PET/CT-identified atrial hypermetabolism is an index of atrial inflammation in patients with atrial fibrillation

BACKGROUND

Although atrial inflammation has been implicated in the pathophysiology of atrial fibrillation (AF), the identification of atrial inflammation remains challenging. We aimed to establish a positron emission tomography/computed tomography (PET/CT) protocol with 18Fluor-labeled fluorodeoxyglucose (18F-FDG) for the detection of atrial hypermetabolism as surrogate for inflammation in AF.

METHODS

We included n = 75 AF and n = 75 non-AF patients undergoing three common PET/CT protocols (n = 25 per group) optimized for the detection of (a) inflammation and (b) malignancy in predefined fasting protocols, and (c) cardiac viability allowing for maximized glucose uptake. 18F-FDG-uptake was analyzed in predefined loci.

RESULTS

Differences of visual atrial uptake in AF vs non-AF patients were observed in fasting (inflammation [13/25 vs 0/25] and malignancy [10/25 vs 0/25]) protocols while viability protocols showed non-specific uptake in both the groups. In the inflammation protocol, AF patients showed higher uptake in the right atrium [(SUVmax: 2.5 ± .7 vs 2.0 ± .7, P = .01), atrial appendage (SUVmax: 2.4 ± .7 vs 2.0 ± .6, P = .03), and epicardial adipose tissue (SUVmax: 1.4 ± .5 vs 1.1 ± .4, P = .04)]. Malignancy and viability protocols failed to differentiate between AF and non-AF.

CONCLUSION

Glucose uptake suppression protocols appear suitable in detecting differential atrial 18F-FDG uptake between AF and non-AF patients. Imaging-based assessment of inflammation might help to stratify AF patients offering individualized therapeutic approaches.

Pulsed field ablation for atrial fibrillation: acute procedural efficacy and safety of an initial German multicenter experience

Background

Pulsed field ablation (PFA) is a novel non-thermal energy source to conduct catheter ablation of atrial fibrillation (AF). However, real-world multi-center data regarding acute procedural efficacy and safety is sparse.

Purpose

To study acute procedural success and safety in patients undergoing PFA for catheter ablation of AF in a multicenter registry.

Methods

Consecutive paroxysmal and persistent AF patients undergoing PFA-based catheter ablation using a multispline catheter were enrolled. The cohort included first and repeat ablation procedures. Procedural parameters, acute success and in-hospital safety were evaluated. A follow-up of all patients was conducted.

Results

Five German centers enrolled a total of 154 patients undergoing PFA in this study. Mean age was 68±12 years, median CHA2DS2-VASc Score was 3 (Q1-Q3: 2–4).

Patients suffered from paroxysmal AF (n=55; 36%), persistent AF (n=93; 60%) and consecutive atrial tachycardias (AT) due to previous CA (n=6; 4%).

The median left atrial (LA) PFA and total procedure times were 33 (Q1-Q3: 24–53) and 90 (Q1-Q3: 73–116) minutes, respectively. Mean LA PFA fluoroscopy and total fluoroscopy times were 12.1±5.5 and 20.2±8.7 minutes. Of all 154 procedures, 130 (84%) were index ablation procedures with isolation of pulmonary veins (PVI) only and 24 (16%) were repeat procedures (including re-PVI and ablation of consecutive AT).

Acute PV reconnection following primary PVI and the initial set of PFA-applications was found in 20/130 (15%) patients, necessitating additional PFA ablation. Finally, successful PFA-guided PVI was achieved in all patients.

Additional PFA lesion sets (including LA posterior wall isolation, anterior ablation, mitral isthmus ablation) were applied in 17/154 (11%) patients.

Complications occurred in a total of 6/154 (3.8%) patients (including three groin site complications, two pericardial tamponades, one transient coronary spasm without sequela). The follow up data is still being assessed and will be provided by the time of the ESC 2022 meeting.

Conclusion

PFA performed in patients with atrial fibrillation demonstrates high acute procedural success rates and a favorable safety profile in this first real-world multicenter registry.

Funding Acknowledgement

Type of funding sources: None.

[Catheter ablation : Developments and technique selection]

Atrial fibrillation (AF) is the most common arrhythmia and an important risk factor for the occurrence of cardiovascular events. According to current guidelines, rhythm-controlling therapy is recommended only for symptomatic AF. Even in symptomatic AF there is still only a class IIa-recommendation for catheter ablation as initial therapy in paroxysmal AF. Meanwhile, current studies have shown an advantage of the early rhythm control compared to a rate control, as well as a benefit of catheter ablation compared to antiarrhythmic drug (AAD) treatment. The gold standard of catheter ablation for AF therapy is pulmonary vein isolation, which has been mainly radiofrequency-based in the past. However, cryoablation as a first-line therapy of paroxysmal AF is increasingly gaining importance, as the latest studies showed shorter procedure times, lower reintervention rates and improved life quality after cryoablation. Nevertheless, using these standard techniques, the risk of adverse events is still given through collateral damage. The field high-power short duration ablation is currently topic of ongoing AF research, which describes a radiofrequency ablation with higher energy levels, given over shorter duration, with a consecutive lower recurrence rate as well as procedure time. The new ablation techniques also include the pulsed field ablation, which allows ablation through very fast delivery of electrical pulses and causes isolated damage to myocardial cells without collateral damage. This promising technique passed the efficiency and safety testing in preclinical studies. To validate this technique further randomized trials are needed.

Initial experience and follow up on the PolarX cryoablation system compared to the established Arctic Front cryoablation system in PVI ablations

Introduction

Pulmonary vein isolation (PVI) with cryoablation was shown to be comparable to radiofrequency ablation (RF) in terms of safety and outcome for patients with atrial fibrillation (AF), so that both techniques are recommended equally by the current guidelines. A new cryoablation system PolarX® was introduced in 2020. We analysed the first patients, who underwent ablation with the new system with respect to procedural and safety outcome and evaluated the freedom from arrhythmia occurrence in the first 6 months compared to patients treated with the established Arctic Front Advance® cryoablation system.

Methods

We included the consecutive 44 patients who underwent cryoablation with the new PolarX® cryoablation system (28mm) and 24 patients who underwent cryoablation with the established Arctic Front Advance® cryoablation system (28mm) for paroxysmal AF. We retrospectively analysed baseline characteristics, procedural- and safety data. In 5 patients of each group an additional high-density 3D-mapping was performed, evaluating the scar-area after cryoablation in both groups (figure 1A+B). After 6 months the freedom of AF (by 7d-Holter-ECG) was evaluated in both groups.

Results

Baseline, procedural characteristics and results are listed in table 1. Mean total procedure duration (“door-to-door-time”) was significantly shorter in the PolarX group compared to the Arctic-Front group (136±34min vs. 163±43min; p<0.05). Number of freezes required to achieve isolation of all pulmonary veins (PVs) and cumulative freezing time was comparable in both groups. Minimal achieved temperatures were significantly lower in the PolarX group vs. ArcticFront group. The scar-area analyzed by 3D-mapping post ablation did not differ in the two groups. Complication rates as well as clinical outcome (freedom from AF) were low and did not differ in the Kaplan-Meier analysis (table 1; figure 1C).

Conclusion

Based on these initial results, cryoablation with the PolarX cryoballoon seems to be comparably effective and safe, with a significantly shorter procedure time and significantly lower achieved temperatures. Nevertheless, future controlled trials with a longer follow-up period will be necessary to evaluate long-term effectiveness.

Funding Acknowledgement

Type of funding sources: None.

Concomitant real-time measurement and correlation of contact force to baseline local impedance and local impedance drops in RF ablation of left and right atrial procedures

Introduction

Radiofrequency (RF) ablation is performed in various arrhythmias. Still, arrhythmia recurrence is a challenging problem, not only in atrial fibrillation (AF). One reason for arrhythmia recurrence is suspected to be due to remaining gaps. Measurement of local impedance (LI) and change of LI during RF application can be used as a predictor and surrogate for successful ablation. Another tool, used for the last couple of years, estimating sufficient tissue contact is provided by catheters with real-time contact force (CF) measurement. The new INTELLANAV STABLEPOINT™ catheter by Boston Scientific was recently introduced combing both strategies. We sought to investigate the parallel measurement and correlation of LI and CF in real-time during left atrial (LA) and right atrial (RA) procedures.

Methods

We included the first n=20 patients who underwent LA ablation for AF or atypical atrial flutter and n=7 patients who underwent RA procedures for atrial flutter or atrial tachycardia and analysed retrospectively procedural data. For every RF delivery RF duration, CF, baseline LI, minimal LI, LI drop, as well as minimal LI and LI drop after 5 and 10 sec was documented. Only RF deliveries with stable contact (ablation without delay) were included. We then correlated baseline LI to LI drop (maximum, after 5 sec, after 10 sec) and to the documented CF at baseline.

Results

A total of 27 procedures was analysed. In total, 777 RF deliveries (663 in LA, 114 in RA) were documented with a mean RF duration of 21.7 sec. Mean baseline LI was 148.4 Ω, minimal LI 130.6Ω, LI after 5 sec 135.0 Ω and LI after 10sec 132.5 Ω. Mean complete LI drop was 17.8 Ω (13.4 Ω after 5 sec, 15.8 Ω after 10 sec). Mean CF was 15.5g. We could see a significant positive correlation between average CF and LI drop (p<0.01) (figure 1A), as well as between average CF and LI drop after 5 sec (p<0.01) and after 10 sec (p<0.01). Also, for baseline LI we could see a significant strong positive correlation to LI drop (p<0.001) (figure 1B), LI drop after 5 sec (p<0.001) and after 10 sec (p<0.001). Baseline LI did not correlate to average CF. Baseline LI was significantly higher in RA, when compared to LA (152.5Ω vs. 147.7Ω; p<0.05). LI drop did not differ between RA and LA procedures (17.8Ω vs. 17.7Ω), whereas mean RF duration per RF application was significantly longer in LA compared to RA procedures (22.8sec vs. 15.3sec; p<0.001) and applied CF was also higher in LA compared to RA procedures (16.0Ω vs. 12.8Ω; p<0.001).

Conclusion

Parallel real-time measurement of LI and CF is providing further insights into ablation biophysics. Based on these results the CF values might provide a prediction of subsequent lesion formation. A combination with LI measurement seems to be useful to prevent insufficient lesions, predisposing to gap formation and associated with arrhythmia recurrence, but also to potentially guarantee a higher safety by visualizing the applied CF and consecutive LI drop.

Funding Acknowledgement

Type of funding sources: None. Figure 1

Increased FDG uptake in AF individuals suggesting atrial inflammation visualized by FDG PET/CT with glucose uptake suppression protocols

Background

Pathophysiology of atrial fibrillation (AF) is multifactorial. Attention has been drawn towards atrial inflammation underlying arrhythmogenic remodeling. The aim of our study was to evaluate if a specific preparation protocol for positron emission tomography/computed tomography (PET/CT) with 18Fluor-labelled fluorodeoxyglucose (18F-FDG) was capable of detecting atrial hypermetabolism as surrogate for inflammation in AF, with the specific hypothesis that protocols specifically aiming to suppress physiologic glucose metabolism (fasting protocols: inflammation and malignancy preparation) were superior to non-fasting protocols.

Methods

We conducted a single-center study including n=75 patients with a history of AF and n=75 controls without AF (matched for age, sex and left ventricular systolic function) undergoing three different preparation protocols (each n=25 per group): i.) inflammation, ii.) malignancy and iii.) viability protocol before 18F-FDG-PET/CT. We performed visual analysis of local detectable atrial uptake (figure 1A) and assessed quantitative uptake in predetermined loci of the atria and endocrine adipose tissue (EAT), using maximum standardized uptake values (SUVmax) and target to background ratios (TBR).

Results

Our analysis of visual atrial 18F-FDG uptake revealed that atrial uptake was exclusively observed in AF patients using the malignancy (13/25 patients) and inflammation (10/25 patients) protocol, while the viability preparation revealed atrial uptake both in AF (n=6 patients) and non-AF patients (n=5 patients).

With respect to quantitative measures between AF and non-AF individuals using the inflammation protocol, patients with AF showed significantly higher uptake values in the right atrium (SUVmax: 2.54±0.75 vs. 2.03±0.66, p=0.01); TBR 1.51±0.44 vs. 1.18±0.20, p<0.01), right atrial appendage (SUVmax: 2.44±0.71 vs. 2.02±0.64, p=0.03; TBR: 1.47±0.47 vs. 1.20±0.26, p=0.02) and also in EAT (SUVmax: 1.39±0.46 vs. 1.13±0.40, p=0.04), figure 1B. Despite a trend of higher tracer uptake related to the presence of AF in left atrial structures, no statistical significances could be observed between AF and non-AF individuals.

Conclusion

This retrospective study demonstrates that protocols specifically designed to suppress physiologic glucose uptake seem to be superior in detecting atrial FDG uptake, which could be indicative of atrial inflammation in AF patients. Based on our results the right atrium seems to be more affected from these changes. These results point towards a potential role of right atrial inflammatory processes in AF pathophysiology besides the established left atrial ectopic triggers.

Funding Acknowledgement

Type of funding sources: None.

Visualization of fibroblast activation after myocardial infarction using 68Ga-FAPI-PET

Introduction

Fibroblast activation protein (FAP) alpha specifically expressed by activated fibroblasts has been shown to be significantly involved in processes of tissue healing after injury, including fibrotic remodeling after myocardial infarction (MI). Positron-emission tomography (PET) with the tracer FAP-inhibitor (FAPI) is a novel diagnostic tool primarily described in oncologic patients for tumor stroma detection. We present data from a pilot study investigating patients after MI who underwent subsequent 68Ga-FAPI-PET for assessment of potential FAP-related myocardial remodeling.

Methods

In this retrospective study we analyzed a cohort of 10 post-MI patients who underwent 68Ga-FAPI-PET imaging with respect to cardiac tracer pattern. Standardized maximum and mean uptake values and total volume of tracer enrichment (fibroblast activation volume, FAV) of the infarcted area were calculated. A visual grading scale was established to assess the level of agreement between maximum localized tracer uptake and segments belonging to the supply area of the culprit vessel. Tracer uptake was correlated to clinical variables, with readers blinded to the clinical characteristics.

Results

Focal 68Ga-FAPI uptake was detected in all 10/10 patients after MI. According to our grading system for visual agreement of polar map segments and culprit lesion, we observed a very good (in 37.5% of patients) and a moderate (62.5% of patients) match between tracer uptake and the culprit lesion, respectively. We demonstrated a negative correlation of FAV uptake and left ventricular systolic function (R2=−0.69, p<0.05) and a very strong positive correlation of FAV and peak creatinine kinase level (R2=0.90, p<0.01).

Conclusion

Increased myocardial 68Ga-FAPI uptake, serving as a surrogate for FAP expression after MI, corresponds well to the supply area of the culprit coronary vessel as well as to biomarker levels of myocardial injury. This imaging technique represents a highly promising, novel bio-signal in the assessment of myocardial injury and consecutive remodeling. Large controlled studies are warranted to further evaluate the prognostic impact of this novel imaging technique.

Funding Acknowledgement

Type of funding sources: None.

Cardiac fibroblast activation detected by Ga-68 FAPI PET imaging as a potential novel biomarker of cardiac injury/remodeling

BACKGROUND

Fibroblast activation protein (FAP) as a specific marker of activated fibroblasts can be visualized by positron emission tomography (PET) using Ga-68-FAP inhibitors (FAPI). Gallium-68-labeled FAPI is increasingly used in the staging of various cancers. In addition, the first cases of theranostic approaches have been reported. In this work, we describe the phenomenon of myocardial FAPI uptake in patients who received a Ga-68 FAPI PET for tumor staging.

METHOD AND RESULTS

Ga-68 FAPI PET examinations for cancer staging were retrospectively analyzed with respect to cardiac tracer uptake. Standardized uptake values (SUV) were correlated to clinical covariates in a univariate regression model. From 09/2018 to 11/2019 N = 32 patients underwent FAPI PET at our institution. Six out of 32 patients (18.8%) demonstrated increased localized myocardial tracer accumulation, with remote FAPI uptake being significantly higher in patients with vs without localized focal myocardial uptake (SUVmax 2.2 ± .6 vs 1.5 ± .4, P < .05 and SUVmean 1.6 ± .4 vs 1.2 ± .3, P < .05, respectively). Univariate regression demonstrated a significant correlation of coronary artery disease (CAD), age and left ventricular ejection fraction (LVEF) with remote SUVmean uptake, the latter with a very strong correlation with remote uptake (R2 = .74, P < .01).

CONCLUSION

Our study indicates an association of CAD, age, and LVEF with FAPI uptake. Further studies are warranted to assess if fibroblast activation can be reliably measured and may be used for risk stratification regarding early detection or progression of CAD and left ventricular remodeling.

RNA-seq profiling of the atrial transcriptome reveals gender-specific patterns and interactions with atrial fibrillation and heart failure

Funding Acknowledgements

Type of funding sources: Public grant(s) – EU funding. Main funding source(s): TRAIN-HEART Innovative Training Network, funded by the European Union’s Horizon 2020 research and innovation program (under the Marie Sklodowska-Curie grant agreement no. 813716) Characterizing Atrial fibrillation by Translating its Causes into Health Modifiers in the Elderly (CATCH ME), funded by the European Union’s Horizon 2020 research and innovation program (under the grant agreement no. 633196)

Background

Atrial fibrillation (AF) is the most common cardiac arrhythmia and is associated with heart failure (HF) and stroke. Clinical and experimental data from previous studies suggest gender differences in mechanisms and phenotypes of AF: women may have more atrial fibrosis, worse outcomes after catheter ablation, and some women carry a higher risk for thromboembolic complications than men. The molecular mechanisms underlying these differences are still poorly understood.

Methods

Gender-based transcriptional patterns were assessed using paired-end, directional RNA sequencing data generated from atrial tissue biopsies in 199 patients either in sinus rhythm or with paroxysmal or persistent AF as part of the CATCH-ME project. Transcript counts were compared between genders separately in the left and right atria using the DESeq2 package in R. The models were adjusted for potential sources of confounding (age, atrial fibrillation status, heart failure status and sequencing batch). Interaction models were implemented using DESeq2 to compare gender*morbidity interactions for persistent AF and HF. Significance was assessed using likelihood ratio tests comparing models with and without the interaction terms. Results with an adjusted P-value  0.05 were considered significant and utilized for subsequent downstream assessments. Differentially expressed (DE) genes were tested for enrichment of gene ontology (GO) terms and KEGG pathways using the WebGestalt toolkit.

Results

Transcriptome-wide profiling across the cohort identified 33 sex-differentiated genes in the left atria and 51 in the right atrial samples, with 21 of these showing bilateral differences. Interestingly, 36 (44%) of the results from these analyses were comprised of non-coding transcripts, including long non-coding RNAs (lncRNAs), antisense RNAs and pseudogenes. GO and pathway enrichment analyses for these genes revealed their involvement in critical pathways such as the complement and coagulation cascades and RNA transport.  Interaction analyses between gender and AF identified two genes (MPP2 & GNAS-AS1) that were differentially transcribed in the right atria and one gene (MYL2) that was DE in the left atria by gender in persistent AF samples. A similar analysis comparing gender*HF morbidity also revealed evidence of DE. Four transcripts (HLA-DQB1-AS1, EIF1AY, UTY and ZFY-AS1) showed gender-specific differences in expression by HF status in left atria, while HLA-DQB1-AS1 was differentially regulated by gender and HF status in right atrial samples.

Conclusions

These RNA-seq analyses provide novel insights into gender-related differences in the transcriptional landscape of right and left adult human atrial appendages. Moreover, interaction analyses identified three genes DE in female atria in persistent AF and four DE genes in female atria in heart failure, providing a molecular anchor for the observed differences in atrial diseases phenotypes between men and women.

Triple therapy in the elderly patients and women – results from the MUNICH triple cohort in patients with AF undergoing PCI

Introduction

Approximately 20% of patients with atrial fibrillation (AF) are suffering from coronary artery disease (CAD), requiring percutaneous coronary intervention (PCI) and stenting over time. These patients are in need of a so-called “triple therapy” (TT) for prevention of stent thrombosis and stroke. Prospective and randomized trials examined risk for bleeding in TT and compared it to a dual regimen, but in majority excluded elderly patients. Moreover, in all to date presented triple therapy trials women represent a minority of included patients (mostly &lt;30%). This raises the question, why female and elderly patients are underrepresented and these groups have a different outcome then younger and male patients, when treated with a guideline recommended TT.

Methods

The objective of our retrospective cohort study was to determine the number of women and elderly patients with the indication for TT and to evaluate the differences in medical treatment. Furthermore, we evaluated safety, represented by bleeding (BARC ≥2 bleedings) and efficacy endpoints (composite clinical endpoint: all-cause-death, myocardial infarction, stent thrombosis, stroke and other systemic thromboembolism) in women vs. men, and elderly vs. younger patients. Moreover, we investigated the influence of NOAC (new oral anticoagulant) vs. VKA (vitamin K antagonist) treatment. Follow-ups were performed via phone-calls or in-hospital visits.

Results

In total, we included 928 patients with AF, that underwent PCI and stenting. Mean follow-up was 464 days. 627 patients were &lt;80 years old (mean age: 72±7 years), 301 were ≥80 years old (mean age: 84±4 years). Only 27.9% of all patients were female. The number of men and women receiving TT was comparable (83.0% vs. 82.2%, p=0.78), while in the younger group significantly more patients received TT (537 (85.6%) vs. 228 (74.7%) (p&lt;0.001). The incidence of BARC ≥2 bleedings in patients with TT was not significantly different in younger vs. older patients and in men vs. women. Also, the incidence of the composite clinical endpoint did not differ significantly in both comparisons.

Conclusion

In our real-life cohort female sex represents around a quarter of TT patients in line with large RCTs. But, unlike the large RCTs, 1/3 of our included patients were older then 80 years and seem to be underrepresented in randomized TT trials.

TT seems to be safe in elderly as well as in female patients. As they both represent an important group, future trials should focus more on including a well balanced patient cohort to improve the applicability of the results.

Funding Acknowledgement

Type of funding source: None

High-density Mapping Guided Pulmonary Vein Isolation for Treatment of Atrial Fibrillation - Two-year clinical outcome of a single center experience

Pulmonary vein isolation (PVI) as interventional treatment for atrial fibrillation (AF) aims to eliminate arrhythmogenic triggers from the PVs. Improved signal detection facilitating a more robust electrical isolation might be associated with a better outcome. This retrospective cohort study compared PVI procedures using a novel high-density mapping system (HDM) with improved signal detection vs. age- and sex-matched PVIs using a conventional 3D mapping system (COM). Endpoints comprised freedom from AF and procedural parameters. In total, 108 patients (mean age 63.9 ± 11.2 years, 56.5% male, 50.9% paroxysmal AF) were included (n = 54 patients/group). Our analysis revealed that HDM was not superior regarding freedom from AF (mean follow-up of 494.7 ± 26.2 days), with one- and two-year AF recurrence rates of 38.9%/46.5% (HDM) and 38.9%/42.2% (COM), respectively. HDM was associated with reduction in fluoroscopy times (18.8 ± 10.6 vs. 29.8 ± 13.4 min; p < 0.01) and total radiation dose (866.0 ± 1003.3 vs. 1731.2 ± 1978.4 cGy; p < 0.01) compared to the COM group. HDM was equivalent but not superior to COM with respect to clinical outcome after PVI and resulted in reduced fluoroscopy time and radiation exposure. These results suggest that HDM-guided PVI is effective and safe for AF ablation. Potential benefits in comparison to conventional mapping systems, e.g. arrhythmia recurrence rates, have to be addressed in randomized trials.

Alteration of Endothelin 1, MCP-1 and Chromogranin A in patients with atrial fibrillation undergoing pulmonary vein isolation

BACKGROUND

The relation between arrhythmias and stress is known. The aim of our current study was to elucidate whether plasma levels of previously described stress parameters are altered in highly symptomatic patients with atrial fibrillation (AF) per se and in patients undergoing ablation therapy by pulmonary vein isolation (PVI).

METHODS

96 patients with AF undergoing PVI were recruited. Plasma levels of Endothelin-1 (ET-1), MCP-1 and Chromogranin-A (CGA) were measured before and three months after ablation completed with clinical follow-up with respect to AF recurrence. Additionally, we examined 40 healthy age- and sex-matched volunteers as a reference.

RESULTS

Symptomatic AF patients showed increased levels of ET-1 compared to healthy controls (2.62pg/ml vs. 1.57pg/ml; p<0.01). Baseline levels of ET-1 were higher in patients presenting with AF after PVI (2.96pg/ml vs. 2.57pg/ml;p = 0.02). The temporal comparison revealed decreased ET-1 levels in patients without (2.57pg/ml vs. 2.33pg/ml; p<0.01) and unchanged ET-1 levels in patients with AF after PVI. Baseline MCP-1 was increased in AF patients vs. controls (268pg/ml vs. 227 pg/ml; p = 0.03). Both groups, with and without AF after PVI, showed an increase of MCP-1 compared to baseline (268pg/ml vs. 349pg/ml;p<0.01; 281pg/ml vs. 355pg/ml;p = 0.03). CGA was lower in AF patients compared to healthy controls (13.8ng/ml vs. 25.6ng/ml;p<0.01). Over time patients without AF after PVI showed an increase of CGA (14.2ng/ml vs. 20.7ng/ml;p<0.01). No change was observed in patients with AF after PVI.

CONCLUSION

Our study demonstrated dysregulated levels of ET-1, MCP-1 and CGA in symptomatic AF patients. We could demonstrate an association between ET-1 to presence or absence of AF. Furthermore, we could show that a decrease of ET-1 as well as an increase of CGA after PVI, representing a trend towards control cohort levels, were both associated with restoration of sinus rhythm. These results provide new insights into the role of stress-related biomarkers in AF and AF treatment by ablation therapy.

Diagnostic and prognostic value of miR-1 and miR-29b on adverse ventricular remodeling after acute myocardial infarction - The SITAGRAMI-miR analysis

BACKGROUND

MicroRNAs (miRs) have shown to exert fibrotic and anti-fibrotic effects in preclinical models of acute myocardial infarction (AMI). The aim of this study was to evaluate miR-1, miR-21, miR-29b and miR-92a as circulating biomarkers for adverse ventricular remodeling (AVR) in post-AMI patients.

METHODS

Plasma levels of miR-1, miR-21, miR-29b and miR-92a were measured in 44 patients of the SITAGRAMI trial population at day 4, day 9 and 6month after AMI and in 18 matched controls (CTL). MiR expression patterns were correlated with magnetic resonance imaging (MRI) parameters for AVR (absolute change (Δ) in infarct volume (IV), left ventricular ejection fraction (LVEF) and left ventricular end-diastolic volume (LVEDV) between day 4 and 6months after AMI) and a combined cardiovascular endpoint.

RESULTS

Expression of miR-1, miR-21 and miR-29b but not miR-92a was increased in AMI vs. CTL cohort showing highest miR levels at d9. However, only miR-1 and miR-29b levels significantly correlated with ΔIV and showed a trend for correlation with ΔLVEF. Only miR-29b levels at day 9 correlated with ΔLVEDV at 6-month follow-up. There was no correlation of miR levels with an adverse outcome.

CONCLUSION

Mir-1 and miR-29b plasma levels post-AMI correlate with IV changes. In addition, miR-29b levels are associated with changes of LVEDV over time. These results provide insights into the role of miRs as diagnostic AVR surrogate markers. Further large scale clinical trials will be needed to evaluate the real prognostic relevance of these miRs with respect to a clinical implication in the future.

Gene expression of brain natriuretic peptide in isolated atrial and ventricular human myocardium: influence of angiotensin II and diastolic fiber length

BACKGROUND

We studied the effects of angiotensin II (Ang II) and diastolic overstretch on the induction of cardiac growth in isometrically contracting muscle preparations from human right atria and left ventricles. We used the gene expression of brain natriuretic peptide (BNP) as a molecular marker of cardiac hypertrophy.

METHODS AND RESULTS

Northern blot analysis was performed in human atrial muscle preparations, which were either incubated in 10(-6) mol/L Ang II for 45 minutes or diastolically stretched to 120% of optimum muscle length. Similar experiments were performed with human left ventricular muscle preparations. Results were as follows: (1) BNP gene expression increased in human atrial myocardium 4-fold when stimulated by Ang II (n=7, P<0.001). (2) Diastolic overstretch increased BNP expression in a time-dependent manner. The linear regression equations for the BNP/GAPDH ratio as a function of time (hours) were y=1.21+0.62x (P:<0.001) for overstretched preparations and y=1.07-0.01x (P:=NS) for atrial preparations kept at physiological muscle length. (3) In left ventricular human muscle preparations, diastolic overstretch and Ang II increased BNP gene expression as well. (4) In addition, the Ang II subtype 1 receptor blocker losartan was able to block the effects of Ang II and diastolic overstretch.

CONCLUSIONS

Cardiac hypertrophy can be induced in isolated human atrial and left ventricular intact myocardium by Ang II and diastolic overstretch but not by isometric afterload. The fact that the induction of cardiac growth is inhibited by the blockade of Ang II subtype 1 receptors is of scientific and clinical importance.