What is the most useful imaging parameter to explore the prognostic value of the right ventricular function at the time of multimodality cardiovascular imaging?

BACKGROUND: Right ventricular (RV) function is a powerful independent predictor of adverse heart failure outcomes. The aim of this study was to compare the predictive value of main RV systolic imaging parameters for outcome. METHODS: Seventy-nine patients underwent comprehensive cardiovascular imaging modalities including transthoracic echocardiography, cardiac magnetic resonance (CMR) imaging, and tomographic equilibrium radionuclide ventriculography (ERV) for the assessment of RV function. The composite primary endpoint (CPE) was defined by the occurrence of death, heart transplantation, implantation of a left ventricular assist device, or new-onset acute heart failure. RESULTS: During a mean follow-up of 13 ± 9 months, 15 (19%) patients reached the CPE. The areas under the receiver operator characteristic curves for the prediction of the CPE were 0.922 (P < .001), 0.913 (P < .001), 0.906 (P < .001), 0.849 (P = .002), 0.837 (P = .003), 0.799 (P = .009), 0.792 (P = .011), 0.753 (P = .026), 0.720 (P = .053), and 0.608 (P = .346) for integral systolic S' wave tricuspid annular velocity, RV free wall longitudinal strain (RVFWLS), RV fractional area change, tricuspid annular plane systolic excursion, RV ejection fraction (RVEF) by CMR using the 4-chamber slices, peak systolic S' wave tricuspid annular velocity, RVEF by CMR using short-axis slices, RVEF by ERV, RV myocardial performance index, and RV myocardial acceleration during isovolumic contraction, respectively. CONCLUSION: Echocardiographic parameters, and particularly integral systolic S' wave tricuspid annular velocity and RVFWLS, have the best prognostic performance.

Sirtuin 1 activation attenuates cardiac fibrosis in a rodent pressure overload model by modifying Smad2/3 transactivation.

Aims: Transforming growth factor ß1 (TGF-ß1) is a prosclerotic cytokine involved in cardiac remodelling leading to heart failure (HF). Acetylation/de-acetylation of specific lysine residues in Smad2/3 has been shown to regulate TGF-ß signalling by altering its transcriptional activity. Recently, the lysine de-acetylase sirtuin 1 (SIRT1) has been shown to have a cardioprotective effect; however, SIRT1 expression and activity are paradoxically reduced in HF. Herein, we investigate whether pharmacological activation of SIRT1 would induce cardioprotection in a pressure overload model and assess the impact of SIRT1 activation on TGF-ß signalling and the fibrotic response. Methods and results: Eight weeks old male C57BL/6 mice were randomized to undergo sham surgery or transverse aortic constriction (TAC) to induce pressure overload. Post-surgery, animals were further randomized to receive SRT1720 or vehicle treatment. Echocardiography, pressure-volume loops, and histological analysis revealed an impairment in cardiac function and deleterious left ventricular remodelling in TAC-operated animals that was improved with SRT1720 treatment. Genetic ablation and cell culture studies using a Smad-binding response element revealed SIRT1 to be a specific target of SRT1720 and identified Smad2/3 as a SIRT1 specific substrate. Conclusion: Overall, our data demonstrate that Smad2/3 is a specific SIRT1 target and suggests that pharmacological activation of SIRT1 may be a novel therapeutic strategy to prevent/reverse HF via modifying Smad activity.

Impaired cardiac anti-oxidant activity in diabetes: human and correlative experimental studies.

Increased reactive oxygen species (ROS) are traditionally viewed as arising from the metabolic flux of diabetes, although reduction in the activity of anti-oxidant systems has also been implicated. Among the latter is the major thiol reducing thioredoxin system, the activity of which may be diminished by high glucose-induced expression of its endogenous inhibitor, thioredoxin interacting protein (TxnIP). We assessed TxnIP mRNA/protein expression along with thioredoxin activity in human right atrial biopsy specimens from subjects with and without diabetes undergoing coronary artery grafting. In correlative experimental studies, we examined TxnIP expression in both type 1 and type 2 rodent models of diabetic cardiomyopathy. Finally, we used in vitro gene silencing to determine the contribution of changes in TxnIP abundance to the high glucose-induced reduction in thioredoxin activity. In human right atrial biopsies, diabetes was associated with a >30-fold increase in TxnIP gene expression and a 17 % increase in TxnIP protein expression (both p < 0.05). This was associated with a 21 % reduction in thioredoxin activity when compared to human non-diabetic cardiac biopsy samples (all p < 0.05). In correlative animal studies, both type 1 and type 2 diabetic rats demonstrated a significant increase in TxnIP mRNA and reduction in thioredoxin activity when compared to non-diabetic animals (all p < 0.05). This was associated with a significant increase in ROS (p < 0.05 when compared with control). In cultured cardiac myocytes, high glucose increased ROS and TxnIP mRNA expression, in association with a reduction in thioredoxin activity (p < 0.01). These findings were abrogated by TxnIP small interfering RNA (siRNA). Scrambled siRNA had no effect upon ROS or TxnIP expression. High glucose reduces thioredoxin activity and increases ROS via TxnIP overexpression. These findings suggest that impaired thiol reductive capacity, through altered TxnIP expression, contributes to increased ROS in the diabetic heart.