Seattle Proportional Risk Model in GISSI-HF: Estimated Benefit of ICD in Patients with EF less than 50%: Estimated Benefit of ICD in EF <50.

BACKGROUND: The Seattle Proportional Risk Model (SPRM) estimates the proportion of sudden cardiac death (SCD) in heart failure (HF) patients, identifying those most likely to benefit from implantable cardioverter-defibrillator (ICD) therapy (those with ≥50% estimated proportion of SCD). The GISSI-HF trial tested fish oil and rosuvastatin in HF patients. We used the SPRM to evaluate its accuracy in this cohort in predicting potential ICD benefit in patients with EF ≤50% and an SPRM-predicted proportion of SCD either ≥50% or <50%. METHODS: The SPRM was estimated in patients with EF ≤50% and in a logistic regression model comparing SCD with non-SCD. RESULTS: We evaluated 6,750 patients with EF ≤50%. There were 1,892 all-cause deaths, including 610 SCDs. Fifty percent of EF ≤35% patients and 43% with EF 36% to 50% had an SPRM of ≥50%. The SPRM (OR: 1.92, P < 0.0001) accurately predicted the risk of SCD vs non-SCD with an estimated proportion of SCD of 44% vs the observed proportion of 41% at 1 year. By traditional criteria for ICD implantation (EF ≤35%, NYHA class II or III), 64.5% of GISSI-HF patients would be eligible, with an estimated ICD benefit of 0.81. By SPRM >50%, 47.8% may be eligible, including 30.2% with EF >35%. GISSI-HF participants with EF ≤35% with SPRM ≥50% had an estimated ICD HR of 0.64, comparable to patients with EF 36% to 50% with SPRM ≥50% (HR: 0.65). CONCLUSIONS: The SPRM discriminated SCD vs non-SCD in GISSI-HF, both in patients with EF ≤35% and with EF 36% to 50%. The comparable estimated ICD benefit in patients with EF ≤35% and EF 36% to 50% supports the use of a proportional risk model for shared decision making with patients being considered for primary prevention ICD therapy.

Plasma Ceramides and Sphingomyelins and Sudden Cardiac Death in the Cardiovascular Health Study.

Importance: Sphingolipids, including ceramides and sphingomyelins, may influence the pathophysiology and risk of sudden cardiac death (SCD) through multiple biological activities. Whether the length of the fatty acid acylated to plasma sphingolipid species is associated with SCD risk is not known. Objective: To determine whether the saturated fatty acid length of plasma ceramides and sphingomyelins influences the association with SCD risk. Design, Setting, and Participants: In this cohort study, multivariable Cox proportional hazards regression models were used to examine the association of sphingolipid species with SCD risk. The study population included 4612 participants in the Cardiovascular Health Study followed up prospectively for a median of 10.2 (IQR, 5.5-11.6) years. Baseline data were collected from January 1992 to December 1995 during annual examinations. Data were analyzed from February 11, 2020, to September 9, 2023. Exposures: Eight plasma sphingolipid species (4 ceramides and 4 sphingomyelins) with saturated fatty acids of 16, 20, 22, and 24 carbons. Main Outcome and Measure: Association of plasma ceramides and sphingomyelins with saturated fatty acids of different lengths with SCD risk. Results: Among the 4612 CHS participants included in the analysis (mean [SD] age, 77 [5] years; 2724 [59.1%] women; 6 [0.1%] American Indian; 4 [0.1%] Asian; 718 [15.6%] Black; 3869 [83.9%] White, and 15 [0.3%] Other), 215 SCD cases were identified. In adjusted Cox proportional hazards regression analyses, plasma ceramides and sphingomyelins with palmitic acid (Cer-16 and SM-16) were associated with higher SCD risk per higher SD of log sphingolipid levels (hazard ratio [HR] for Cer-16, 1.34 [95% CI, 1.12-1.59]; HR for SM-16, 1.37 [95% CI, 1.12-1.67]). Associations did not differ by baseline age, sex, race, or body mass index. No significant association of SCD with sphingolipids with very-long-chain saturated fatty acids was observed after correction for multiple testing (HR for ceramide with arachidic acid, 1.06 [95% CI, 0.90-1.24]; HR for ceramide with behenic acid, 0.92 [95% CI, 0.77-1.10]; HR for ceramide with lignoceric acid, 0.92 [95% CI, 0.77-1.09]; HR for sphingomyelin with arachidic acid, 0.83 [95% CI, 0.71-0.98]; HR for sphingomyelin with behenic acid, 0.84 [95% CI, 0.70-1.00]; HR for sphingomyelin with lignoceric acid, 0.86 [95% CI, 0.72-1.03]). Conclusions and Relevance: The findings of this large, population-based cohort study of SCD identified that higher plasma levels of Cer-16 and SM-16 were associated with higher risk of SCD. Future studies are needed to examine the underlying mechanism of these associations.

Coronary endothelial dysfunction: from pathogenesis to clinical implications.

Endothelial dysfunction (ED) has a substantial role in the pathogenesis of atherosclerosis and other vascular diseases. Multiple risk factors, including smoking, hyperlipiadaemia and diabetes, can have associated ED, which is correlated with cardiac events. Measurement of coronary artery endothelial function requires the use of invasive techniques to assess both epicardial coronary artery and microvascular beds. Peripheral vascular techniques and endothelial biomarkers can be used to indirectly assess coronary ED. In this review of coronary artery ED, we discuss the current state of the field, the techniques used to measure ED and its clinical implications.

Assessment of Plasma Phospholipid Very-Long-Chain Saturated Fatty Acid Levels and Healthy Aging.

Importance: Identifying novel factors that protect against age-related diseases and promote healthy aging is critical to public health. Higher levels of circulating very-long-chain saturated fatty acids (VLSFAs) are integrated biomarkers of diet and metabolism shown to have beneficial associations in cardiovascular disease and total mortality, but whether they are associated with overall healthy aging is unknown. Objective: To examine the association of circulating levels of 3 VLSFAs with unhealthy aging events, including incident chronic disease (cardiovascular disease, cancer, lung disease or severe kidney disease), physical dysfunction, and cognitive decline. Design, Setting, and Participants: This cohort study used 1992 to 2014 data from the Cardiovascular Health Study (CHS). The CHS is a multicenter, population-based study of cardiovascular disease among older adults. Among the 4559 CHS participants with available fatty acid data, 1879 participants who had an age-related event before their first measurement were excluded. Data analysis was performed in 2020. Main Outcomes and Measures: Plasma phospholipid VLSFA levels were measured by thin-layer chromatography followed by gas chromatography. The main outcome was the hazard ratio (HR) of an incident unhealthy aging event associated with serial measures of plasma arachidic acid, behenic acid, and lignoceric acid. Results: Among the 2680 study participants (976 men [36.4%]), the mean (SD) age was 74.7 (4.8) years old at entry. During a median (interquartile range) of 6.4 (2.9-12.9) years of follow-up, 2484 participants experienced an unhealthy event. Compared with the lowest quintile, levels of behenic acid in the highest quintile of the fatty acid distribution were associated with 15% lower risk of an unhealthy event (HR, 0.85; 95% CI, 0.74-0.97; P for trend = .01) after adjustment for demographic characteristics, lifestyle factors, and clinical conditions. In analogous comparisons, levels of lignoceric acid were similarly associated with 16% lower risk of an unhealthy event (HR, 0.84; 95% CI, 0.73-0.95; P for trend = .001). Conclusions and Relevance: These findings suggest that higher levels of circulating behenic acid and lignoceric acid are associated with lower risk of unhealthy aging events. These results highlight the need to explore determinants of circulating VLSFAs for potential novel efforts to promote healthy aging.

Reversible Blindness as Presenting Manifestation of Severe Diabetic Ketoacidosis.

The presenting symptoms of diabetic ketoacidosis (DKA) include abdominal pain, polyuria and nausea. Diabetes has well known chronic ocular complications like glaucoma, cataracts and retinopathy. We report a case of reversible blindness as a presenting manifestation of DKA that has been reported in literature only 3 times previously. Our objective is to highlight a rare manifestation of a common disease. A 59-year-old male presented with painless vision loss for 3 days and was found to have DKA. The blindness was completely reversed with insulin and bicarbonate treatment. The dramatic presentation and reversibility of blindness was found to be intimately tied with the pH of the patient's serum. Our report gives mechanistic insight for this interesting condition. Clinicians should be aware of reversible blindness as a complication of DKA. Timely correction of the severe acidosis and other metabolic disturbances of DKA may be instrumental in preventing permanent vision loss.

Cardiac Insulin Signaling Regulates Glycolysis Through Phosphofructokinase 2 Content and Activity.

BACKGROUND: The healthy heart has a dynamic capacity to respond and adapt to changes in nutrient availability. Diabetes mellitus disrupts this metabolic flexibility and promotes cardiomyopathy through mechanisms that are not completely understood. Phosphofructokinase 2 (PFK-2) is a primary regulator of cardiac glycolysis and substrate selection, yet its regulation under normal and pathological conditions is unknown. This study was undertaken to determine how changes in insulin signaling affect PFK-2 content, activity, and cardiac metabolism. METHODS AND RESULTS: Streptozotocin-induced diabetes mellitus, high-fat diet feeding, and fasted mice were used to identify how decreased insulin signaling affects PFK-2 and cardiac metabolism. Primary adult cardiomyocytes were used to define the mechanisms that regulate PFK-2 degradation. Both type 1 diabetes mellitus and a high-fat diet induced a significant decrease in cardiac PFK-2 protein content without affecting its transcript levels. Overnight fasting also induced a decrease in PFK-2, suggesting it is rapidly degraded in the absence of insulin signaling. An unbiased metabolomic study demonstrated that decreased PFK-2 in fasted animals is accompanied by an increase in glycolytic intermediates upstream of phosphofructokianse-1, whereas those downstream are diminished. Mechanistic studies using cardiomyocytes showed that, in the absence of insulin signaling, PFK-2 is rapidly degraded via both proteasomal- and chaperone-mediated autophagy. CONCLUSIONS: The loss of PFK-2 content as a result of reduced insulin signaling impairs the capacity to dynamically regulate glycolysis and elevates the levels of early glycolytic intermediates. Although this may be beneficial in the fasted state to conserve systemic glucose, it represents a pathological impairment in diabetes mellitus.

Decreased Mitochondrial Pyruvate Transport Activity in the Diabetic Heart: ROLE OF MITOCHONDRIAL PYRUVATE CARRIER 2 (MPC2) ACETYLATION.

Alterations in mitochondrial function contribute to diabetic cardiomyopathy. We have previously shown that heart mitochondrial proteins are hyperacetylated in OVE26 mice, a transgenic model of type 1 diabetes. However, the universality of this modification and its functional consequences are not well established. In this study, we demonstrate that Akita type 1 diabetic mice exhibit hyperacetylation. Functionally, isolated Akita heart mitochondria have significantly impaired maximal (state 3) respiration with physiological pyruvate (0.1 mm) but not with 1.0 mm pyruvate. In contrast, pyruvate dehydrogenase activity is significantly decreased regardless of the pyruvate concentration. We found that there is a 70% decrease in the rate of pyruvate transport in Akita heart mitochondria but no decrease in the mitochondrial pyruvate carriers 1 and 2 (MPC1 and MPC2). The potential role of hyperacetylation in mediating this impaired pyruvate uptake was examined. The treatment of control mitochondria with the acetylating agent acetic anhydride inhibits pyruvate uptake and pyruvate-supported respiration in a similar manner to the pyruvate transport inhibitor α-cyano-4-hydroxycinnamate. A mass spectrometry selective reactive monitoring assay was developed and used to determine that acetylation of lysines 19 and 26 of MPC2 is enhanced in Akita heart mitochondria. Expression of a double acetylation mimic of MPC2 (K19Q/K26Q) in H9c2 cells was sufficient to decrease the maximal cellular oxygen consumption rate. This study supports the conclusion that deficient pyruvate transport activity, mediated in part by acetylation of MPC2, is a contributor to metabolic inflexibility in the diabetic heart.

cAMP-dependent Protein Kinase (PKA) Signaling Is Impaired in the Diabetic Heart.

Diabetes mellitus causes cardiac dysfunction and heart failure that is associated with metabolic abnormalities and autonomic impairment. Autonomic control of ventricular function occurs through regulation of cAMP-dependent protein kinase (PKA). The diabetic heart has suppressed ß-adrenergic responsiveness, partly attributable to receptor changes, yet little is known about how PKA signaling is directly affected. Control and streptozotocin-induced diabetic mice were therefore administered 8-bromo-cAMP (8Br-cAMP) acutely to activate PKA in a receptor-independent manner, and cardiac hemodynamic function and PKA signaling were evaluated. In response to 8Br-cAMP treatment, diabetic mice had impaired inotropic and lusitropic responses, thus demonstrating postreceptor defects. This impaired signaling was mediated by reduced PKA activity and PKA catalytic subunit content in the cytoplasm and myofilaments. Compartment-specific loss of PKA was reflected by reduced phosphorylation of discrete substrates. In response to 8Br-cAMP treatment, the glycolytic activator PFK-2 was robustly phosphorylated in control animals but not diabetics. Control adult cardiomyocytes cultured in lipid-supplemented media developed similar changes in PKA signaling, suggesting that lipotoxicity is a contributor to diabetes-induced ß-adrenergic signaling dysfunction. This work demonstrates that PKA signaling is impaired in diabetes and suggests that treating hyperlipidemia is vital for proper cardiac signaling and function.

Phosphoprotein Detection on Protein Electroblot Using a Phosphate-Specific Fluorophore.

The reversible phosphorylation of phosphoproteins is a vital regulatory process for many cellular pathways. A reliable and simple fluorescent detection technique for phosphoproteins has been developed using a small-molecule organic fluorophore, Pro-Q Diamond dye. This was originally developed for use in gel staining, but a new formulation has allowed for its use in protein blotting. The dye binds noncovalently and selectively to the phosphate moiety, so proteins lacking phosphate groups and other macromolecules, such as DNA or RNA, are not detected. It uses a standard electrophoresis and electroblotting technique, which can blot the sample onto nitrocellulose membranes or polyvinylidene fluoride (PVDF). The electroblotting is followed by staining with the dye and destaining. The blot can then be read by multiple types of imaging devices such as a laser-based gel scanner. This process is compatible with matrix-assisted laser desorption time-of-flight mass spectrometry (MALDI-TOF-MS) and Edman sequencing. It can also be followed by standard chemiluminescent, colorimetric, and fluorogenic detection techniques used in immunoblotting.

Phosphoprotein detection on protein electroblot using a phosphate-specific fluorophore.

The reversible phosphorylation of phosphoproteins is a vital regulatory process for many cellular pathways. A reliable and simple fluorescent detection technique for phosphoproteins has been developed using a small-molecule organic fluorophore, Pro-Q Diamond dye. This was originally developed for use in gel staining, but a new formulation has allowed for its use in protein blotting. The dye binds noncovalently and selectively to the phosphate moiety, so proteins lacking phosphate groups and other macromolecules such as DNA or RNA are not detected. It uses a standard electrophoresis and electroblotting technique, which can blot the sample onto nitrocellulose membranes or polyvinylidene fluoride (PVDF). The electroblotting is followed by staining with the dye and destaining. The blot can then be read by multiple types of imaging devices such as a laser-based gel scanner. This process is compatible with matrix-assisted laser desorption time-of-flight mass spectrometry (MALDI-TOF-MS) and Edman sequencing. It can also be followed by standard chemiluminescent, colorimetric, and fluorogenic detection techniques used in immunoblotting.