting for important clinical factors using logistic regression modeling.

RESULTS

Mean age was 72 years, 54% of patients had diabetes mellitus, 49% were urgent procedures, and mean cardiopulmonary bypass time was 105 minutes. Patients' CVP 6 hours postoperation was strongly associated with inhospital and 30-day mortality: odds ratio (OR) of 1.5 (95% confidence interval [CI], 1.23-1.87) for every 5-mm Hg increase in CVP; P<.0001. This association remained significant after risk adjustment: adjusted OR of 1.44 (95% CI, 1.10-1.89); P<.01. A model adjusting for cardiac index also revealed increased incidence of mortality or renal failure: adjusted OR of 1.5 (95% CI, 1.28-1.86) for every 5-mm Hg increase in CVP; P<.0001.

CONCLUSIONS

Patients' CVP at 6 hours after CABG surgery was highly predictive of operative mortality or renal failure, independent of cardiac index and other important clinical variables. Future studies will need to assess whether interventions guided by postoperative CVP can improve patient outcomes.

Neurological complications of cardiac surgery

As increasing numbers of elderly people undergo cardiac surgery, neurologists are frequently called upon to assess patients with neurological complications from the procedure. Some complications mandate acute intervention, whereas others need longer term observation and management. A large amount of published literature exists about these complications and guidance on best practice is constantly changing. Similarly, despite technological advances in surgical intervention and modifications in surgical technique to make cardiac procedures safer, these advances often create new avenues for neurological injury. Accordingly, rapid and precise neurological assessment and therapeutic intervention rests on a solid understanding of the evidence base and procedural variables.

Surgical revascularization is associated with maximal survival in patients with ischemic mitral regurgitation: a 20-year experience

BACKGROUND

The optimal treatment for ischemic mitral regurgitation remains actively debated. Our objective was to evaluate the relationship between ischemic mitral regurgitation treatment strategy and survival.

METHODS AND RESULTS

We retrospectively reviewed patients at our institution diagnosed with significant coronary artery disease and moderate or severe ischemic mitral regurgitation from 1990 to 2009, categorized by medical treatment alone, percutaneous coronary intervention, coronary artery bypass grafting (CABG), or CABG plus mitral valve repair or replacement. Kaplan-Meier methods and multivariable Cox proportional hazards analyses were performed to assess the relationship between treatment strategy and survival, with the use of propensity scores to account for nonrandom treatment assignment. A total of 4989 patients were included: medical treatment alone=36%, percutaneous coronary intervention=26%, CABG=33%, and CABG plus mitral valve repair or replacement=5%. Median follow-up was 5.37 years. Compared with medical treatment alone, significantly lower mortality was observed in patients treated with percutaneous coronary intervention (adjusted hazard ratio, 0.83; 95% confidence interval, 0.76-0.92; P=0.0002), CABG (adjusted hazard ratio, 0.56; 95% confidence interval, 0.51-0.62; P<0.0001), and CABG plus mitral valve repair or replacement (adjusted hazard ratio, 0.69; 95% confidence interval, 0.57-0.82; P<0.0001). There was no significant difference in these results based on mitral regurgitation severity.

CONCLUSIONS

Patients with significant coronary artery disease and moderate or severe ischemic mitral regurgitation undergoing CABG alone demonstrated the lowest risk of death. CABG with or without mitral valve surgery was associated with lower mortality than either percutaneous coronary intervention or medical treatment alone.

Trends in the use and outcomes of ventricular assist devices among medicare beneficiaries, 2006 through 2011

OBJECTIVES

This study sought to examine trends in mortality, readmission, and costs among Medicare beneficiaries receiving ventricular assist devices (VADs) and associations between hospital-level procedure volume and outcomes.

BACKGROUND

VADs are an option for patients with advanced heart failure, but temporal changes in outcomes and associations between facility-level volume and outcomes are poorly understood.

METHODS

This is a population-based, retrospective cohort study of all fee-for-service Medicare beneficiaries with heart failure who received an implantable VAD between 2006 and 2011. We used Cox proportional hazards models to examine temporal changes in mortality, readmission, and hospital-level procedure volume.

RESULTS

Among 2,507 patients who received a VAD at 103 centers during the study period, the in-hospital mortality decreased from 30% to 10% (p < 0.001), the 1-year mortality decreased from 42% to 26% (p < 0.001), and the all-cause readmission was frequent (82% and 81%; p = 0.70). After covariate adjustment, in-hospital and 1-year mortality decreased (p < 0.001 for both), but the all-cause readmission did not change (p = 0.82). Hospitals with a low procedure volume had higher risks of in-hospital mortality (risk ratio: 1.72; 95% confidence interval [CI]: 1.28 to 2.33) and 1-year mortality (risk ratio: 1.55; 95% CI: 1.24 to 1.93) than high-volume hospitals. Procedure volume was not associated with risk of readmission. The greatest cost was from the index hospitalization and remained unchanged ($204,020 in 2006 and $201,026 in 2011; p = 0.21).

CONCLUSIONS

Short- and long-term mortality after VAD implantation among Medicare beneficiaries improved, but readmission remained similar over time. A higher volume of VAD implants was associated with lower risk of mortality but not readmission. Costs to Medicare have not changed in recent years.

Unexpected abrupt increase in left ventricular assist device thrombosis

BACKGROUND

We observed an apparent increase in the rate of device thrombosis among patients who received the HeartMate II left ventricular assist device, as compared with preapproval clinical-trial results and initial experience. We investigated the occurrence of pump thrombosis and elevated lactate dehydrogenase (LDH) levels, LDH levels presaging thrombosis (and associated hemolysis), and outcomes of different management strategies in a multi-institutional study.

METHODS

We obtained data from 837 patients at three institutions, where 895 devices were implanted from 2004 through mid-2013; the mean (±SD) age of the patients was 55±14 years. The primary end point was confirmed pump thrombosis. Secondary end points were confirmed and suspected thrombosis, longitudinal LDH levels, and outcomes after pump thrombosis.

RESULTS

A total of 72 pump thromboses were confirmed in 66 patients; an additional 36 thromboses in unique devices were suspected. Starting in approximately March 2011, the occurrence of confirmed pump thrombosis at 3 months after implantation increased from 2.2% (95% confidence interval [CI], 1.5 to 3.4) to 8.4% (95% CI, 5.0 to 13.9) by January 1, 2013. Before March 1, 2011, the median time from implantation to thrombosis was 18.6 months (95% CI, 0.5 to 52.7), and from March 2011 onward, it was 2.7 months (95% CI, 0.0 to 18.6). The occurrence of elevated LDH levels within 3 months after implantation mirrored that of thrombosis. Thrombosis was presaged by LDH levels that more than doubled, from 540 IU per liter to 1490 IU per liter, within the weeks before diagnosis. Thrombosis was managed by heart transplantation in 11 patients (1 patient died 31 days after transplantation) and by pump replacement in 21, with mortality equivalent to that among patients without thrombosis; among 40 thromboses in 40 patients who did not undergo transplantation or pump replacement, actuarial mortality was 48.2% (95% CI, 31.6 to 65.2) in the ensuing 6 months after pump thrombosis.

CONCLUSIONS

The rate of pump thrombosis related to the use of the HeartMate II has been increasing at our centers and is associated with substantial morbidity and mortality.

Risk-adjusted survival after tissue versus mechanical aortic valve replacement: a 23-year assessment

BACKGROUND AND AIM OF THE STUDY

Detailed analyses of risk-adjusted outcomes after mitral valve surgery have documented significant survival decrements with tissue valves at any age. Several recent studies of prosthetic aortic valve replacement (AVR) also have suggested a poorer performance of tissue valves, although analyses have been limited to small matched series. The study aim was to test the hypothesis that AVR with tissue valves is associated with a lower risk-adjusted survival, as compared to mechanical valves.

METHODS

Between 1986 and 2009, primary isolated AVR, with or without coronary artery bypass grafting (CABG), was performed with currently available valve types in 2148 patients (1108 tissue valves, 1040 mechanical). Patients were selected for tissue valves to be used primarily in the elderly. Baseline and operative characteristics were documented prospectively with a consistent variable set over the entire 23-year period. Follow up was obtained with mailed questionnaires, supplemented by National Death Index searches. The average time to death or follow up was seven years, and follow up for survival was 96.2% complete. Risk-adjusted survival characteristics for the two groups were evaluated using a Cox proportional hazards model with stepwise selection of candidate variables.

RESULTS

Differences in baseline characteristics between groups were (tissue versus mechanical): median age 73 versus 61 years; non-elective surgery 32% versus 28%; CABG 45% versus 35%; median ejection fraction 55% versus 55%; renal failure 6% versus 1%; diabetes 18% versus 7% (p<0.01). Unadjusted Kaplan-Meier survival was significantly lower with tissue than mechanical valves; however, after risk adjustment for the adverse profiles of tissue valve patients, no significant difference was observed in survival after tissue or mechanical AVR. Thus, the hypothesis did not hold, and risk-adjusted survival was equivalent, of course qualified by the fact that selection bias was evident.

CONCLUSION

With selection criteria that employed tissue AVR more frequently in elderly patients, tissue and mechanical valves achieved similar survival characteristics across the spectrum of patient risk. Further studies of the relative outcomes of mechanical versus tissue valves across the spectrum of patient age seem indicated.

Impact of donor cardiac arrest on heart transplantation

BACKGROUND

Cardiac transplantation is an effective therapy for patients with end-stage heart failure, but it is still hindered by the lack of donor organs. A history of donor cardiac arrest raises trepidation regarding the possibility of poor post-transplant outcomes. The impact of donor cardiac arrest following successful cardiopulmonary resuscitation on heart transplant outcomes is unknown. Therefore, we sought to evaluate the impact of donor cardiac arrest on orthotropic heart transplantation using the United Network for Organ Sharing database.

METHODS

We performed a secondary longitudinal analysis of all cardiac transplants performed between April 1994 and December 2011 through the United Network for Organ Sharing registry. Multiorgan transplants, repeat transplants, and pediatric recipients were excluded. Survival analyses were performed using Kaplan-Meier methods as well as multivariate adjusted logistic regression and Cox proportional hazard models.

RESULTS

A total of 19,980 patients were analyzed. In 856 cases, the donors had histories of cardiac arrest, and in the remaining 19,124 cases, there was no history of donor cardiac arrest. The unadjusted 1-, 5-, and 10-year actuarial survival rates between the arrest and the nonarrest groups were not significantly different. Multivariate logistic regression demonstrated no difference in survival in the donor arrest group at 30 days, 1 year, or 3 years. Furthermore, the adjusted Cox proportional hazard model for cumulative survival also showed no survival difference between the 2 groups.

CONCLUSION

If standard recipient and donor transplantation criteria are met, a history of donor cardiac arrest should not prohibit the potential consideration of an organ for transplantation.

Intraoperative magnesium administration does not improve neurocognitive function after cardiac surgery

BACKGROUND AND PURPOSE

Neurocognitive decline occurs frequently after cardiac surgery and persists in a significant number of patients. Magnesium is thought to provide neuroprotection by preservation of cellular energy metabolism, blockade of the N-methyl-D-aspartate receptor, diminution of the inflammatory response, and inhibition of platelet activation. We therefore hypothesized that intraoperative magnesium administration would decrease postoperative cognitive impairment.

METHODS

After approval by the Duke University Health System Institutional Review Board, 389 patients undergoing cardiac surgery were enrolled in this prospective, randomized, double-blind, placebo-controlled clinical trial. Subjects were randomized to receive magnesium as a 50 mg/kg bolus followed by another 50 mg/kg infusion for 3 hours or placebo bolus and infusion. Cognitive function was assessed preoperatively and again at 6 weeks postoperatively using a standardized test battery. Mean CD11b fluorescence and percentage of platelets expressing CD62P, which are markers of leukocyte and platelet activation, respectively, were assessed by flow cytometry as a secondary outcome. The effect of magnesium on postoperative cognition was tested using multivariable regression modeling, adjusting for age, years of education, baseline cognition, sex, race, and weight.

RESULTS

Among the 389 allocated subjects (magnesium: n=198; placebo: n=191), the incidence of cognitive deficit in the magnesium group was 44.4% compared with 44.9% in the placebo group (P=0.93). The cognitive change score and platelet and leukocyte activation were also not different between the groups. Multivariable analysis revealed a marginal interaction between treatment group and weight such that heavier subjects receiving magnesium were less likely to have cognitive deficit (P=0.06).

CONCLUSIONS

Magnesium administered intravenously during cardiac surgery does not reduce postoperative cognitive dysfunction.

CLINICAL TRIAL REGISTRATION URL

http://www.clinicaltrials.gov. Unique identifier: NCT00041392.