Variation in risk-adjusted cardiac intensive care unit (CICU) length of stay and the association with in-hospital mortality: An analysis from the Critical Care Cardiology Trials Network (CCCTN) registry

BACKGROUND

Previous studies have suggested that there is wide variability in cardiac intensive care unit (CICU) length of stay (LOS); however, these studies are limited by the absence of detailed risk assessment at the time of admission. Thus, we evaluated inter-hospital differences in CICU LOS, and the association between LOS and in-hospital mortality.

METHODS

Using data from the Critical Care Cardiology Trials Network (CCCTN) registry, we included 22,862 admissions between 2017 and 2022 from 35 primarily tertiary and quaternary CICUs that captured consecutive admissions in annual 2-month snapshots. The primary analysis compared inter-hospital differences in CICU LOS, as well as the association between CICU LOS and all-cause in-hospital mortality using a Fine and Gray competing risk model.

RESULTS

The overall median CICU LOS was 2.2 (1.1-4.8) days, and the median hospital LOS was 5.9 (2.8-12.3) days. Admissions in the longest tertile of LOS tended to be younger with higher rates of pre-existing comorbidities, and had higher Sequential Organ Failure Assessment (SOFA) scores, as well as higher rates of mechanical ventilation, intravenous vasopressor use, mechanical circulatory support, and renal replacement therapy. Unadjusted all-cause in-hospital mortality was 9.3%, 6.7%, and 13.4% in the lowest, intermediate, and highest CICU LOS tertiles. In a competing risk analysis, individual patient CICU LOS was correlated (r2 = 0.31) with a higher risk of 30-day in-hospital mortality. The relationship remained significant in admissions with heart failure, ST-elevation myocardial infarction and non-ST segment elevation myocardial infarction.

CONCLUSIONS

In a large registry of academic CICUs, we observed significant variation in CICU LOS and report that LOS is independently associated with all-cause in-hospital mortality. These findings could potentially be used to improve CICU resource utilization planning and refine risk prognostication in critically ill cardiovascular patients.

Modes of Death in Patients with Cardiogenic Shock in the Cardiac Intensive Care Unit: A Report from the Critical Care Cardiology Trials Network

BACKGROUND

There are limited data on how patients with cardiogenic shock (CS) die.

METHODS

The Critical Care Cardiology Trials Network is a research network of cardiac intensive care units coordinated by the Thrombolysis In Myocardial Infarction (TIMI) Study Group (Boston, MA). Using standardized definitions, site investigators classified direct modes of in-hospital death for CS admissions (October 2021 to September 2022). Mutually exclusive categories included 4 modes of cardiovascular death and 4 modes of noncardiovascular death. Subgroups defined by CS type, preceding cardiac arrest (CA), use of temporary mechanical circulatory support (tMCS), and transition to comfort measures were evaluated.

RESULTS

Among 1068 CS cases, 337 (31.6%) died during the index hospitalization. Overall, the mode of death was cardiovascular in 82.2%. Persistent CS was the dominant specific mode of death (66.5%), followed by arrhythmia (12.8%), anoxic brain injury (6.2%), and respiratory failure (4.5%). Patients with preceding CA were more likely to die from anoxic brain injury (17.1% vs 0.9%; P < .001) or arrhythmia (21.6% vs 8.4%; P < .001). Patients managed with tMCS were more likely to die from persistent shock (P < .01), both cardiogenic (73.5% vs 62.0%) and noncardiogenic (6.1% vs 2.9%).

CONCLUSIONS

Most deaths in CS are related to direct cardiovascular causes, particularly persistent CS. However, there is important heterogeneity across subgroups defined by preceding CA and the use of tMCS.

Interhospital Variation in Admissions Managed With Critical Care Therapies or Invasive Hemodynamic Monitoring in Tertiary Cardiac Intensive Care Units: An Analysis From the Critical Care Cardiology Trials Network Registry

BACKGROUND

Wide interhospital variations exist in cardiovascular intensive care unit (CICU) admission practices and the use of critical care restricted therapies (CCRx), but little is known about the differences in patient acuity, CCRx utilization, and the associated outcomes within tertiary centers.

METHODS

The Critical Care Cardiology Trials Network is a multicenter registry of tertiary and academic CICUs in the United States and Canada that captured consecutive admissions in 2-month periods between 2017 and 2022. This analysis included 17 843 admissions across 34 sites and compared interhospital tertiles of CCRx (eg, mechanical ventilation, mechanical circulatory support, continuous renal replacement therapy) utilization and its adjusted association with in-hospital survival using logistic regression. The Pratt index was used to quantify patient-related and institutional factors associated with CCRx variability.

RESULTS

The median age of the study population was 66 (56-77) years and 37% were female. CCRx was provided to 62.2% (interhospital range of 21.3%-87.1%) of CICU patients. Admissions to CICUs with the highest tertile of CCRx utilization had a greater burden of comorbidities, had more diagnoses of ST-elevation myocardial infarction, cardiac arrest, or cardiogenic shock, and had higher Sequential Organ Failure Assessment scores. The unadjusted in-hospital mortality (median, 12.7%) was 9.6%, 11.1%, and 18.7% in low, intermediate, and high CCRx tertiles, respectively. No clinically meaningful differences in adjusted mortality were observed across tertiles when admissions were stratified by the provision of CCRx. Baseline patient-level variables and institutional differences accounted for 80% and 5.3% of the observed CCRx variability, respectively.

CONCLUSIONS

In a large registry of tertiary and academic CICUs, there was a >4-fold interhospital variation in the provision of CCRx that was primarily driven by differences in patient acuity compared with institutional differences. No differences were observed in adjusted mortality between low, intermediate, and high CCRx utilization sites.

Prognostic significance of haemodynamic parameters in patients with cardiogenic shock

AIMS

Invasive haemodynamic assessment with a pulmonary artery catheter is often used to guide the management of patients with cardiogenic shock (CS) and may provide important prognostic information. We aimed to assess prognostic associations and relationships to end-organ dysfunction of presenting haemodynamic parameters in CS.

METHODS AND RESULTS

The Critical Care Cardiology Trials Network is an investigator-initiated multicenter registry of cardiac intensive care units (CICUs) in North America coordinated by the TIMI Study Group. Patients with CS (2018-2022) who underwent invasive haemodynamic assessment within 24 h of CICU admission were included. Associations of haemodynamic parameters with in-hospital mortality were assessed using logistic regression, and associations with presenting serum lactate were assessed using least squares means regression. Sensitivity analyses were performed excluding patients on temporary mechanical circulatory support and adjusted for vasoactive-inotropic score. Among the 3603 admissions with CS, 1473 had haemodynamic data collected within 24 h of CICU admission. The median cardiac index was 1.9 (25th-75th percentile, 1.6-2.4) L/min/m2 and mean arterial pressure (MAP) was 74 (66-86) mmHg. Parameters associated with mortality included low MAP, low systolic blood pressure, low systemic vascular resistance, elevated right atrial pressure (RAP), elevated RAP/pulmonary capillary wedge pressure ratio, and low pulmonary artery pulsatility index. These associations were generally consistent when controlling for the intensity of background pharmacologic and mechanical haemodynamic support. These parameters were also associated with higher presenting serum lactate.

CONCLUSION

In a contemporary CS population, presenting haemodynamic parameters reflecting decreased systemic arterial tone and right ventricular dysfunction are associated with adverse outcomes and systemic hypoperfusion.

The association between pulmonary artery enlargement and mortality in an Emergency Department population undergoing computed tomography pulmonary angiography

Findings of an enlarged pulmonary artery diameter (PAd) and increased pulmonary artery to ascending aorta ratio (PA:AA) on contrast-enhanced computed tomography pulmonary angiography (CTPA) are associated with increased mortality in particular groups of patients with cardiopulmonary disease. However, the frequency and prognostic significance of these incidental findings has not been studied in unselected patients evaluated in the Emergency Department (ED). This study aims to determine the prevalence and associated prognosis of enlarged pulmonary artery measurements in an ED cohort. We measured PA and AA diameters on 990 CTPA studies performed in the ED. An enlarged PA diameter was defined as >27 mm in females and >29 mm in males, while an increased PA:AA was defined as >0.9. Poisson regression was performed to calculate prevalence ratios for relevant comorbidities, and multivariable Cox regression was performed to calculate hazard ratios (HR) for mortality of patients with enlarged pulmonary artery measurements. An enlarged PAd was observed in 27.9% of 990 patients and was more commonly observed in older patients and in patients with obesity or heart failure. Conversely, PA:AA was increased in 34.2% of subjects, and was more common in younger patients and those with peripheral vascular disease or obesity. After controlling for age, sex, and comorbidities, both enlarged PAd (HR 1.29, 95% CI 1.00-1.68, p = 0.05) and PA:AA (HR 1.70, 95% CI 1.31-2.22 p < 0.01) were independently associated with mortality. In sum, enlarged PAd and increased PA:AA are common in patients undergoing CTPAs in the ED setting and both are independently associated with mortality.

Frequency of Thrombotic Risk Factors in Patients with Chronic Thromboembolic Pulmonary Hypertension and Acute Pulmonary Embolism: A Case-Control Study

Chronic thromboembolic pulmonary hypertension (CTEPH) is a serious complication of acute pulmonary embolism (PE) which remains underdiagnosed. A better understanding of risk factors for CTEPH would improve our ability to predict which PE survivors are at risk. Several medical conditions-including malignancy, splenectomy, thyroid hormone supplementation, the presence of an intravascular device, inflammatory bowel disease, osteomyelitis, and non-O blood group-have been associated with increased risk of CTEPH, primarily in studies comparing patients with CTEPH to individuals with non-thrombotic conditions. Because many of these conditions increase thrombosis risk, it remains unclear whether their association with CTEPH reflects a general effect on thrombosis risk, or a specific effect on the risk of developing CTEPH as an outcome of thrombosis. We performed a case-control study comparing the frequencies of these conditions in patients with CTEPH versus patients with acute PE who did not develop CTEPH. The conditions studied were equally frequent in the CTEPH and PE cohorts, although there was a trend towards an increased frequency of splenectomy and non-O blood group among the CTEPH cohort. Thus, other than the possible exceptions of splenectomy and non-O blood group, the investigated medical conditions do not appear likely to increase the risk of CTEPH as an outcome of acute PE, and thus are unlikely to be useful in predicting CTEPH risk among PE survivors.

Implementation of 11 system-wide, disease-specific, multidisciplinary tumor boards connecting 24 hospitals in an integrated health care system

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Background: Cancer treatment is becoming more complex, necessitating subspecialty expertise and multidisciplinary approaches to treatment planning. Simultaneously, there is increasing demand to provide care as close to home as possible. While tumor boards have long been an institutional backbone to providing high-quality multidisciplinary care in tertiary facilities, connecting several hospitals and dozens of cancer specialists in a large integrated healthcare system is unique and potentially transformational for smaller facilities and communities. Methods: Using highly-secure, network firewall-protected Cisco Telepresence and WebEx capabilities, 11 disease specific tumor boards (Breast, GI, Sarcoma, GU, Thoracic, Head/Neck, Melanoma, Neuro, Heme, Hepatobiliary, Gyn) were organized across Intermountain Healthcare’s 24 geographically and medically diverse hospitals spanning over 500 miles. Meetings for each of these disease-specific tumor boards have been held at least every 1-2 weeks, at set times and days since July 2019. Cases are submitted to the appropriate tumor board by individual providers from anywhere in the system. Submitted cases are reviewed by a designated subspeciality leader. Cases are either added to the system-wide agenda, or at times, the clinical decision can be resolved immediately. Included cases’ records including pathology, radiology and pertinent medical history are obtained for display and discussion. After each tumor board, recommendations and conclusions are recorded by nurse navigators for future review and consultation. Results: From July 2019 to February 2020, 1,598 patient cases were discussed. Just as relevant, 293 unique oncology providers (surgeons, medical oncologists, radiation oncologists, genetic counselors, nurse navigators, and therapists) participated in tumor board discussions. These deliberations provided insight, experience and recommendations directly related to patient care. Conclusions: Our system-wide, disease-specific, multi-disciplinary tumor boards are useful in connecting oncology providers and subspecialists. This effort has led to better collaboration, coordination and delivery of high-quality cancer care to patients throughout a large healthcare system that includes thousands of patients and dozens of cancer providers in smaller/rural communities. In addition, provider engagement has improved. Work is ongoing to prospectively evaluate the effects on treatment decisions and clinical outcomes.

Capillary Proliferation in Systemic-Sclerosis-Related Pulmonary Fibrosis: Association with Pulmonary Hypertension

Objective

We sought to determine if any histopathologic component of the pulmonary microcirculation can distinguish systemic sclerosis (SSc)‐related pulmonary fibrosis (PF) with and without pulmonary hypertension (PH).

Methods

Two pulmonary pathologists blindly evaluated 360 histologic slides from lungs of 31 SSc‐PF explants or autopsies with (n = 22) and without (n = 9) PH. The presence of abnormal small arteries, veins, and capillaries (pulmonary microcirculation) was semiquantitatively assessed in areas of preserved lung architecture. Capillary proliferation (CP) within the alveolar walls was measured by its distribution, extent (CP % involvement), and maximum number of layers (maximum CP). These measures were then evaluated to determine the strength of their association with right heart catheterization–proven PH.

Results

Using consensus measures, all measures of CP were significantly associated with PH. Maximum CP had the strongest association with PH (P = 0.013; C statistic 0.869). Maximum CP 2 or more layers and CP % involvement 10% or greater were the optimal thresholds that predicted PH, both with a sensitivity of 56% and specificity of 91%. The CP was typically multifocal rather than focal or diffuse and was associated with a background pattern of usual interstitial pneumonia. There was a significant but weaker relationship between the presence of abnormal small arteries and veins and PH.

Conclusion

In the setting of advanced SSc‐PF, the histopathologic feature of the pulmonary microcirculation best associated with PH was capillary proliferation in architecturally preserved lung areas.

Pulmonary Arterial Hypertension

This article provides an overview of pulmonary arterial hypertension (PAH), beginning with the initial pathologic recognition of pulmonary hypertension more than 100 years ago and progressing to the current diagnostic categorization of PAH. It reviews the epidemiology, pathophysiology, genetics, and modern treatment of PAH. The article discusses several important recent studies that have highlighted the importance of new management strategies, including serial risk assessment and combination pharmacotherapy.

EIF2AK4 Mutations in Patients Diagnosed With Pulmonary Arterial Hypertension

BACKGROUND

Differentiating pulmonary venoocclusive disease (PVOD) and pulmonary capillary hemangiomatosis (PCH) from idiopathic pulmonary arterial hypertension (IPAH) or heritable pulmonary arterial hypertension (HPAH) is important clinically. Mutations in eukaryotic translation initiation factor 2 alpha kinase 4 (EIF2AK4) cause heritable PVOD and PCH, whereas mutations in other genes cause HPAH. The aim of this study was to describe the frequency of pathogenic EIF2AK4 mutations in patients diagnosed clinically with IPAH or HPAH.

METHODS

Sanger sequencing and deletion/duplication analysis were performed to detect mutations in the bone morphogenetic protein receptor type II (BMPR2) gene in 81 patients diagnosed at 30 North American medical centers with IPAH (n = 72) or HPAH (n = 9). BMPR2 mutation-negative patients (n = 67) were sequenced for mutations in four other genes (ACVRL1, ENG, CAV1, and KCNK3) known to cause HPAH. Patients negative for mutations in all known PAH genes (n = 66) were then sequenced for mutations in EIF2AK4. We assessed the pathogenicity of EIF2AK4 mutations and reviewed clinical characteristics of patients with pathogenic EIF2AK4 mutations.

RESULTS

Pathogenic BMPR2 mutations were identified in 8 of 72 (11.1%) patients with IPAH and 6 of 9 (66.7%) patients with HPAH. A novel homozygous EIF2AK4 mutation (c.257+4A>C) was identified in 1 of 9 (11.1%) patients diagnosed with HPAH. The novel EIF2AK4 mutation (c.257+4A>C) was homozygous in two sisters with severe pulmonary hypertension. None of the 72 patients with IPAH had biallelic EIF2AK4 mutations.

CONCLUSIONS

Pathogenic biallelic EIF2AK4 mutations are rarely identified in patients diagnosed with HPAH. Identification of pathogenic biallelic EIF2AK4 mutations can aid clinicians in differentiating HPAH from heritable PVOD or PCH.

Novel ethyl methanesulfonate (EMS)-induced null alleles of the Drosophila homolog of LRRK2 reveal a crucial role in endolysosomal functions and autophagy in vivo

Mutations in LRRK2 cause a dominantly inherited form of Parkinson’s disease (PD) and are the most common known genetic determinant of PD. Inhibitor-based therapies targeting LRRK2 have emerged as a key therapeutic strategy in PD; thus, understanding the consequences of inhibiting the normal cellular functions of this protein is vital. Despite much interest, the physiological functions of LRRK2 remain unclear. Several recent studies have linked the toxicity caused by overexpression of pathogenic mutant forms of LRRK2 to defects in the endolysosomal and autophagy pathways, raising the question of whether endogenous LRRK2 might play a role in these processes. Here, we report the characterization of multiple novel ethyl methanesulfonate (EMS)-induced nonsense alleles in the Drosophila LRRK2 homolog, lrrk. Using these alleles, we show that lrrk loss-of-function causes striking defects in the endolysosomal and autophagy pathways, including the accumulation of markedly enlarged lysosomes that are laden with undigested contents, consistent with a defect in lysosomal degradation. lrrk loss-of-function also results in the accumulation of autophagosomes, as well as the presence of enlarged early endosomes laden with mono-ubiquitylated cargo proteins, suggesting an additional defect in lysosomal substrate delivery. Interestingly, the lysosomal abnormalities in these lrrk mutants can be suppressed by a constitutively active form of the small GTPase rab9, which promotes retromer-dependent recycling from late endosomes to the Golgi. Collectively, our data provides compelling evidence of a vital role for lrrk in lysosomal function and endolysosomal membrane transport in vivo, and suggests a link between lrrk and retromer-mediated endosomal recycling.

Roles of the Drosophila LRRK2 homolog in Rab7-dependent lysosomal positioning

LRRK2 (PARK8) is the most common genetic determinant of Parkinson's disease (PD), with dominant mutations in LRRK2 causing inherited PD and sequence variation at the LRRK2 locus associated with increased risk for sporadic PD. Although LRRK2 has been implicated in diverse cellular processes encompassing almost all cellular compartments, the precise functions of LRRK2 remain unclear. Here, we show that the Drosophila homolog of LRRK2 (Lrrk) localizes to the membranes of late endosomes and lysosomes, physically interacts with the crucial mediator of late endosomal transport Rab7 and negatively regulates rab7-dependent perinuclear localization of lysosomes. We also show that a mutant form of lrrk analogous to the pathogenic LRRK2(G2019S) allele behaves oppositely to wild-type lrrk in that it promotes rather than inhibits rab7-dependent perinuclear lysosome clustering, with these effects of mutant lrrk on lysosome position requiring both microtubules and dynein. These data suggest that LRRK2 normally functions in Rab7-dependent lysosomal positioning, and that this function is disrupted by the most common PD-causing LRRK2 mutation, linking endolysosomal dysfunction to the pathogenesis of LRRK2-mediated PD.

Pink1, Parkin, DJ-1 and mitochondrial dysfunction in Parkinson's disease

Mutations in PARKIN, PTEN-induced kinase 1 (PINK1) and DJ-1 are found in autosomal recessive forms and some sporadic cases of Parkinson's disease. Recent work on these genes underscores the central importance of mitochondrial dysfunction and oxidative stress in Parkinson's disease. In particular, pink1 and parkin loss-of-function mutants in Drosophila show similar phenotypes, and pink1 acts upstream of parkin in a common genetic pathway to regulate mitochondrial function. DJ-1 has a role in oxidative stress protection, but a direct role of DJ-1 in mitochondrial function has not been fully established. Importantly, defects in mitochondrial function have also been identified in patients who carry both PINK1 and PARKIN mutations, and in those who have sporadic Parkinson's disease. Future studies of the biochemical interactions between Pink1 and Parkin, and identification of other components in this pathway, are likely to provide insight into Parkinson's disease pathogenesis, and might identify new therapeutic targets.

Drosophila pink1 is required for mitochondrial function and interacts genetically with parkin

Parkinson's disease is the second most common neurodegenerative disorder and is characterized by the degeneration of dopaminergic neurons in the substantia nigra. Mitochondrial dysfunction has been implicated as an important trigger for Parkinson's disease-like pathogenesis because exposure to environmental mitochondrial toxins leads to Parkinson's disease-like pathology. Recently, multiple genes mediating familial forms of Parkinson's disease have been identified, including PTEN-induced kinase 1 (PINK1; PARK6) and parkin (PARK2), which are also associated with sporadic forms of Parkinson's disease. PINK1 encodes a putative serine/threonine kinase with a mitochondrial targeting sequence. So far, no in vivo studies have been reported for pink1 in any model system. Here we show that removal of Drosophila PINK1 homologue (CG4523; hereafter called pink1) function results in male sterility, apoptotic muscle degeneration, defects in mitochondrial morphology and increased sensitivity to multiple stresses including oxidative stress. Pink1 localizes to mitochondria, and mitochondrial cristae are fragmented in pink1 mutants. Expression of human PINK1 in the Drosophila testes restores male fertility and normal mitochondrial morphology in a portion of pink1 mutants, demonstrating functional conservation between human and Drosophila Pink1. Loss of Drosophila parkin shows phenotypes similar to loss of pink1 function. Notably, overexpression of parkin rescues the male sterility and mitochondrial morphology defects of pink1 mutants, whereas double mutants removing both pink1 and parkin function show muscle phenotypes identical to those observed in either mutant alone. These observations suggest that pink1 and parkin function, at least in part, in the same pathway, with pink1 functioning upstream of parkin. The role of the pink1-parkin pathway in regulating mitochondrial function underscores the importance of mitochondrial dysfunction as a central mechanism of Parkinson's disease pathogenesis.

Overexpression of nicastrin increases Abeta production

Gamma-secretase cleavage is the final proteolytic step that releases the amyloid beta-peptide (Abeta) from the amyloid beta-protein precursor (APP). Significant evidence indicates that the presenilins (PS) are catalytic components of a high molecular weight gamma-secretase complex. The glycoprotein nicastrin was recently identified as a functional unit of this complex based on 1) binding to PS and 2) the ability to modulate Abeta production following mutation of a conserved DYIGS region. In contrast to the initial report, we find that overexpression of wild-type (WT) nicastrin increases Abeta production, whereas DYIGS mutations (MT) have little or no effect. The increase in Abeta production is associated with an increase in gamma-secretase activity but not with a detectable increase in PS1 levels. Subcellular fractionation studies show that WT but not MT nicastrin matures into buoyant membrane fractions enriched in gamma-secretase activity. These data support the hypothesis that nicastrin is an essential component of the gamma-secretase complex. The finding that WT nicastrin overexpression can increase gamma-secretase activity without altering levels of the presumed catalytic component (PS) of the enzyme may point to a role for nicastrin in facilitating cleavage by regulating substrate interactions with the gamma-secretase complex.