Real-time cardiac magnetic resonance tissue characterisation for fibrosis assessment in aortic stenosis

Background

Myocardial fibrosis is a major determinant of outcome in aortic stenosis (AS). Novel fast real-time (RT) cardiac magnetic resonance (CMR) mapping techniques allow comprehensive quantification of fibrosis but have not yet been adequately validated against standard techniques and histology.

Methods

Patients with severe AS underwent CMR before (n=110) and left ventricular (LV) endomyocardial biopsy (n=46) at transcatheter aortic valve replacement (TAVR). Midventricular short axis native, post-contrast T1 and extracellular volume fraction (ECV) maps were generated using commercially available 5(3)3 MOLLI and RT single-shot inversion recovery fast low-angle shot (FLASH) with radial undersampling. ECV and LV mass were used to calculate LV matrix volumes. Variability and agreements were assessed between RT, MOLLI and histology using intraclass correlation coefficients, coefficients of variation and Bland Altman analyses.

Results

RT and MOLLI derived ECV were similar for myocardium (26.2 vs. 26.5, p=0.073) and inter-ventricular septum (26.2 vs. 26.5, p=0.216). MOLLI native T1 time was in median 20 ms longer compared to RT (p<0.001). Agreement between RT and MOLLI was best for ECV (ICC >0.91), excellent for post-contrast T1 times (ICC >0.81) and good for native T1 times (ICC >0.62). Diffuse collagen volume fraction by biopsies was in median 7.8%. ECV (RT r=0.345, p=0.039; MOLLI r=0.40, p=0.010) and LV matrix volumes (RT r=0.45, p=0.005; MOLLI r=0.43, p=0.007) were the only parameters associated with histology.

Conclusions

RT mapping offers precise T1 and ECV assessments with similar agreement with histology as compared to conventional MOLLI techniques. Single-shot real time techniques may be advantageous in sicker patients prone to dyspnoea or arrhythmia.

Funding Acknowledgement

Type of funding source: Foundation. Main funding source(s): German Research Foundation

Structural and functional reverse myocardial remodeling following transcatheter aortic valve replacement

Background

Myocardial reverse remodeling determines outcome in patients with severe aortic stenosis (AS) following transcatheter aortic valve replacement (TAVR). However, little is known about the interplay of myocardial function and structure after TAVR. Since cardiac magnetic resonance (CMR) imaging allows comprehensive quantification of both structure and function we aimed to assess changes in myocardial tissue composition and deformation before and following TAVR.

Methods

CMR imaging was performed in 40 prospectively enrolled patients with severe AS before and one year after TAVR. Myocardial function was characterized using volumetry and CMR-feature-tracking (FT) deformation imaging of left ventricular (LV) global longitudinal strain (GLS) and atrial function (atrial reservoir ES, conduit Ee and booster pump strain EA). Myocardial structure was assessed using T1 mapping and late gadolinium enhancement (LGE) analysis. LV cellular and matrix volumes were calculated based on extra cellular volume fraction (ECV) and LV mass. CMR-FT results were compared to a control group of twenty patients with normal biventricular function. Moreover, biomarkers (NT-proBNP), functional (six-minute-walking-test) and clinical status (NYHA, Minnesota LIVING WITH HEART FAILURE score) were determined at baseline and one-year follow-up.

Results

Regression of both cellular (−20.6%, p<0.001) and matrix volumes (−12.3%, p=0.003) and subsequently increased ECV (+9.0%, p=0.001) were documented one year after TAVR. Ventricular and atrial strains were impaired at baseline (GLS p=0.004, Es p<0.001, Ee p<0.001) and recovered during follow-up (GLS p<0.001, Es p=0.005, Ee p=0.001). These changes were paralleled by improvements in NYHA (p<0.001) and Minnesota (p<0.001) scores as well as decline in NT-proBNP levels (p=0.001). There was a significant association of LV fibrosis as defined by matrix volume and extent of LGE and ventricular and atrial functional impairment (correlation of matrix volume and: GLS r=0.57, p<0.001, Es r=−0.44, p=0.009; correlation of LGE%LV and: GLS r=0.41, p=0.015, Es: r=−0.4, p=0.02, and Ea: r=−0.41, p=0.02).

Conclusion

Regression of fibrosis and cellular hypertrophy determine improved myocardial function and recovery from heart failure following TAVR. Prognostic implications of the observed changes will need to be explored next to identify makers and therapeutic targets for optimized management of these patients.

Funding Acknowledgement

Type of funding source: Foundation. Main funding source(s): German Research Foundation (DFG, CRC 1002, D1)

[InterAtrial Shunt Device in diastolic heart failure]

All types of heart failure are associated with reduced cardiac output and/or increased left atrial (LA) pressure. In diastolic heart failure (heart failure with preserved ejection fraction [HFpEF]), the increased LA pressure plays a central role, leading to pulmonary venous hypertension (PVH) and increased pulmonary artery pressure. These pressure parameters are presumably decisive for the symptoms and mortally of heart failure, particularly of the diastolic form. This is the basis for treatment with an interarterial shunt to reduce LA pressure in patients with diastolic heart failure and PVH. At first glance, this appears paradoxical, since closure of an atrial septum defect serves to prevent increased pulmonary vascular resistance and paradoxical embolism. Prevention of increased pulmonary vascular resistance and paradoxical embolism is thus an essential aspect in the development of devices for establishing an interarterial shunt. Reports on the InterAtrial Shunt Device (IASD®) and the V‑Wave have been published, both of which can be implanted with a low risk and few complications. The V‑Wave device is equipped with a valve to prevent paradoxical embolisms. However, paradoxical embolisms were also not observed with the IASD®, and the valve of the V‑Wave exhibited considerable degenerative changes and valve closure. Hemodynamic and clinical data of patients with an IASD® or an open V‑Wave device demonstrated a sustained hemodynamic improvement. Physical performance capacity and quality of life were increased. Whether IASD® may be broadly applicable in patients with diastolic heart failure is currently under investigation. In selected highly symptomatic patients with diastolic heart failure and PVH, the IASD® is already in clinal use.

[Insufficient use of anticoagulants in geriatric in-patients with atrial fibrillation and flutter (corrected)]

INTRODUCTION

Anticoagulation for the prevention of cardioembolic events is highly effective, but largely underused in frail older patients with atrial fibrillation or flutter (AF). This study aimed at identifying characteristics associated with anticoagulation use or non-use and the most frequent complications of this therapy.

METHODS

Hospitalized geriatric patients treated in a one-year interval were retrospectively studied for the presence of AF and use or non-use of anticoagulation. The risk of stroke and the indication for permanent anticoagulation were assessed using the CHA2DS2-VASc score.

RESULTS

In 451 of 1167 hospitalized patients (38.6%) there was a clear indication for anticoagulation. The most frequent indication for anticoagulation was AF in 381 patients (84.5% of 451 patients). Of these 381 patients, a strong indication for anticoagulation, based on CHA2DS2-VASc score, was identified in 379 patients. Of these patients, 200 (52.8%) did and 179 (47.2%) patients did not receive anticoagulation. 153 patients (40.4%) received antiplatelet therapy. 26 patients (6.7%) received neither anticoagulants nor antiplatelet therapy. The most common reason for non-implementation of anticoagulation was a high risk of falls in 93 patients (52%) of 179 patients without antocoagulation. The most frequent complications of anticoagulation were small hemorrhages without serious consequences in 8 cases. 4 patients suffered from serious bleedings.

CONCLUSION

Almost half of our geriatric population did not receive anticoagulation despite a clear indication. Antiplatelet therapy use was associated with anticoagulation non-use.

[Diabetes increases short- and long-term mortality after transcatheter aortic valve implantation (TAVI)]

BACKGROUND AND AIM

Long-term mortality after transcatheter aortic valve implantation (TAVI) in elderly patients with abundant comorbidities is considerable. We aimed to determine the impact of diabetes on short- and long-term mortality after TAVI.

METHODS

Our study includes 300 consecutive patients (mean age, 82 ± 5 years) who underwent TAVI (158 transapical, 142 transfemoral procedures). All patients were followed by regular telephone contacts. 36% suffered from diabetes.

RESULTS

Diabetes could be identified as significant predictor of short- and long-term mortality after TAVI. In diabetic patients, 30-day-mortality was 2,5 fold elevated (18.3% vs. 7.3%, p = 0.004). Furthermore, they were at significantly higher risk of peri-interventional stroke (p = 0.04), stage 3 acute kidney injury (p = 0.003), and prolonged ventilation (p = 0.01). Even after successful TAVI and discharge from hospital, long-term mortality was significantly elevated in diabetic patients (56% vs. 30%, p < 0.0001). Of note, 25% of diabetic vs. only 8% of non-diabetic patients died from cardiac causes during follow-up, suggesting that TAVI is not able to reduce cardiac-related mortality risk in diabetic patients to the same extent as in non-diabetics.

CONCLUSION

Diabetes represents a powerful predictor of adverse early and late outcome after TAVI. These findings should be incorporated into the assessment of the risk-to-benefit ratio of TAVI in diabetic patients.

Hotline update of clinical trials and registries presented at the American College of Cardiology Congress 2010: ACCORD, INVEST, NAVIGATOR, RACE II, SORT OUT III, CSP-474, DOSE, ASPIRE and more

This article gives an overview on a number of novel clinical trials in the field of cardiovascular medicine, which were presented during the Late Breaking Clinical Trial Sessions at the 59th annual meeting of the American College of Cardiology in Atlanta, USA, from 14th March to 16th March 2010. The data were presented by leading experts in the field with relevant positions in the trials. These comprehensive summaries should provide the readers with the most recent data on diagnostic and therapeutic developments in cardiovascular medicine similar as previously reported (Schirmer SH, van der Laan AM, Bohm M, Mahfoud F in Clin Res Cardiol 98:691-699, 2009; Maier LS, Schirmer SH, Walenta K, Jacobshagen C, Bohm M in Clin Res Cardiol 98:413-419, 2009).

Extracellular nucleotides regulate cellular functions of podocytes in culture

Extracellular nucleotides are assumed to be important regulators of glomerular functions. This study characterizes purinergic receptors in podocytes. The effects of purinergic agonists on electrophysiological properties and the intracellular free Ca(2+) concentration of differentiated podocytes were examined with the patch-clamp and fura 2 fluorescence techniques. mRNA expression of purinergic receptors was investigated by RT-PCR. Purinergic agonists depolarized podocytes. Purinergic agonists similarly increased intracellular free Ca(2+) concentration of podocytes. The rank order of potency of various nucleotides on membrane voltage and free cytosolic calcium concentration was UTP approximately UDP > [adenosine 5'-O-(3-thiotriphosphate) (ATP-gamma-S)] > ATP > 2-methylthioadenosine 5'-triphosphate (2-MeS-ATP) > 2'- and 3'-O-(4-benzoylbenzoyl)-adenosine 5'-triphosphate (BzATP) > ADP-beta-S. alpha,beta-Me-ATP was without effect. In the presence of UTP, BzATP did not cause an additional depolarization of podocytes. Incubation of cells with ATP or BzATP did not induce lactate dehydrogenase release. In RT-PCR studies, mRNAs of the P2Y(1), P2Y(2), P2Y(6), and P2X(7) receptors were detected within glomeruli and podocytes. The data indicate that extracellular nucleotides modulate podocyte function mainly by an activation of both P2Y(2) and P2Y(6) receptors.