Cardiac rehabilitation for heart failure: progress and gaps in evidence and policy

PURPOSE OF REVIEW

This review synthesizes recent research on the efficacy, optimal design, and delivery methods of cardiac rehabilitation tailored to heart failure patients. Despite established benefits, cardiac rehabilitation referral and access disparities persist, necessitating elucidation of limitations and solutions.

RECENT FINDINGS

Exercise-based cardiac rehabilitation improves long-term mortality and hospitalization rates but not short-term mortality. cardiac rehabilitation further enhances quality of life and medical therapy adherence. However, cardiac rehabilitation relies on in-person delivery, presenting access barriers exacerbated during COVID-19. Significant geographic disparities exist, with analyses indicating current capacity only serves 45% of eligible US adults even if fully utilized. Referral rates also lag, disproportionately affecting women and minority groups. Research increasingly focuses on home-based and digital therapeutics modalities to expand reach, with evidence demonstrating comparable improvements across settings. Protocols and research center on heart failure with reduced ejection fraction (HFrEF), despite growing heart failure with preserved ejection fraction (HFpEF) prevalence.

SUMMARY

Increasing referrals through standardized procedures and addressing multifactorial geographic, economic, and capacity limitations are imperative to ensure equitable cardiac rehabilitation access. Broadening HFpEF rehabilitation research and care standards also constitutes a critical practice gap requiring alignment with projected epidemiologic shifts. Advancing patient-centered, evidence-based solutions can promote rehabilitation as essential secondary prevention for wider cardiac populations.

VIDEO ABSTRACT

http://links.lww.com/HCO/A97.

Purulent pericarditis caused by methicillin-sensitive Staphylococcus aureus bacteriuria

BACKGROUND

Purulent pericarditis (PP)- a purulent infection involving the pericardial space-requires a high index of suspicion for diagnosis as it often lacks characteristic signs of pericarditis and carries a mortality rate as high as 40% even with treatment. Common risk factors include immunosuppression, diabetes mellitus, thoracic surgery, malignancy, and uremia. Most reported cases of PP occur in individuals with predisposing risk factors, such as immunosuppression, and result from more commonly observed preceding infections, such as pneumonia, osteomyelitis, and meningitis. We report a case of PP due to asymptomatic bacteriuria in a previously immunocompetent individual on a short course of high-dose steroids.

CASE PRESENTATION

An 81-year-old male presented for severe epigastric pain that worsened with inspiration. He had been on high-dose prednisone for presumed inflammatory hip pain. History was notable for urinary retention requiring intermittent self-catheterization and asymptomatic bacteriuria and urinary tract infections due to methicillin-sensitive Staphylococcus aureus (MSSA). During the index admission he was found to have a moderate pericardial effusion. Pericardial fluid cultures grew MSSA that had an identical antibiogram to that of the urine cultures. A diagnosis of purulent pericarditis was made.

CONCLUSION

PP requires a high index of suspicion, especially in hosts with atypical risk factors. This is the second case of PP occurring as a result of asymptomatic MSSA bacteriuria. Through reporting this case we hope to highlight the importance of early recognition of PP and the clinical implications of asymptomatic MSSA bacteriuria in the setting of urinary instrumentation and steroid use.

Performance of Computed Tomographic Angiography-Based Aortic Valve Area for Assessment of Aortic Stenosis

Background A total of 40% of patients with severe aortic stenosis (AS) have low-gradient AS, raising uncertainty about AS severity. Aortic valve calcification, measured by computed tomography (CT), is guideline-endorsed to aid in such cases. The performance of different CT-derived aortic valve areas (AVAs) is less well studied. Methods and Results Consecutive adult patients with presumed moderate and severe AS based on echocardiography (AVA measured by continuity equation on echocardiography <1.5 cm2) who underwent cardiac CT were identified retrospectively. AVAs, measured by direct planimetry on CT (AVACT) and by a hybrid approach (AVA measured in a hybrid manner with echocardiography and CT [AVAHybrid]), were measured. Sex-specific aortic valve calcification thresholds (≥1200 Agatston units in women and ≥2000 Agatston units in men) were applied to adjudicate severe or nonsevere AS. A total of 215 patients (38.0% women; mean±SD age, 78±8 years) were included: normal flow, 59.5%; and low flow, 40.5%. Among the different thresholds for AVACT and AVAHybrid, diagnostic performance was the best for AVACT <1.2 cm2 (sensitivity, 85%; specificity, 26%; and accuracy, 72%), with no significant difference by flow status. The percentage of patients with correctly classified AS severity (correctly classified severe AS+correctly classified moderate AS) was as follows; AVA measured by continuity equation on echocardiography <1.0 cm2, 77%; AVACT <1.2 cm2, 73%; AVACT <1.0 cm2, 58%; AVAHybrid <1.2 cm2, 59%; and AVAHybrid <1.0 cm2, 45%. AVACT cut points of 1.52 cm2 for normal flow and 1.56 cm2 for low flow, provided 95% specificity for excluding severe AS. Conclusions CT-derived AVAs have poor discrimination for AS severity. Using an AVACT <1.2-cm2 threshold to define severe AS can produce significant error. Larger AVACT thresholds improve specificity.

Single-cell transcriptome analysis of xenotransplanted human retinal organoids defines two migratory cell populations of nonretinal origin

Human retinal organoid transplantation could potentially be a treatment for degenerative retinal diseases. How the recipient retina regulates the survival, maturation, and proliferation of transplanted organoid cells is unknown. We transplanted human retinal organoid-derived cells into photoreceptor-deficient mice and conducted histology and single-cell RNA sequencing alongside time-matched cultured retinal organoids. Unexpectedly, we observed human cells that migrated into all recipient retinal layers and traveled long distances. Using an unbiased approach, we identified these cells as astrocytes and brain/spinal cord-like neural precursors that were absent or rare in stage-matched cultured organoids. In contrast, retinal progenitor-derived rods and cones remained in the subretinal space, maturing more rapidly than those in the cultured controls. These data suggest that recipient microenvironment promotes the maturation of transplanted photoreceptors while inducing or facilitating the survival of migratory cell populations that are not normally derived from retinal progenitors. These findings have important implications for potential cell-based treatments of retinal diseases.

Characterization and allogeneic transplantation of a novel transgenic cone-rich donor mouse line

OBJECTIVES

Cone photoreceptor transplantation is a potential treatment for macular diseases. The optimal conditions for cone transplantation are poorly understood, partly because of the scarcity of cones in donor mice. To facilitate allogeneic cone photoreceptor transplantation studies in mice, we aimed to create and characterize a donor mouse model containing a cone-rich retina with a cone-specific enhanced green fluorescent protein (EGFP) reporter.

METHODS

We generated OPN1LW-EGFP/NRL^-/- mice by crossing NRL^-/- and OPN1LW-EGFP mice. We characterized the anatomical phenotype of OPN1LW-EGFP/NRL^-/- mice using multimodal confocal scanning laser ophthalmoscopy (cSLO) imaging, immunohistology, and transmission electron microscopy. We evaluated retinal function using electroretinography (ERG), including 465 and 525 nm chromatic stimuli. Retinal sheets and cell suspensions from OPN1LW-EGFP/NRL^-/- mice were transplanted subretinally into immunodeficient Rd1 mice.

RESULTS

OPN1LW-EGFP/NRL^-/- retinas were enriched with OPN1LW-EGFP⁺ and S-opsin⁺ cone photoreceptors in a dorsal-ventral distribution gradient. Cone photoreceptors co-expressing OPNL1W-EGFP and S-opsin significantly increased in OPN1LW-EGFP/NRL^-/- compared to OPN1LW-EGFP mice. Temporal dynamics of rosette formation in the OPN1LW-EGFP/NRL^-/- were similar as the NRL^-/- with peak formation at P15. Rosettes formed preferentially in the ventral retina. The outer retina in P35 OPN1LW-EGFP/NRL^-/- was thinner than NRL^-/- controls. The OPN1LW-EGFP/NRL^-/- ERG response amplitudes to 465 nm stimulation were similar to, but to 535 nm stimulation were lower than, NRL^-/- controls. Three months after transplantation, the suspension grafts showed greater macroscopic degradation than sheet grafts. Retinal sheet grafts from OPN1LW-EGFP/NRL^-/- mice showed greater S-opsin ⁺ cone survival than suspension grafts from the same strain.

CONCLUSIONS

OPN1LW-EGFP/NRL^-/- retinae were enriched with S-opsin⁺ photoreceptors. Sustained expression of EGFP facilitated the longitudinal tracking of transplanted donor cells. Transplantation of cone-rich retinal grafts harvested prior to peak rosette formation survived and differentiated into cone photoreceptor subtypes. Photoreceptor sheet transplantation may promote greater macroscopic graft integrity and S-opsin⁺ cone survival than cell suspension transplantation, although the mechanism underlying this observation is unclear at present. This novel cone-rich reporter mouse strain may be useful to study the influence of graft structure on cone survival.

Quantifiable In Vivo Imaging Biomarkers of Retinal Regeneration by Photoreceptor Cell Transplantation

Purpose

Short-term improvements in retinal anatomy are known to occur in preclinical models of photoreceptor transplantation. However, correlative changes over the long term are poorly understood. We aimed to develop a quantifiable imaging biomarker grading scheme, using noninvasive multimodal confocal scanning laser ophthalmoscopy (cSLO) imaging, to enable serial evaluation of photoreceptor transplantation over the long term.

Methods

Photoreceptor cell suspensions or sheets from rhodopsin-green fluorescent protein mice were transplanted subretinally, into either NOD.CB17-Prkdc^scid/J or C3H/HeJ-Pde6b^rd1 mice. Multimodal cSLO imaging was performed serially for up to three months after transplantation. Imaging biomarkers were scored, and a grade was defined for each eye by integrating the scores. Image grades were correlated with immunohistochemistry (IHC) data.

Results

Multimodal imaging enabled the extraction of quantitative imaging biomarkers including graft size, GFP intensity, graft length, on-target graft placement, intra-graft lamination, hemorrhage, retinal atrophy, and periretinal proliferation. Migration of transplanted material was observed. Changes in biomarker scores and grades were detected in 14/16 and 7/16 eyes, respectively. A high correlation was found between image grades and IHC parameters.

Conclusions

Serial evaluation of multiple imaging biomarkers, when integrated into a per-eye grading scheme, enabled comprehensive tracking of longitudinal changes in photoreceptor cell grafts over time. The application of systematic multimodal in vivo imaging could be useful in increasing the efficiency of preclinical retinal cell transplantation studies in rodents and other animal models.

Translational Relevance

By allowing longitudinal evaluation of the same animal over time, and providing quantifiable biomarkers, non-invasive multimodal imaging improves the efficiency of retinal transplantation studies in animal models. Such assays will facilitate the development of cell therapy for retinal diseases.