Impact of post-transplant stroke and subsequent functional independence on outcomes following heart transplantation under the 2018 United States heart allocation system

BACKGROUND

This study evaluates the clinical trends, risk factors, and effects of post-transplant stroke and subsequent functional independence on outcomes following orthotopic heart transplantation under the 2018 heart allocation system.

METHODS

The United Network for Organ Sharing registry was queried to identify adult recipients from October 18, 2018 to December 31, 2021. The cohort was stratified into 2 groups with and without post-transplant stroke. The incidence of post-transplant stroke was compared before and after the allocation policy change. Outcomes included post-transplant survival and complications. Multivariable logistic regression was performed to identify risk factors for post-transplant stroke. Sub-analysis was performed to evaluate the impact of functional independence among recipients with post-transplant stroke.

RESULTS

A total of 9,039 recipients were analyzed in this study. The incidence of post-transplant stroke was higher following the policy change (3.8% vs 3.1%, p = 0.017). Thirty-day (81.4% vs 97.7%) and 1-year (66.4% vs 92.5%) survival rates were substantially lower in the stroke cohort (p < 0.001). The stroke cohort had a higher rate of post-transplant renal failure, longer hospital length of stay, and worse functional status. Multivariable analysis identified extracorporeal membrane oxygenation, durable left ventricular assist device, blood type O, and redo heart transplantation as strong predictors of post-transplant stroke. Preserved functional independence considerably improved 30-day (99.2% vs 61.2%) and 1-year (97.7% vs 47.4%) survival rates among the recipients with post-transplant stroke (p < 0.001).

CONCLUSIONS

There is a higher incidence of post-transplant stroke under the 2018 allocation system, and it is associated with significantly worse post-transplant outcomes. However, post-transplant stroke recipients with preserved functional independence have improved survival, similar to those without post-transplant stroke.

Improved waitlist and comparable post-transplant outcomes in simultaneous heart-kidney transplantation under the 2018 heart allocation system

OBJECTIVE

This study aimed to investigate the clinical trends and the impact of the 2018 heart allocation policy change on both waitlist and post-transplant outcomes in simultaneous heart-kidney transplantation in the United States.

METHODS

The United Network for Organ Sharing registry was queried to compare adult patients before and after the allocation policy change. This study included 2 separate analyses evaluating the waitlist and post-transplant outcomes. Multivariable analyses were performed to determine the 2018 allocation system's risk-adjusted hazards for 1-year waitlist and post-transplant mortality.

RESULTS

The initial analysis investigating the waitlist outcomes included 1779 patients listed for simultaneous heart-kidney transplantation. Of these, 1075 patients (60.4%) were listed after the 2018 allocation policy change. After the policy change, the waitlist outcomes significantly improved with a shorter waitlist time, lower likelihood of de-listing, and higher likelihood of transplantation. In the subsequent analysis investigating the post-transplant outcomes, 1130 simultaneous heart-kidney transplant recipients were included, where 738 patients (65.3%) underwent simultaneous heart-kidney transplantation after the policy change. The 90-day, 6-month, and 1-year post-transplant survival and complication rates were comparable before and after the policy change. Multivariable analyses demonstrated that the 2018 allocation system positively impacted risk-adjusted 1-year waitlist mortality (sub-hazard ratio, 0.66, 95% CI, 0.51-0.85, P < .001), but it did not significantly impact risk-adjusted 1-year post-transplant mortality (hazard ratio, 1.03; 95% CI, 0.72-1.47, P = .876).

CONCLUSIONS

This study demonstrates increased rates of simultaneous heart-kidney transplantation with a shorter waitlist time after the 2018 allocation policy change. Furthermore, there were improved waitlist outcomes and comparable early post-transplant survival after simultaneous heart-kidney transplantation under the 2018 allocation system.

Clinical trends, risk factors, and temporal effects of post-transplant dialysis on outcomes following orthotopic heart transplantation in the 2018 United States heart allocation system

BACKGROUND

This study evaluated the current clinical trends, risk factors, and temporal effects of post-transplant dialysis on outcomes following orthotopic heart transplantation after the 2018 United States adult heart allocation policy change.

METHODS

The United Network for Organ Sharing (UNOS) registry was queried to analyze adult orthotopic heart transplant recipients after the October 18, 2018 heart allocation policy change. The cohort was stratified according to the need for post-transplant de novo dialysis. The primary outcome was survival. Propensity score-matching was performed to compare the outcomes between 2 similar cohorts with and without post-transplant de novo dialysis. The impact of post-transplant dialysis chronicity was evaluated. Multivariable logistic regression was performed to identify risk factors for post-transplant dialysis.

RESULTS

A total of 7,223 patients were included in this study. Out of these, 968 patients (13.4%) developed post-transplant renal failure requiring de novo dialysis. Both 1-year (73.2% vs 94.8%) and 2-year (66.3% vs 90.6%) survival rates were lower in the dialysis cohort (p < 0.001), and the lower survival rates persisted in a propensity-matched comparison. Recipients requiring only temporary post-transplant dialysis had significantly improved 1-year (92.5% vs 71.6%) and 2-year (86.6 % vs 52.2%) survival rates compared to the chronic post-transplant dialysis group (p < 0.001). Multivariable analysis demonstrated low pretransplant estimated glomerular filtration (eGFR) and bridge with extracorporeal membrane oxygenation (ECMO) were strong predictors of post-transplant dialysis.

CONCLUSIONS

This study demonstrates that post-transplant dialysis is associated with significantly increased morbidity and mortality in the new allocation system. Post-transplant survival is affected by the chronicity of post-transplant dialysis. Low pretransplant eGFR and ECMO are strong risk factors for post-transplant dialysis.

Impact of a Medication Optimization Clinic on Heart Failure Hospitalizations

Efforts to optimize guideline-directed medical therapy (GDMT) through team-based care may affect outcomes in patients with heart failure with reduced ejection fraction (HFrEF). This study evaluated the impact of an innovative medication optimization clinic (MOC) on GDMT and outcomes in patients with HFrEF. Patients with HFrEF who are not receiving optimal GDMT are referred to MOC and managed by a team comprised of a nurse practitioner or physician assistant, clinical pharmacist, and HF cardiologist. We retrospectively evaluated the impact of MOC (n = 206) compared with usual care (n = 412) with a 2:1 propensity-matched control group. The primary clinical outcome was the incidence of HF hospitalizations at 3 months after the index visit. Kaplan-Meier cumulative event curves and Cox proportional hazards regression models with adjustment were conducted. A significantly higher proportion of patients in MOC received quadruple therapy (49% vs 4%, p <0.0001), angiotensin receptor neprilysin inhibitor (60% vs 27%, p <0.0001), mineralocorticoid receptor antagonist (59% vs 37%, p <0.0001), and sodium-glucose cotransporter-2 inhibitor (60% vs 10%, p <0.0001). The primary outcome was significantly lower in the MOC versus the control group (log-rank, p = 0.0008). Cox regression showed that patients in the control group were more than threefold more likely to be hospitalized because of HF than those in the MOC group (p = 0.0014). In conclusion, the MOC was associated with improved GDMT and lower risk of HF hospitalizations in patients with HFrEF.

Left ventricular assist device bridging to heart transplantation: Comparison of temporary versus durable support

BACKGROUND

Since the revision of the United States heart allocation system, increasing use of mechanical circulatory support has been observed as a means to support acutely ill patients. We sought to compare outcomes between patients bridged to orthotopic heart transplantation (OHT) with either temporary (t-LVAD) or durable left ventricular assist devises (d-LVAD) under the revised system.

METHODS

The United States Organ Network database was queried to identify all adult OHT recipients who were bridged to transplant with either an isolated t-LVAD or d-LVAD from 10/18/2018 to 9/30/2020. The primary outcome was 1-year post-transplant survival. Predictors of mortality were also modeled, and national trends of LVAD bridging were examined across the study period.

RESULTS

About 1,734 OHT recipients were analyzed, 1,580 (91.1%) bridged with d-LVAD and 154 (8.9%) bridged with t-LVAD. At transplant, the t-LVAD cohort had higher total bilirubin levels and greater prevalence of pre-transplant intravenous inotrope usage and mechanical ventilation. Median waitlist time was also shorter for t-LVAD. At 1 year, there was a non-significant trend of increased survival in the t-LVAD cohort (94.8% vs 90.1%; p = 0.06). After risk adjustment, d-LVAD was associated with a 4-fold hazards for 1-year mortality (hazard ratio 3.96, 95% confidence interval 1.42-11.03; p = 0.009). From 2018 to 2021, t-LVAD bridging increased, though d-LVAD remained a more common bridging strategy.

CONCLUSIONS

Since the 2018 allocation change, there has been a steady increase in t-LVAD usage as a bridge to OHT. Overall, patients bridged with these devices appear to have least equivalent 1-year survival compared to those bridged with d-LVAD.

Recent Changes in Durable Left Ventricular Assist Device Bridging to Heart Transplantation

This study evaluates the impact of the recent United Network for Organ Sharing (UNOS) allocation policy change on outcomes of patients bridged with durable left ventricular assist devices (LVADs) to orthotopic heart transplantation (OHT). Adults bridged to OHT with durable LVADs between 2010 and 2019 were included. Patients were stratified based on the temporal relationship of their OHT to the UNOS policy change on October 18, 2018. The primary outcome was early post-OHT survival. In total, 9,628 OHTs were bridged with durable LVADs, including 701 (7.3%) under the new policy. Of all OHTs performed during the study period, the proportion occurring following durable LVAD bridging decreased from 45% to 34% (p < 0.001). The more recent cohort was higher risk, including more extracorporeal membrane oxygenation bridging (2.6% vs. 0.3%, p < 0.001), more mechanical right ventricular support (9.7% vs. 1.4%, p < 0.001), greater pretransplant ICU admission (22.8% vs. 8.7%, p < 0.001) more need for total functional assistance (62.8% vs. 53.0%, p < 0.001), older donor age (33.3 vs. 31.7 years, p < 0.001), and longer ischemic times (3.38 vs. 3.13 hours, p < 0.001). Despite this, early post-OHT survival was comparable at 30 days (96.1% vs. 96.0%, p = 0.89), 90 days (93.7% vs. 94.0%, p = 0.76), and 6 months (91.0% vs. 93.0%, p = 0.96), findings that persisted after risk-adjustment. In this early analysis, OHT following bridging with durable LVADs is performed less frequently and in higher risk recipients under the new allocation policy. Despite this, short-term posttransplant outcomes appear to be unaffected in this patient cohort in the current era.

Pre-implant left ventricular dimension is not associated with worse outcomes after left ventricular assist device implantation

Background

Left ventricular dimension has the potential to impact clinical outcomes following implantation of left ventricular assist devices (LVAD). We investigated the effect of pre-implant left ventricular end-diastolic diameter (LVEDD) on outcomes following LVAD implantation.

Methods

Patients implanted with a continuous-flow LVAD between 2004 and 2018 at a single institution were included. The primary outcome was death while on LVAD support. Secondary outcomes included adverse event rates such as renal failure requiring dialysis, device thrombosis, and right ventricular failure. The LVEDD measurements were dichotomized using restricted cubic splines and threshold regression. Survival was determined using Kaplan-Meier estimates. Multivariable logistic regression was used to determine risk-adjusted mortality based on LVEDD.

Results

A total of 344 patients underwent implantation of a continuous flow LVAD during the study period. The optimal cut point for LVEDD was 65 mm, with 126 (36.6%) subjects in the <65 mm group and 165 (48.0%) in the >65 mm group. The LVEDD <65 mm group was older, had more females, higher incidence of diabetes, more pre-implant mechanical ventilation, and more admissions for acute myocardial infarctions (all, P<0.05). Importantly, post-implant adverse events were similar between the groups (all, P>0.05). Risk-adjusted survival at 1-year (OR 1.3, 95% CI: 0.6–2.5, P=0.53) was also comparable between the groups. Furthermore, incremental increases in LVEDD when modeled as a continuous variable did not impact overall mortality (OR 0.98, 95% CI: 0.9–1.0, P=0.09).

Conclusions

Preoperative LVEDD was not associated with rates of major morbidities or mortality following LVAD implantation.

The Preimplantation Psychosocial Evaluation and Prediction of Clinical Outcomes During Mechanical Circulatory Support: What Information Is Most Prognostic?

BACKGROUND

Psychosocial evaluations are required for long-term mechanical circulatory support (MCS) candidates, no matter whether MCS will be destination therapy (DT) or a bridge to heart transplantation. Although guidelines specify psychosocial contraindications to MCS, there is no comprehensive examination of which psychosocial evaluation domains are most prognostic for clinical outcomes. We evaluated whether overall psychosocial risk, determined across all psychosocial domains, predicted outcomes, and which specific domains appeared responsible for any effects.

METHODS

A single-site retrospective analysis was performed for adults receiving MCS between April 2004 and December 2017. Using an established rating system, we coded psychosocial evaluations to identify patients at low, moderate, or high overall risk. We similarly determined risk within each of 10 individual psychosocial domains. Multivariable analyses evaluated whether psychosocial risk predicted clinical decisions about MCS use (DT versus bridge), and postimplantation mortality, transplantation, rehospitalization, MCS pump exchange, and standardly defined adverse medical events (AEs).

RESULTS

In 241 MCS recipients, greater overall psychosocial risk increased the likelihood of a DT decision (odds ratio, 1.76; P = 0.017); and postimplantation pump exchange and occurrence of AEs (hazard ratios [HRs] ≥ 1.25; P ≤ 0.042). The individual AEs most strongly predicted were cardiac arrhythmias and device malfunctions (HRs ≥ 1.39; P ≤ 0.032). The specific psychosocial domains predicting at least 1 study outcome were mental health problem severity, poorer medical adherence, and substance use (odds ratios and HRs ≥ 1.32; P ≤ 0.010).

CONCLUSIONS

The psychosocial evaluation predicts not only clinical decisions about MCS use (DT versus bridge) but important postimplantation outcomes. Strategies to address psychosocial risk factors before or soon after implantation may help to reduce postimplantation clinical risks.

Evolving Trends in Adult Heart Transplant With the 2018 Heart Allocation Policy Change

Importance

The US heart allocation policy was changed on October 18, 2018. The association of this change with recipient and donor selection and outcomes remains to be elucidated.

Objective

To evaluate changes in patient characteristics, wait list outcomes, and posttransplant outcomes after the recent allocation policy change in heart transplant.

Design, Setting, and Participants

In this cohort study, all 15 631 adults undergoing heart transplants, excluding multiorgan transplants, in the US as identified by the United Network for Organ Sharing multicenter, national registry were reviewed. Patients were stratified according to prepolicy change (October 1, 2015, to October 1, 2018) and postpolicy change (October 18, 2018 or after). Follow-up data were available through March 31, 2020.

Exposures

Heart transplants after the policy change.

Main Outcomes and Measures

Competing risk regression for wait list outcomes was performed. Posttransplant survival was compared using the Kaplan-Meier method, and risk adjustment was performed using multivariable Cox proportional hazards regression analysis.

Results

In this cohort study, of the 15 631 patients undergoing transplant, 10 671 (mean [SD] age, 53.1 [12.7] years; 7823 [73.3%] male) were wait listed before and 4960 (mean [SD] age, 52.7 [13.0] years; 3610 [72.8%] male) were wait listed after the policy change. Competing risk regression demonstrated reduced likelihood of mortality or deterioration (subhazard ratio [SHR], 0.60; 95% CI, 0.52-0.69; P < .001), increased likelihood of transplant (SHR, 1.38; 95% CI, 1.32-1.45; P < .001), and reduced likelihood of recovery (SHR, 0.54; 95% CI, 0.40-0.73; P < .001) for wait listed patients after the policy change. A total of 6078 patients underwent transplant before and 2801 after the policy change. Notable changes after the policy change included higher frequency of bridging with temporary mechanical circulatory support and lower frequency of bridging with durable left ventricular assist devices. Posttransplant survival was reduced after the policy change (1-year: 92.1% vs 87.5%; log-rank P < .001), a finding that persisted after risk adjustment (HR, 1.29; 95% CI, 1.07-1.55; P = .008).

Conclusions and Relevance

Substantial changes have occurred in adult heart transplant in the US after the policy change in October 2018. Wait list outcomes have improved, although posttransplant survival has decreased. These data confirm findings from earlier preliminary analyses and demonstrate that these trends have persisted to 1-year follow-up, underscoring the importance of continued reevaluation of the new heart allocation policy.

Twenty-year survival following orthotopic heart transplantation in the United States

BACKGROUND

This study evaluated 20-year survival after adult orthotopic heart transplantation (OHT).

METHODS

The United Network of Organ Sharing Registry database was queried to study adult OHT recipients between 1987 and 1998 with over 20-year posttransplant follow-up. The primary and secondary outcomes were 20-year survival and cause of death after OHT, respectively. Multivariable logistic regression was used to identify significant independent predictors of long-term survival, and long-term survival was compared among cohorts stratified by number of predictors using Kaplan Meier survival analysis.

RESULTS

20,658 patients undergoing OHT were included, with a median follow-up of 9.0 (IQR, 3.2-15.4) years. Kaplan-Meier estimates of 10-, 15-, and 20-year survival were 50.2%, 30.1%, and 17.2%, respectively. Median survival was 10.1 (IQR, 3.9-16.9) years. Increasing recipient age (>65 years), increasing donor age (>40 years), increasing recipient body mass index (>30), black race, ischemic cardiomyopathy, and longer cold ischemic time (>4 h) were adversely associated with a 20-year survival. Of these 6 negative predictors, presence of 0 risk factors had the greatest 10-year (59.7%) and 20-year survival (26.2%), with decreasing survival with additional negative predictors. The most common cause of death in 20-year survivors was renal, liver, and/or multisystem organ failure whereas graft failure more greatly impacted earlier mortality.

CONCLUSIONS

This study identifies six negative preoperative predictors of 20-year survival with 20-year survival rates exceeding 25% in the absence of these factors. These data highlight the potential for very long-term survival after OHT in patients with end-stage heart failure and may be useful for patient selection and prognostication.

Nationwide variability in the use of induction immunosuppression for adult heart transplantation

BACKGROUND

Institutional factors have been shown to impact outcomes following orthotopic heart transplantation (OHT). This study evaluated center variability in the utilization of induction therapy for OHT and its implications on clinical outcomes.

METHODS

Adult OHT patients between 2010 and 2018 were identified from the United Network for Organ Sharing registry. Transplant centers were stratified based on their rates of induction therapy utilization. Mixed-effects logistic regression models were created with drug-treated rejection within 1 year as primary endpoint and individual centers as a random parameter. Risk-adjusted Cox regression was used to evaluate patient-level mortality outcomes.

RESULTS

In 17,524 OHTs performed at 100 centers, induction therapy was utilized in 48.6% (n = 8411) with substantial variability between centers (interquartile range, 21.4%-79.1%). There were 36, 30, and 34 centers in the low (<29%), intermediate (29%-66%), and high (>67%) induction utilization terciles groups, respectively. Induction therapy did not account for the observed variability in the treated rejection rate at 1 year among centers after adjusting for donor and recipient factors (p = .20). No differences were observed in postoperative outcomes among induction utilization centers groups (all, p > .05). Furthermore, there was a weak correlation between the percentage of induction therapy utilization at the center-level and recipients found to have moderate (r = .03) or high (r = .04) baseline risks for acute rejection at 1 year.

CONCLUSIONS

This analysis demonstrates that there is substantial variability in the use of induction therapy among OHT centers. In addition, there was a minimal correlation with baseline recipient risk or 1-year rejection rates, suggesting a need for better-standardized practices for induction therapy use in OHT.

Intra-Aortic Balloon Pump Bridging to Heart Transplantation: Impact of the 2018 Allocation Change

BACKGROUND

This study evaluates the impact of the 2018 allocation policy change on outcomes of orthotopic heart transplantation (OHT) in patients bridged with intra-aortic balloon pumps (IABPs).

METHODS

Adult (≥18 years) patients undergoing OHT between 2013 and 2019 who were bridged with an IABP were stratified based on temporal relation to the policy change. Univariate analysis was used to compare baseline characteristics and postoperative outcomes. Multivariate Cox regression analysis was used to estimate risk-adjusted predictors of post-transplant mortality.

RESULTS

A total of 1342 (8.6%) OHT patients were bridged with an IABP during the study period. Rates of bridging with IABP to OHT increased significantly after the policy change (7.0% versus 24.9%, P<0.001). The mean recipient age was 54.1±12.1 years with 981 (73.1%) patients being male. Baseline characteristics were similar between the 2 groups whereas post-policy change patients spent fewer days on the waitlist (15 versus 35 days, P<0.001), had longer ischemic times (3.5 versus 3.0 hours, P<0.001), and received organs from a greater distance (301 versus 105 miles, P<0.001). By multivariable analysis, days on the waitlist (for every 30 days; odds ratio, 1.01 [95% CI, 1.00-1.02], P=0.031) and diabetes mellitus (odds ratio, 1.87 [95% CI, 1.16-3.02], P=0.011) emerged as significant predictors of post-transplant mortality. After the policy change, waitlisted patients requiring IABP support were more likely to survive to transplant (76.4 versus 89.8%, P<0.001).

CONCLUSIONS

IABP utilization has increased over 3-fold since the 2018 policy change with improved waitlist outcomes and comparable post-OHT survival. Thus, bridging patients to OHT with IABPs appears to be an effective strategy in the current era.

Left ventricular assist device implantation in patients with a history of malignancy

BACKGROUND

This study evaluates the impact of a history of malignancy on outcomes of left ventricular assist device (LVAD) implantation.

METHODS

Adult patients with a preimplant history of malignancy who underwent LVAD implantation between 2006 and 2018 were included. The primary outcome was post-LVAD survival.

RESULTS

A total of 250 patients underwent LVAD implant during the study period, including 37 (14.8%) patients with a history of malignancy. Of these 37 patients, five (13.5%) had active malignancy at the time of LVAD implantation, and seven had more than one type of cancer. The median disease-free duration before LVAD was 3.5 years (interquartile range [IQR] 1.0-7.75 years). The most common types of malignancy included urologic (n = 20; 45.5%), skin (n = 7, 15.9%), and leukemia or lymphoma (n = 6; 13.6%). Median follow-up was 244 (IQR, 126-571) days and 313 (IQR 127-738) days for those with and without a history of malignancy, respectively (P = .49). Unadjusted post-LVAD survival was reduced in those with a malignancy history (2-year survival 53.4% vs 66.9%; P = .01), a finding that persisted after risk-adjustment (hazard ratio 1.89, 95% confidence interval, 1.13-3.14; P = .01). Only one (2.7%) patient died post-LVAD from their cancer.

CONCLUSIONS

Although a history of malignancy is associated with reduced survival after LVAD implantation, more than half of the patients are alive at 2 years. This combined with the fact that most do not die from causes directly related to their cancer suggest that LVAD implantation is reasonable to perform in carefully selected patients with a history of malignancy.

Ruptured cerebral mycotic aneurysm in a left ventricular assist device patient with bacteremia

A 50-year-old male with a history of nonischemic dilated cardiomyopathy presented in cardiogenic shock and ultimately underwent durable left ventricular assist device implantation. He recovered well initially but developed persistent bacteremia. His indwelling pacemaker leads were extracted due to evidence of vegetation. Shortly thereafter, around 3 months post-left ventricular assist device, he succumbed to a massive intracranial hemorrhage due to ruptured cerebral mycotic aneurysm. This case highlights the potential importance of brain imaging in left ventricular assist device patients with persistent bacteremia to avoid this likely catastrophic complication.

Sex-Based Heart Transplant Outcomes After Bridging With Centrifugal Left Ventricular Assist Devices

BACKGROUND

Prior studies demonstrated that female sex is associated with an increased mortality after orthotopic heart transplantation (OHT). The impact of sex on OHT outcomes after bridging with newer-generation durable left ventricular assist devices (LVADs) remains unclear.

METHODS

The United Network for Organ Sharing database was queried to study OHT recipients bridged with a newer-generation LVAD (ie, HeartMate III or HeartWare) between 2010 and 2018. The primary outcome was mortality at 30 and 90-days and 1-year. Secondary outcomes included rates of posttransplant complications. Propensity score matching and Cox multivariable analysis were used to assess comorbidity-adjusted sex differences in outcomes.

RESULTS

A total of 3010 patients (76.7% male) bridged with newer-generation LVADs underwent OHT. After adjusting for relevant covariates, both age and heart failure etiology, but not sex, were independent predictors of mortality. In the matched cohorts, sex did not affect posttransplant outcomes, including renal failure, cerebrovascular events, allograft rejection, functional status, or mortality (all P > .05). Survival at 1-year after OHT was 90.5% in males and 92.8% in females (P = .058).

CONCLUSIONS

Among 3010 OHT recipients, matched females bridged with newer-generation HeartWare or HeartMate III LVADs have comparable posttransplant outcomes compared with males. Furthermore, survival at 1-year follow-up was not affected by sex; instead, it was driven by well-established risk factors including increased age, worse preoperative renal function, and heart failure etiology. These data suggest that considerable progress has been made in mitigating sex differences in heart failure outcomes in the modern era.

Outcomes of Pulmonary Arterial Hypertension Are Improved in a Specialty Care Center

BACKGROUND

Pulmonary arterial hypertension (PAH) is characterized by elevated pulmonary arterial pressures and is managed by vasodilator therapies. Current guidelines encourage PAH management in specialty care centers (SCCs), but evidence is sparse regarding improvement in clinical outcomes and correlation to vasodilator use with referral.

RESEARCH QUESTION

Is PAH management at SCCs associated with improved clinical outcomes?

STUDY DESIGNAND METHODS

A single-center, retrospective study was performed at the University of Pittsburgh Medical Center (UPMC; overseeing 40 hospitals). Patients with PAH were identified between 2008 and 2018 and classified into an SCC or non-SCC cohort. Cox proportional hazard modeling was done to compare for all-cause mortality, as was negative binomial regression modeling for hospitalizations. Vasodilator therapy was included to adjust outcomes.

RESULTS

Of 580 patients with PAH at UPMC, 455 (78%) were treated at the SCC, comprising a younger (58.8 vs 64.8 years; P < .001) and more often female (68.4% vs 51.2%; P < .001) population with more comorbidities without differences in race or income. SCC patients demonstrated improved survival (hazard ratio, 0.68; P = .012) and fewer hospitalizations (incidence ratio, 0.54; P < .001), and provided more frequent disease monitoring. Early patient referral to SCC (< 6 months from time of diagnosis) was associated with improved outcomes compared with non-SCC patients. SCC patients were more frequently prescribed vasodilators (P < .001) and carried more diagnostic PAH coding (P < .001). Vasodilators were associated with improved outcomes irrespective of location but without statistical significance when comparing between locations (P > .05).

INTERPRETATION

The UPMC SCC demonstrated improved outcomes in mortality and hospitalizations. The SCC benefit was multifactorial, with more frequent vasodilator therapy and disease monitoring. These findings provide robust evidence for early and regular referral of patients with PAH to SCCs.

Temporary left ventricular assist devices as a bridge to heart transplantation

BACKGROUND

To create equitable access to donor organs for the highest mortality patients, the cardiac transplant allocation system now prioritizes patients with surgically implanted temporary left ventricular assist devices (T-LVADs). The outcomes following a direct bridge from a T-LVAD to orthotopic heart transplant (OHT) are not well delineated.

AIM

This study investigates the T-LVAD waitlist outcomes and compares the posttransplant outcomes in patients bridged to OHT with surgically implanted T-LVADs to patients bridged with durable continuous-flow left ventricular assist devices (CF-LVADs).

METHODS

Adults recorded in the United Network for Organ Sharing registry bridged to OHT with a durable CF-LVAD and T-LVADs, with or without temporary right ventricular assist devices (T-RVADs), between 2010 and 2018 were included. Propensity matching and multivariable Cox regression were utilized to compare outcomes.

RESULTS

Of 504 patients waitlisted with T-LVADs, the majority were transplanted (50%), bridged to CF-LVAD (17%), or recovered (9%). A total of 9047 recipients were bridged to OHT during the study period with 8875 CF-LVADs and 172 T-LVADs. Early survival in propensity-matched T-LVAD ± T-RVAD patients was similar to CF-LVAD ± T-RVAD patients but reduced at a 1-year follow-up. This difference in survival at 1-year follow-up was attributable to significantly reduced survival in patients with combined T-LVAD + T-RVAD support when compared with CF-LVAD, isolated T-LVAD and combined CF-LVAD + T-RVAD support (80% vs 90% vs 90% vs 91%; P = .005).

CONCLUSIONS

This study demonstrates that most patients waitlisted with a T-LVAD are successfully bridged to durable therapy or recover, and those bridged to OHT have acceptable posttransplant outcomes, particularly when T-RVADs are not required.

Pulmonary vascular resistance determines mortality in end-stage renal disease patients with pulmonary hypertension

The multifactorial etiology of pulmonary hypertension (PH) in end-stage renal disease (ESRD) includes patients with and without elevated pulmonary vascular resistance (PVR). We explored the prognostic implication of this distinction by evaluating pretransplant ESRD patients who underwent right heart catheterization and echocardiography. Demographics, clinical data, and test results were analyzed. All-cause mortality data were obtained. Median follow-up was 4 years. Of the 150 patients evaluated, echocardiography identified 99 patients (66%) with estimated pulmonary artery (PA) systolic pressure > 36 mm Hg, which correlated poorly with mortality (HR = 1.28, 95% CI 0.72-2.27, P = .387). Right heart catheterization identified 88 (59%) patients with mean PA pressure ≥ 25 mm Hg. Of these, 70 had PVR ≤ 3 Wood units and 18 had PVR > 3 Wood units. Survival analysis demonstrated a significant prognostic effect of an elevated PVR in patients with high mean PA pressures (HR = 2.26, 95% CI 1.07-4.77, P = .03), while patients with high mean PA pressure and normal PVR had equivalent survival to those with normal PA pressure. Despite the high prevalence of PH in ESRD patients, elevated PVR is uncommon and is a determinant of prognosis in patients with PH. Patients with normal PVR had survival equivalent to those with normal PA pressures.

Impact of four times daily dosing of oral treprostinil on tolerability and daily dose achieved in pulmonary hypertension

Oral treprostinil (TRE) is a prostacylin that is approved for the treatment of patients with pulmonary arterial hypertension (PAH). Dosing is approved for two or three times daily (t.i.d.); however, adverse effects, including gastrointestinal-related symptoms, may limit the ability to reach optimal doses. We report our experience with a four times daily (q.i.d.) regimen of oral TRE for goal-directed therapy of PAH. We describe three patients that were transitioned from infusion or inhaled TRE to oral TRE with initial t.i.d. dosing over a four-day hospital stay. All patients were subsequently further dose-adjusted in the outpatient setting; however, adverse effects limited additional up-titration despite persistent dyspnea. In a carefully monitored outpatient setting, patients were switched from t.i.d. to q.i.d. dosing of oral TRE. All three patients were successfully dosed q.i.d., having achieved a higher total daily dose compared with a t.i.d. dose regimen. Furthermore, patients were able to maintain functional class II symptoms with mitigation of adverse effects using the q.i.d. dose regimen.

Recommendations for the use of oral treprostinil in clinical practice: a Delphi consensus project pulmonary circulation

Oral treprostinil was recently labeled for treatment of pulmonary arterial hypertension. Similar to the period immediately after parenteral treprostinil was approved, there is a significant knowledge gap for practicing physicians who might prescribe oral treprostinil. Despite its oral route of delivery, use of the drug is challenging because of the requirement for careful titration and management of drug-related adverse effects. We aimed to create a consensus document combining available evidence with expert opinion to provide guidance for use of oral treprostinil. Following a methodology commonly used in business and social sciences (the 'Delphi Process'), two investigators from the oral treprostinil (Freedom) studies created a series of statements based on available evidence and the package insert. The set of 'best practice' statements was circulated to nine other Freedom trial investigators. Their comments were incorporated into the document as new line items for further vote and comment. The subsequent document was put to vote line by line (scale of -5 to +5) and a final statement was drafted. Consensus recommendations include initial therapy with 0.125 mg for treatment naÿ patients, three times daily dosing, aggressive use of antidiarrheal medication, and a strong preference for use of the drug in combination with other approved PAH therapies. This process was particularly valuable in providing guidance for the management of adverse events (where essentially no data is available). The Delphi process was useful to codify investigator experience and subsequently develop investigator consensus about practical issues for physicians who may wish to prescribe oral treprostinil.

Oral treprostinil for the treatment of pulmonary arterial hypertension in patients transitioned from parenteral or inhaled prostacyclins: case series and treatment protocol

Oral treprostinil (TRE) is a prostacylin approved for the management of pulmonary arterial hypertension (PAH). Few data exist to guide the use of oral TRE as a replacement for parenteral or inhaled prostacyclins. Therefore, the purpose of this report was to describe our experience with oral TRE to transition patients from parenteral or inhaled TRE. We describe a case series of patients admitted for a 4-day hospital stay to transition from parenteral or inhaled TRE. Appropriate criteria for transition included stable patients with improved symptoms/functional capacity, patients who could not tolerate intravenous prostacyclin due to infection or subcutaneous prostacyclin due to pain, and patient preference for transition. The dosing protocol for transition is described. A total of 9 patients generally representative of a typical PAH demographic and background medical therapy were included. Patients were initiated at either 0.5 or 1 mg 3 times daily and discharged on a median dose of 8 mg 3 times daily. Our protocol resulted in 6 of 9 patients who successfully transitioned at a median follow-up of 47 weeks. Two patients had to return to their previous prostacyclin therapy based on the presence of clinical worsening and adverse events (n = 1) and adverse events alone (n = 1). Another patient discontinued therapy due to plans for hospice care. Oral TRE may serve an important role in prostacyclin transitions in carefully selected, stable patients who receive background oral therapy for PAH.

Sex and menopause differences in response to tadalafil: 6-minute walk distance and time to clinical worsening

Pulmonary arterial hypertension (PAH) is a female-predominant disease, but there are little data on treatment response by sex and menopausal status. In this retrospective analysis of the Pulmonary Arterial Hypertension and Response to Tadalafil (PHIRST) randomized clinical trial, we assessed treatment response between the sexes by examining change in 6-minute walk distance (6MWD) and time to clinical worsening (TCW). We examined the effect of menopausal status on the same treatment measures. 6MWD was recorded before and after 16 weeks of treatment with tadalafil or placebo in the PHIRST study cohort of 340 subjects (264 females, 76 males). A univariate analysis was used to assess the effect of sex on change in 6MWD and TCW. Multivariate linear regression and Cox proportional hazards models were built for 6MWD and TCW, respectively. Women were subdivided by age as a surrogate for menopausal status. The linear trend test and the log-rank test were performed on change in 6MWD and TCW by age. For tadalafil-treated patients, a significant difference in change in 6MWD by sex (mean: 48.6 m for males vs. 34.7 m for females; P = 0.01) was found, but it was not significant in multivariate analysis (P = 0.08). There was a trend toward a female age-dependent effect in change in 6MWD; the premenopausal group showed the greatest improvement. A significant sex- or age-dependent effect on TCW was not present. In conclusion, this retrospective analysis of the PHIRST trial suggests that men and premenopausal women may experience greater functional improvement when treated with tadalafil than older women, but there was no consistent sex or menopausal effect on TCW.

Pulmonary Hypertension in the Intensive Care Unit

Pulmonary hypertension occurs as the result of disease processes increasing pressure within the pulmonary circulation, eventually leading to right ventricular failure. Patients may become critically ill from complications of pulmonary hypertension and right ventricular failure or may develop pulmonary hypertension as the result of critical illness. Diagnostic testing should evaluate for common causes such as left heart failure, hypoxemic lung disease and pulmonary embolism. Relatively few patients with pulmonary hypertension encountered in clinical practice require specific pharmacologic treatment of pulmonary hypertension targeting the pulmonary vasculature. Management of right ventricular failure involves optimization of preload, maintenance of systemic blood pressure and augmentation of inotropy to restore systemic perfusion. Selected patients may require pharmacologic therapy to reduce right ventricular afterload by directly targeting the pulmonary vasculature, but only after excluding elevated left heart filling pressures and confirming increased pulmonary vascular resistance. Critically-ill patients with pulmonary hypertension remain at high risk of adverse outcomes, requiring a diligent and thoughtful approach to diagnosis and treatment.

[Treatment goals of pulmonary hypertension]

With significant therapeutic advances in the field of pulmonary arterial hypertension, the need to identify clinically relevant treatment goals that correlate with long-term outcome has emerged as 1 of the most critical tasks. Current goals include achieving modified New York Heart Association functional class I or II, 6-min walk distance >380 m, normalization of right ventricular size and function on echocardiograph, a decreasing or normalization of B-type natriuretic peptide (BNP), and hemodynamics with right atrial pressure <8 mm Hg and cardiac index >2.5 L/dk/m2. However, to more effectively prognosticate in the current era of complex treatments, it is becoming clear that the "bar" needs to be set higher, with more robust and clearer delineations aimed at parameters that correlate with long-term outcome; namely, exercise capacity and right heart function. Specifically, tests that accurately and noninvasively determine right ventricular function, such as cardiac magnetic resonance imaging and BNP/N-terminal pro-B-type natriuretic peptide, are emerging as promising indicators to serve as baseline predictors and treatment targets. Furthermore, studies focusing on outcomes have shown that no single test can reliably serve as a long-term prognostic marker and that composite treatment goals are more predictive of long-term outcome. It has been proposed that treatment goals be revised to include the following: modified New York Heart Association functional class I or II, 6-min walk distance 380 to 440 m, cardiopulmonary exercise test-measured peak oxygen consumption >15 ml/min/kg and ventilatory equivalent for carbon dioxide <45 l/min/l/min, BNP level toward "normal," echocardiograph and/or cardiac magnetic resonance imaging demonstrating normal/near-normal right ventricular size and function, and hemodynamics showing normalization of right ventricular function with right atrial pressure <8 mm Hg and cardiac index >2.5 to 3.0 l/min/m2. (J Am Coll Cardiol 2013;62:D73-81) ©2013 by the American College of Cardiology Foundation.

RV-pulmonary arterial coupling predicts outcome in patients referred for pulmonary hypertension

OBJECTIVE

Prognosis in pulmonary hypertension (PH) is largely determined by RV function. However, uncertainty remains about what metrics of RV function might be most clinically relevant. The purpose of this study was to assess the clinical relevance of metrics of RV functional adaptation to increased afterload.

METHODS

Patients referred for PH underwent right heart catheterisation and RV volumetric assessment within 48 h. A RV maximum pressure (Pmax) was calculated from the RV pressure curve. The adequacy of RV systolic functional adaptation to increased afterload was estimated either by a stroke volume (SV)/end-systolic volume (ESV) ratio, a Pmax/mean pulmonary artery pressure (mPAP) ratio, or by EF (RVEF). Diastolic function of the RV was estimated by a diastolic elastance coefficient β. Survival analysis was via Cox proportional HR, and Kaplan-Meier with the primary outcome of time to death or lung transplant.

RESULTS

Patients (n=50; age 58±13 yrs) covered a range of mPAP (13-79 mm Hg) with an average RVEF of 39±17% and ESV of 143±89 mL. Average estimates of the ratio of end-systolic ventricular to arterial elastance were 0.79±0.67 (SV/ESV) and 2.3±0.65 (Pmax/mPAP-1). Transplantation-free survival was predicted by right atrial pressure, mPAP, pulmonary vascular resistance, β, SV, ESV, SV/ESV and RVEF, but after controlling for right atrial pressure, mPAP, and SV, SV/ESV was the only independent predictor.

CONCLUSIONS

The adequacy of RV functional adaptation to afterload predicts survival in patients referred for PH. Whether this can simply be evaluated using RV volumetric imaging will require additional confirmation.

Role of baseline echocardiography in the preoperative management of liver transplant candidates

Liver transplantation (LT) has not traditionally been offered to patients with intracardiac shunts (ICSs) or pulmonary hypertension (PH). There is a paucity of data regarding cardiac structural characteristics in LT candidates. We examined echocardiographic characteristics and their role in managing LT candidates diagnosed with ICS and PH. We identified 502 consecutive patients (318 men, mean age 55 ± 11 years) who underwent LT and had preoperative echocardiogram. Demographics, cardiovascular risk factors, and echocardiographic variables were recorded and data were analyzed for end-stage liver disease diagnosis. ICSs were diagnosed with contrast echocardiography and PH was defined as estimated pulmonary artery systolic pressure >40 mm Hg. Primary end points included short-term (30-day) and long-term (mean 41-month) mortalities and the correlation between pre- and perioperative stroke. In our studied population >50% had >2 cardiovascular risk factors and with increasing frequency ICSs were diagnosed in 16%, PH in 25%, and intrapulmonary shunts in 41% of LT candidates. There was no correlation between short- and long-term mortality and ICS (p = 0.71 and 0.76, respectively) or PH (p = 0.79 and 0.71). Importantly, in those with ICS, no strokes occurred. In conclusion, structural differences exist between various end-stage liver disease diagnoses. ICSs diagnosed by echocardiography are not associated with an increased risk of perioperative stroke or increased mortality. A diagnosis of mild or moderate PH on baseline echocardiogram is not associated with worse outcomes and requires further assessment. Based on these findings, patients should not be excluded from consideration for LT based solely on the presence of an ICS or PH.

Overview of current therapeutic approaches for pulmonary hypertension

There have been tremendous strides in the management of pulmonary hypertension over the past 20 years with the introduction of targeted medical therapies and overall improvements in surgical treatment options and general supportive care. Furthermore, recent data shows that the survival of those with pulmonary arterial hypertension is improving. While there has been tremendous progress, much work remains to be done in improving the care of those with secondary forms of pulmonary hypertension, who constitute the majority of patients with this disorder, and in the optimal treatment approach in those with pulmonary arterial hypertension. This article will review general and targeted medical treatment, along with surgical interventions, of those with pulmonary hypertension.

Doppler-defined pulmonary hypertension in medical intensive care unit patients: Retrospective investigation of risk factors and impact on mortality

Pulmonary hypertension (PH) is poorly characterized in the critically ill. No prior studies describe the burden of or outcomes associated with PH in a general medical intensive care unit population. We hypothesize that PH is an important comorbidity prevalent in the modern medical intensive care unit. We undertook a preliminary investigation to define the consequences of Doppler-defined PH in the critically ill. A single-center retrospective case–control study of medical intensive care patients admitted over a 1-year period was conducted. Eligible patients had an echocardiogram within 4 days of admission. PH was defined to include both pulmonary arterial and venous hypertension and required a tricuspid regurgitant jet velocity ≥3 m/sec. Cases and controls were compared for comorbidities, illness severity, diagnoses, and mortality. Multivariable regression was performed to identify clinical features associated with PH and mortality. 299 (21% of admissions) patients had an eligible echocardiogram. Patients with PH (N=126) had a higher unadjusted mortality than did controls (N=173) (37% vs. 25%, P=0.04) and PH remained significantly associated with mortality after controlling for other clinical factors (HR=1.59, 95% CI=1.03–2.44, P=0.036). Low ejection fraction (OR=2.21, 95% CI=1.19–4.11, P=0.012) and pulmonary embolism (OR=4.28, 95% CI=1.59–11.5, P=0.004) were independently associated with PH. Doppler-defined PH is associated with mortality in the critically ill. Prospective studies are needed to define the prevalence of pulmonary venous hypertension versus pulmonary arterial hypertension, and the clinical consequences of each, in a general medical intensive care unit population.

The Nuts and Bolts of Interpreting Hemodynamics in Pulmonary Hypertension Associated With Diastolic Heart Failure

With the widespread application of transthoracic echocardiography as a screening tool for pulmonary hypertension (PH), we have come to appreciate the prevalence of PH associated with diastolic heart failure. Diastolic heart failure (DHF, sometimes called heart failure with preserved, or normal, left ventricular ejection fraction [HFpEF]) is quite common, and PH appears to be a fairly frequent component of DHF.1–3 The epidemiology of these conditions is described in the article by Dr Soto in this issue of Advances. There is a complex relationship between DHF and PH: the 2 may exist independent of each other or in combination; and when they exist in combination, the PH may be in proportion or out of proportion to the DHF. Cardiac catheterization is critical in differentiating among these patterns, and this distinction may lead to important modifications in treatment strategy. This requires, however, a full understanding of the proper performance and interpretation of cardiac catheterization, as well as the potential pitfalls that can limit the utility of the procedure. This article will discuss these aspects of cardiac catheterization as they pertain to patients with pulmonary arterial hypertension (PAH) and PH associated with DHF. A number of important aspects of cardiac catheterization are not covered here due to space limitations but can be obtained in a more detailed text.4

Identifying left ventricular dysfunction in pulmonary hypertension

The significance of left ventricular (LV) dysfunction in patients with pulmonary hypertension (PH) is unknown. Our purpose was to quantify LV function in PH patients by measuring LV myocardial performance index (MPI) and correlating it with invasively determined hemodynamic variables. The authors prospectively measured LV MPI via transthoracic echocardiography in 50 patients with PH (53+/-11 years; 35 women) who also underwent right heart catheterization within 1 day of echocardiography. For comparative purposes, LV MPI was also measured in 15 healthy volunteers who served as controls. LV MPI was significantly increased in the PH group compared with controls (0.62+/-0.27 vs 0.36+/-0.08; P<.001), indicating worse LV dysfunction despite that LV ejection fraction was not significantly different between the groups (58%+/-4% vs 60%+/-3%). LV MPI demonstrated significant correlations with invasively determined mean pulmonary artery pressure (r=.50; P<.001), pulmonary vascular resistance (r=.57; P<.001), and cardiac index (r=-.64; P<.001). By receiver operating characteristic analysis, LV MPI >0.75 predicted cardiac index <2 L/min/m(2) with 89% sensitivity and 78% specificity (area under the curve, 0.89). In a multivariate model, LV MPI was independently associated with cardiac index (P<.01). Patients with PH demonstrate abnormal LV function as quantified by elevated LV MPI, which correlates significantly with pulmonary vascular resistance and cardiac index.

Subcutaneous treprostinil in pulmonary arterial hypertension: Practical considerations

Treprostinil, which is available for subcutaneous (SC) and intravenous (IV) administration, has demonstrated efficacy in increasing exercise capacity, reducing signs and symptoms of pulmonary arterial hypertension (PAH), and improving cardiopulmonary hemodynamics in patients with PAH; however, the infusion site pain commonly experienced with SC treprostinil has limited its use. Prospective and observational clinical studies have shown that the dose of SC treprostinil can be escalated at a higher rate than described in early clinical trials to achieve symptom relief, in part because of favorable tolerability of treatment and the apparent dose independence of site pain. In addition, pain management protocols that include non-pharmacologic and pharmacologic (i.e., topical and systemic) approaches provide analgesic relief from infusion site pain. With experience, physicians and patients have recognized that some infusion sites are better than others, and the frequency of site rotation can be reduced to improve tolerability. Dosing to achieve rapid onset of efficacy and proactively managing infusion site pain enhance the likelihood for a patient with PAH to maintain and derive benefit from SC treprostinil therapy.

Phenotyping the right ventricle in patients with pulmonary hypertension

Right ventricular (RV) failure is associated with poor outcomes in pulmonary hypertension (PH). We sought to phenotype the RV in PH patients with compensated and decompensated RV function by quantifying regional and global RV structural and functional changes. Twenty-two patients (age 51 +/- 11, 14 females, mean pulmonary artery (PA) pressure range 13-79 mmHg) underwent right heart catheterization, echocardiography, and ECG-gated multislice computed tomography of the chest. Patients were divided into three groups: Normal, PH with hemodynamically compensated, and decompensated RV function (PH-C and PH-D, respectively). RV wall thickness (WT) was measured at end-diastole (ED) and end-systole (ES) in three regions: infundibulum, lateral free wall, and inferior free wall. Globally, RV volumes progressively increased from Normal to PH-C to PH-D and RV ejection fraction decreased. Regionally, WT increased and fractional wall thickening (FWT) decreased in a spatially heterogeneous manner. Infundibular wall stress was elevated and FWT was lower regardless of the status of global RV function. In PH, there are significant phenotypic abnormalities in the RV even in the absence of overt hemodynamic RV decompensation. Regional changes in RV structure and function may be early markers of patients at risk for developing RV failure.

Bosentan

IMPORTANCE TO THE FIELD

Pulmonary arterial hypertension (PAH) is a morbid condition with high mortality if left untreated. Bosentan is an effective treatment option for group 1 pulmonary arterial hypertension. Bosentan improves exercise tolerance and functional class and delays the time to clinical worsening in these patients. Investigation is ongoing to determine its efficacy in other groups of pulmonary hypertension.

AREAS COVERED IN THIS REVIEW

This review provides a background on endothelin activity in PAH, as a rationale for the use of bosentan in this disease. It also presents evidence from key clinical trials of bosentan and discusses future directions in the study of bosentan to help the clinician better understand the role of bosentan in PAH management.

WHAT THE READER WILL GAIN

i) An understanding of the rationale for using endothelin receptor antagonists in treating PAH; ii) an understanding of the clinical evidence to support bosentan for the treatment of PAH; and iii) an understanding of how to use bosentan optimally in the treatment of PAH.

TAKE HOME MESSAGE

Bosentan is an effective and safe treatment for patients with PAH. Patients with suspected PAH should be evaluated carefully as the use of bosentan in non-group 1 pulmonary hypertension is still being investigated. Patients on bosentan should be monitored with monthly liver transaminase testing. Coadministration with other drugs should be reviewed carefully as drug-drug interactions may be important.

Pulsatile left ventricular assist device support as a bridge to decision in patients with end-stage heart failure complicated by pulmonary hypertension

BACKGROUND

Severe pulmonary hypertension (PH) in heart failure (HF) is a risk factor for adverse outcomes after heart transplantation (HTx). Left ventricular assist devices (LVADs) improve pulmonary hemodynamics, but our understanding of the degree of improvement and the effect on outcomes is still evolving.

METHODS

We reviewed invasive pulmonary hemodynamics from 58 consecutive patients receiving LVAD support as a bridge to HTx from 1996 to 2003. The primary outcome was change in baseline transpulmonary gradient (TPG) during LVAD support and after HTx/recovery. The secondary outcome was post-HTx survival.

RESULTS

All patients (age, 49 +/- 14 years, 79% male, 40% ischemic) received a pulsatile LVAD (median support, 97 days; interquartile range [IQR], 31-222). Hemodynamic measurements were obtained at baseline (median, 1 day; IQR, 1-3), during early (median, 1 day; IQR, 0-4) and late (median, 75 days; IQR, 24-186) LVAD support, and after HTx/recovery (median, 28 days; IQR, 17-40). Improvement in TPG occurred throughout LVAD support and was sustained after HTx/recovery. Levels of TPG reductions in patients with a baseline TPG in the highest quartile (14.1-26.0 mm Hg) were 8.6 +/- 3.5 vs 6.5 +/- 3.1 mm Hg in the lowest quartile (2.0-7.7 mm Hg) during LVAD support (p = 0.102), with 90% vs 100% 30-day post-HTx survival (P = 0.113).

CONCLUSION

Pulmonary hemodynamics and post-HTx survival were similar after pulsatile LVAD support in patients with and without pre-implant PH. LVAD support may be a useful strategy to reverse PH in carefully selected patients, thus improving candidacy for HTx.

Tissue Doppler imaging of right ventricular decompensation in pulmonary hypertension

Right ventricular (RV) function is closely linked to outcomes in pulmonary hypertension (PH). The authors sought to evaluate RV myocardial strain in 3 groups of patients: normal, PH with compensated RV function (PH-C), and PH with decompensated RV function (PH-D). Fifty-six patients (aged 56+/-12 years; 40 women; mean pulmonary artery pressure [MPAP] range, 13-82 mm Hg) underwent right heart catheterization and 2-dimensional echocardiography with tissue Doppler imaging of the RV. Right atrial pressures were 6+/-3, 5+/-2, and 14+/-4 mm Hg; MPAP values were 19+/-3, 44+/-15, and 56+/-13 mm Hg; pulmonary vascular resistances were 1.4+/-0.4, 7.9+/-5.1, and 11.5+/-6.6 Wood units; and cardiac indices were 3.4+/-0.9, 2.8+/-0.8, and 2.2+/-0.7 L/min/m(2) (P<.05 for all for normal, PH-C, and PH-D patients), respectively. RV free wall strain decreased significantly among all 3 groups (-26%+/-6%, -19%+/-7%, and -14%+/-5%; P<.0001). RV free wall strain decreases in PH without hemodynamically decompensated RV function suggesting it may be a preceding step in the development of RV failure. This may be of particular use in following patients sequentially.

Effect of right ventricular versus biventricular pacing on electrical remodeling in the normal heart

BACKGROUND

Biventricular (BIV) pacing can improve cardiac function in heart failure by altering the mechanical and electric substrates. We investigated the effect of BIV versus right ventricular (RV) pacing on the normal heart.

METHODS AND RESULTS

Male New Zealand White rabbits (n=33) were divided into 3 groups: sham-operated (control), RV pacing, and BIV pacing groups. Four weeks after surgery, the native QT (P=0.004) interval was significantly shorter in the BIV group compared with the RV or sham-operated groups. Also, compared with rabbits in the RV group, rabbits in the BIV group had shorter RV effective refractory period at all cycle lengths and shorter LV paced QT interval during the drive train of stimuli and close to refractoriness (P<0.001 for all comparisons). Protein expression of the KVLQT1 was significantly increased in the BIV group compared with the RV and control groups, whereas protein expression of SCN5A and connexin43 was significantly decreased in the RV compared with the other study groups. Erg protein expression was significantly increased in both pacing groups compared with the controls.

CONCLUSIONS

In this rabbit model, we demonstrate a direct effect of BIV but not RV pacing on shortening the native QT interval as well as the paced QT interval during burst pacing and close to the ventricular effective refractory period. These findings underscore the fact that the effect of BIV pacing is partially mediated through direct electric remodeling and may have implications as to the effect of BIV pacing on arrhythmia incidence and burden.

Nitrite potently inhibits hypoxic and inflammatory pulmonary arterial hypertension and smooth muscle proliferation via xanthine oxidoreductase-dependent nitric oxide generation

BACKGROUND

Pulmonary arterial hypertension is a progressive proliferative vasculopathy of the small pulmonary arteries that is characterized by a primary failure of the endothelial nitric oxide and prostacyclin vasodilator pathways, coupled with dysregulated cellular proliferation. We have recently discovered that the endogenous anion salt nitrite is converted to nitric oxide in the setting of physiological and pathological hypoxia. Considering the fact that nitric oxide exhibits vasoprotective properties, we examined the effects of nitrite on experimental pulmonary arterial hypertension.

METHODS AND RESULTS

We exposed mice and rats with hypoxia or monocrotaline-induced pulmonary arterial hypertension to low doses of nebulized nitrite (1.5 mg/min) 1 or 3 times a week. This dose minimally increased plasma and lung nitrite levels yet completely prevented or reversed pulmonary arterial hypertension and pathological right ventricular hypertrophy and failure. In vitro and in vivo studies revealed that nitrite in the lung was metabolized directly to nitric oxide in a process significantly enhanced under hypoxia and found to be dependent on the enzymatic action of xanthine oxidoreductase. Additionally, physiological levels of nitrite inhibited hypoxia-induced proliferation of cultured pulmonary artery smooth muscle cells via the nitric oxide-dependent induction of the cyclin-dependent kinase inhibitor p21(Waf1/Cip1). The therapeutic effect of nitrite on hypoxia-induced pulmonary hypertension was significantly reduced in the p21-knockout mouse; however, nitrite still reduced pressures and right ventricular pathological remodeling, indicating the existence of p21-independent effects as well.

CONCLUSIONS

These studies reveal a potent effect of inhaled nitrite that limits pathological pulmonary arterial hypertrophy and cellular proliferation in the setting of experimental pulmonary arterial hypertension.

Chronic intermittent hypoxia increases left ventricular contractility in C57BL/6J mice

Intermittent hypoxia (IH) commonly occurs in patients with obstructive sleep apnea and can cause a wide range of pathology, including reduced left ventricular (LV) ejection fraction in rats as determined by echocardiography, in rodent models. We utilized echocardiography and pressure-volume (PV) loop analyses to determine whether LV contractility was decreased in inbred C57BL/6J mice exposed to IH and whether blockade of beta-adrenergic receptors modified the response to hypoxia. Adult male 9- to 10-wk-old mice were exposed to 4 wk of IH (nadir inspired O(2) 5-6% at 60 cycles/h for 12 h during the light period) or intermittent air (IA) as control. A second group of animals were exposed to the same regimen of IH or IA, but in the presence of nonspecific beta-blockade with propranolol. Cardiac function was assessed by echocardiography and PV loop analyses, and mRNA and protein expression in ventricular homogenates was determined. Contrary to our expectations, we found with PV loop analyses that LV ejection fraction (63.4 +/- 3.5 vs. 50.5 +/- 2.6%, P = 0.015) and other measures of LV contractility were increased in IH-exposed animals compared with IA controls. There were no changes in contractile proteins, atrial natriuretic peptide levels, LV posterior wall thickness, or heart weight with IH exposure. However, cAMP levels were elevated after IH, and propranolol administration attenuated the increase in LV contractility induced by IH exposure. We conclude that, contrary to our hypothesis, 4 wk of IH exposure in C57BL/6J mice causes an increase in LV contractility that occurs independent of ventricular hypertrophy and is, in part, mediated by activation of cardiac beta-adrenergic pathways.