Comparison of the prognostic value of cardiac iodine-123 metaiodobenzylguanidine imaging and heart rate variability in patients with chronic heart failure A prospective study

AbstractObjectivesWe sought to prospectively compare the prognostic value of cardiac iodine-123 (I-123) metaiodobenzylguanidine (MIBG) imaging with that of heart rate variability (HRV) in patients with mild-to-moderate chronic heart failure (HF).BackgroundCardiac I-123 MIBG imaging, which reflects cardiac adrenergic nerve activity, provides prognostic information on chronic HF patients. Reduced HRV, indicating derangement in cardiac autonomic control, was also reported to be associated with a poor prognosis in chronic HF patients.MethodsAt study entry, I-123 MIBG imaging and 24-h Holter monitoring were performed in 65 chronic HF outpatients with a radionuclide left ventricular ejection fraction <40%. The cardiac MIBG heart to mediastinum ratio (H/M) and washout rate (WR) were obtained from MIBG imaging. The time and frequency domain parameters of HRV were calculated from 24-h Holter recordings.ResultsAt a mean follow-up of 34 ± 19 months, WR (p < 0.0001), H/M on the delayed image (p = 0.01), and normalized very-low-frequency power (n-VLFP) (p = 0.047) showed a significant association with the cardiac events (sudden death in 3 and hospitalization for worsening chronic HF in 10 patients) on univariate analysis. Multivariate analysis revealed that WR was the only independent predictor of cardiac events, although the predictive accuracy for the combination of abnormal WR and n-VLFP significantly increased, compared with that for abnormal WR (82% vs. 66%, p < 0.05).ConclusionsCardiac MIBG WR has a higher prognostic value than HRV parameters in patients with chronic HF. The combination of abnormal WR and n-VLFP would be useful to identify chronic HF patients at a higher risk of cardiac events

Glucose-stimulated single pancreatic islets sustain increased cytosolic ATP levels during initial Ca(2+) influx and subsequent Ca(2+) oscillations.

インスリン分泌における重要因子が変動する様子を可視化 -蛍光タンパク質センサーを用いたライブイメージング法で-. 京都大学プレスリリース. 2014-01-30.In pancreatic islets, insulin secretion occurs via synchronous elevation of Ca(2+) levels throughout the islets during high glucose conditions. This Ca(2+) elevation has two phases: a quick increase, observed after the glucose stimulus, followed by prolonged oscillations. In these processes, the elevation of intracellular ATP levels generated from glucose is assumed to inhibit ATP-sensitive K(+) channels, leading to the depolarization of membranes, which in turn induces Ca(2+) elevation in the islets. However, little is known about the dynamics of intracellular ATP levels and their correlation with Ca(2+) levels in the islets in response to changing glucose levels. In this study, a genetically encoded fluorescent biosensor for ATP and a fluorescent Ca(2+) dye were employed to simultaneously monitor the dynamics of intracellular ATP and Ca(2+) levels, respectively, inside single isolated islets. We observed rapid increases in cytosolic and mitochondrial ATP levels after stimulation with glucose, as well as with methyl pyruvate or leucine/glutamine. High ATP levels were sustained as long as high glucose levels persisted. Inhibition of ATP production suppressed the initial Ca(2+) increase, suggesting that enhanced energy metabolism triggers the initial phase of Ca(2+) influx. On the other hand, cytosolic ATP levels did not fluctuate significantly with the Ca(2+) level in the subsequent oscillation phases. Importantly, Ca(2+) oscillations stopped immediately before ATP levels decreased significantly. These results might explain how food or glucose intake evokes insulin secretion and how the resulting decrease in plasma glucose levels leads to cessation of secretion

Pathophysiological evaluations of initial plaque development after heart transplantation via serial multimodality imaging and cytokine assessments

Background: Detailed morphological characteristics of de novo and donor-transmitted plaques and the association of serum T-lymphocyte cytokine levels with plaque progression of coronary allograft vasculopathy within 1 year after heart transplantation are unknown. Methods: In this retrospective analysis of data in a prospectively maintained database, 40 heart transplant recipients were included. We performed serial 3 vessel optical coherence tomography and intravascular ultrasound analyses, at the 8 week (baseline) and 12 month post-transplantation follow-ups, and serum cytokine measurements (n = 23). The correlation between serum cytokines and Δplaque burden (between baseline and follow-up) was evaluated depending on plaque morphology. Results: Thirteen de novo plaques (maximum intimal thickness ≥0.5 mm at the 12 month follow-up without plaques at baseline) were identified in 8 recipients, and 31 donor-transmitted plaques (maximum intimal thickness ≥0.5 mm at baseline) were detected in 17 recipients. Compared with donor-transmitted plaques, the Δplaque burden in the de novo plaques, with mainly fibrous morphology, was high (38.8% [29.6%–41.2%] vs 8.7% [1.33%–13.6%], p < 0.001). Stratification of the morphology of donor-transmitted plaques revealed that the Δplaque burden in fibrous plaques (10.6% [7.0%–18.0%]) was similar to that in fibroatheroma (10.3% [8.7%–23.8%]). Serum interleukin-31 levels at baseline correlated with fibrous plaque proliferation (r = 0.73, p = 0.007) even under immunosuppressive conditions, whereas other cytokines (interleukin-1β, interleukin-17, and interferon-gamma) were mostly undetectable. Conclusions: Intimal fibrous proliferation contributed to the progression of donor-transmitted and de novo plaques. Serum interleukin-31 levels at baseline may contribute to intimal fibrous proliferation within 1 year after heart transplantation.Shiraki T., Ichibori Y., Ohtani T., et al. Pathophysiological evaluations of initial plaque development after heart transplantation via serial multimodality imaging and cytokine assessments. Journal of Heart and Lung Transplantation 41, 877 (2022); https://doi.org/10.1016/j.healun.2022.03.007