Antibiotic hyper-resistance in a class I aminoacyl-tRNA synthetase with altered active site signature motif

Antibiotics target key biological processes that include protein synthesis. Bacteria respond by developing resistance, which increases rapidly due to antibiotics overuse. Mupirocin, a clinically used natural antibiotic, inhibits isoleucyl-tRNA synthetase (IleRS), an enzyme that links isoleucine to its tRNAIle for protein synthesis. Two IleRSs, mupirocin-sensitive IleRS1 and resistant IleRS2, coexist in bacteria. The latter may also be found in resistant Staphylococcus aureus clinical isolates. Here, we describe the structural basis of mupirocin resistance and unravel a mechanism of hyper-resistance evolved by some IleRS2 proteins. We surprisingly find that an up to 103-fold increase in resistance originates from alteration of the HIGH motif, a signature motif of the class I aminoacyl-tRNA synthetases to which IleRSs belong. The structural analysis demonstrates how an altered HIGH motif could be adopted in IleRS2 but not IleRS1, providing insight into an elegant mechanism for coevolution of the key catalytic motif and associated antibiotic resistance.

POS0108 REMISSION OR NOT REMISSION? THAT’S THE QUESTION, BUT WHAT’S THE ANSWER? - ILLUMINATING ON REMISSION IN ORDINARY OUTPATIENT CLINICAL RHEUMATOID ARTHRITIS PATIENTS

Background

A recent meta-analysis by Ferreira et al. (2020) has questioned the validity of using Patient Global Assessment (PGA) to define remission in the Boolean remission criteria (4-variable remission, 4vR) [1]. This is because PGA, which presumptively reflects a patient’s perception of disease activity, is influenced by both inflammatory and non-inflammatory mechanisms, thus questioning the validity of PGA-related remission definitions when treating patients to target using anti-inflammatory drugs. Further, the impact of PGA differs in the various definitions and algorithms developed to define remission in rheumatoid arthritis (RA).

Objectives

This study aims to examine remission rates by applying different definitions of remission in an outpatient cohort of RA patients and illuminate the impact of PGA on Boolean remission.

Methods

Data were obtained during 2019 from RA patients followed at an outpatient clinic in Southern Norway. The composite disease activity scores simple disease activity index (SDAI), clinical disease activity index (CDAI), and disease activity score with 28 joint count with C-reactive peptide (DAS28(3) and with PGA DAS28(4)), as well as Boolean 4vR and without PGA the 3-variable remission (3vR) were used to define remission. Cut-off remission values for CDAI, SDAI, and DAS28 are ≤2.8, ≤3.2, and ≤2.6, respectively. 4vR is attained when PGA ≤10, C-reactive peptide (CRP) ≤10 mg/L, SJC28 ≤1, and TJC28 ≤1, while 3vR when CRP ≤10 mg/L, TJC28 and SJC28 ≤1 [2]. Remission rates for 4vR were also calculated with the PGA cut-offs of ≤20, 30, 40, 50, 60, 70, 80, 90.

Results

In Figure 1, proportion rates of remission for DAS28(3), DAS28(4), CDAI, SDAI, 3vR, and 4vR with different PGA cut-offs are presented. The proportion of remission were 73% for DAS28(3), 67% for DAS28(4), 37% for CDAI, 38% for SDAI, 23% for 4vR, 65% for 3vR. When comparing the different remissions proportion rate with various cut-offs of PGA in 4vR, SDAI and CDAI lie between a cut-off of ≤20 and ≤30, while DAS28(3), DAS28(4), and 3vR all lies beyond a cut-off of ≤90.

Figure 1.

Remission rates using different definitions of remission in an outpatient cohort of 502 rheumatoid arthritis patients

Conclusion

Our data highlights that there is a great variation in remission rates for the different remission definitions, with DAS28(3) having the highest (73%) and the original Boolean remission the lowest (23%) remission rate. While RA patients in DAS28 remission may still have swollen joints, RA patients with no swollen and tender joints and normal CRP may not achieve Boolean remission because of even a minor elevation of PGA above ten, which may not only reflect inflammatory mechanisms. We question the value of using remission definitions where PGA has a large impact when used in ordinary clinical practice to treat patients to remission. Further studies are warranted to illuminate which remission definitions should be used both in studies and in ordinary clinical practice when treating patients with anti-inflammatory drugs.

Is it time for a paradigm shift to focus more on objective than subjective measures reflecting disease status and disease activity when aiming for remission daily clinical practice?

References

[1]Ferreira RJO, Welsing PMJ, Jacobs JWG, Gossec L, Ndosi M, Machado PM, et al. Revisiting the use of remission criteria for rheumatoid arthritis by excluding patient global assessment: an individual meta-analysis of 5792 patients. Ann Rheum Dis. 2020.

[2]Felson DT, Smolen JS, Wells G, Zhang B, van Tuyl LH, Funovits J, et al. American College of Rheumatology/European League Against Rheumatism provisional definition of remission in rheumatoid arthritis for clinical trials. Arthritis Rheum. 2011;63(3):573-86.

Acknowledgements

To all patients, nurses, and doctors who contributed to the data collection

Disclosure of Interests

None declared

Feasibility and safety of left atrial access for ablation of atrial fibrillation in patients with persistent left superior vena cava

BACKGROUND

In patients with persistent left superior vena cava (PLSVC) ablation procedures can be challenging. We sought to determine the feasibility and safety of left atrial ablations in patients with PLSVC, especially when PLSVC is unknown prior to the ablation procedure.

METHODS AND RESULTS

In this retrospective analysis 15 adult patients (mean age 64.6 ± 14.5 years, 53.3% male) with PLSVC undergoing 27 ablation procedures for atrial fibrillation or left atrial flutter were included. In 5 (33,3%) patients PLSVC was only discovered during the procedure. Transseptal puncture (TSP) was declared "difficult" by the ablating physician in 13 of 27 (48,2%) procedures and was not successfully completed in the first attempt in two patients with known PLSVC. Once TSP was successfully completed, all relevant structures were reached both during mapping and ablation in all procedures independent of whether PLSVC was known prior to the procedure. One major complication (3,7%) occurred in 27 procedures in a patient with known PLSVC. In the patients with unknown PLSVC no complication occurred.

CONCLUSION

In experienced hands, left atrial access and ablation in patients with PLSVC is feasible and safe, particularly with regard to patients in whom the PLSVC is unknown prior to the ablation procedure. This article is protected by copyright. All rights reserved.

OP0238 DRUG COST FOR BIOLOGIC AND TARGETED SYNTHETIC DMARDS FOR RHEUMATOID ARTHRITIS PATIENTS IN NORWAY FROM 2010 TO 2019 - A COUNTRY WITH A NATIONAL TENDER SYSTEM FOR DRUG PRESCRIPTION

Background:

Biologic and Target Synthetic disease-modifying antirheumatic drugs (BTSs) have caused a paradigm shift in the treatment of patients with inflammatory joint disorders, e.g., rheumatoid arthritis (RA), where remission is now attainable [1]. The high cost of BTSs has caused restrictions on use and prescription, contributing to inequality of care worldwide [2]. An annual tender system was introduced in 2008 in Norway to reduce the costs of these drugs [3].

Objectives:

Explore changes in drug costs for BTSs for RA patients treated at Norwegian rheumatology outpatient clinics between 2010 and 2019.

Methods:

The project BioRheuma (BIOlogic treatment of patients suffering from inflammatory RHEUMAtic disorders in Norway) aimed to monitor patients treated with BTSs while using a designed computer program. Anonymized data files from the ten participating centers were merged and analyzed (EXCEL and SPSS). For each year in the ten-year period, the annual total cost for BTSs and mean BTS cost for treatment of one patient was calculated for all current BTSs users, for all those who started BTSs, and for patients starting naïve to BTSs. The cost was calculated based on price offers given at the annual tender process for the different years.

Results:

The number of registered RA patients in the databases increased from 4909 in 2010 to 9335 in 2019. Simultaneously, the number of patients treated with BTSs increased from 1959 (39.9%) in 2010 to 4209 (45.1%) in 2019. The total treatment expenditure of these BTS treated patients was lowest in 2010 with 226 million Norwegian Kroner (NOK), highest in 2014 (350 million NOK) treating 3448 patients, and second-lowest in 2019 (255 million NOK).

The number of BTSs used for each year (Figure 1) is shown for all current users, all who started new BTSs treatment, and those starting BTSs naïve to BTSs. The same figure also reports the average cost of treating one RA patient with BTSs in these three groups. For the current users of BTSs, when the number of treated patients during follow-up doubled, the mean cost to treat one patient with BTSs was reduced by approximately 50% (decreasing from 115497 NOK in 2010 to 60701 NOK in 2019). The number of patients starting on BTSs approximately doubled, while keeping a steady small increase for the naïve patients to BTSs (382 in 2010 to 405 in 2019). The average starting treatment cost decreased from 114549 NOK in 2010 to 37384 NOK in 2019, and from 114987 NOK in 2010 to 28249 NOK in 2019, for patients starting on BTSs and for patients naïve to BTSs, respectively.

Figure 1.

A ten-year overview of treating RA patient with BTSs

Conclusion:

Our data shows that the average annual costs of treating a Norwegian RA patient on a current BTS, with a national tender system, were reduced by approximately 50% over the ten years 2010-19. For patients starting on a BTS, the average annual cost was reduced by approximately 75%. The consequence for the payers is that treatment can be offered at a lower price, and thus costly drugs may become more available for patients. We believe that mechanisms like the Norwegian tender system enforced upon the commercial pharmaceutical market improve competition and increase availability and use of costly drugs.

References:

[1]Smolen JS, et al. EULAR recommendations for the management of rheumatoid arthritis with synthetic and biological disease-modifying antirheumatic drugs: 2019 update. Ann Rheum Dis 2020;79;685-99.

[2]Bergstra SA, et al. Inequity in access to bDMARD care and how it influences disease outcomes across countries worldwide: results from the METEOR-registry. Ann Rheum Dis 2018;77:1413–20.

[3]Norwegian Hospital Procurement. (Jan 2021). Available from: https://sykehusinnkjop.no.

Acknowledgements:

To all members of the BioRheuma project

Disclosure of Interests:

None declared

RF electrode-tissue coverage significantly influences steam pop incidence and lesion size

BACKGROUND

Steam pops are a rare complication associated with radiofrequency (RF) ablation and are hard to predict. The aim of this study was to assess the influence of coverage between the RF ablation electrode and cardiac tissue on steam pop incidence and lesion size.

METHODS AND RESULTS

An ex vivo model using porcine cardiac preparations and contact force sensing catheters was designed to perform RF ablations at different coverage levels between the RF electrode and cardiac tissue. During coverage level I, only the distal part of the ablation electrode was in contact with tissue. During coverage level II half of the ablation electrode, and during coverage level III the entire ablation electrode was embedded in tissue. RF applications (n = 60) at different coverage levels I-III were systematically performed using the same standardized ablation protocol. Ablations during coverage level III resulted in a significantly higher rate of steam pops (100%) when compared to ablations during coverage level II (10%) and coverage level I (0%), log rank p < .001. Coverage level I ablations resulted in significantly smaller lesion depths, diameters, and impedance drops when compared to higher coverage level ablations, p < .001. In the controlled ex vivo model, there was no difference in applied contact force or energy between different coverage levels.

CONCLUSIONS

The level of coverage between RF electrode, cardiac tissue, and the surrounding fluid significantly influenced the incidence of steam pops in an ex vivo setup. Larger coverage between RF electrode and tissue resulted in significantly larger lesion dimensions.

Cardiac resynchronisation therapy in patients with left bundle branch block with residual conduction

Aim

To evaluate whether left bundle branch block with residual conduction (rLBBB) is associated with worse outcomes after cardiac resynchronisation therapy (CRT).

Methods

All consecutive CRT implants at our institution between 2006 and 2013 were identified from our local device registry. Pre- and post-implant patient specific data were extracted from clinical records.

Results

A total of 690 CRT implants were identified during the study period. Prior to CRT, 52.2% of patients had true left bundle branch block (LBBB), 19.1% a pacing-induced LBBB (pLBBB), 11.2% a rLBBB, 0.8% a right bundle branch block (RBBB), and 16.5% had a nonspecific intraventricular conduction delay (IVCD) electrocardiogram pattern. Mean age at implant was 67.5 years (standard deviation [SD] = 10.6), mean left ventricular ejection fraction (LV EF) was 25.7% (SD = 7.9%), and mean QRS duration was 158.4 ms (SD = 32 ms). After CRT, QRS duration was significantly reduced in the LBBB (p < 0.001), pLBBB (p < 0.001), rLBBB (p < 0.001), RBBB (p = 0.04), and IVCD groups (p = 0.03). LV EF significantly improved in the LBBB (p < 0.001), rLBBB (p = 0.002), and pLBBB (p < 0.001) groups, but the RBBB and IVCD groups showed no improvement. There was no significant difference in mortality between the LBBB and rLBBB groups. LV EF post-CRT, chronic kidney disease, hyperkalaemia, hypernatremia, and age at implant were significant predictors of mortality.

Conclusion

CRT in patients with rLBBB results in improved LV EF and similar mortality rates to CRT patients with complete LBBB. Predictors of mortality post-CRT include post-CRT LV EF, presence of CKD, hyperkalaemia, hypernatremia, and older age at implant.

Early recurrence after pulmonary vein isolation is associated with inferior long-term outcomes: Insights from a retrospective cohort study

AIMS

The aim of this retrospective cohort study was to assess the influence of early recurrence (ER) after pulmonary vein isolation (PVI) for paroxysmal atrial fibrillation (AF) on long-term outcomes and to identify clinical variables associated with ER.

METHODS

We retrospectively collected clinical and procedural data from 1285 patients with paroxysmal AF who underwent PVI from 2011 to 2016. Kaplan-Meier, receiver operating characteristic (ROC) curve, logistic and Cox regression analyses were performed to analyze the influence of ER on long-term outcomes.

RESULTS

ER was observed in 13% of patients. Kaplan-Meier analyses showed significantly different outcomes in 1285 patients with and without ER (49% vs 74%, log rank P < .01) and in 286 patients in the subgroup that underwent reablation (44% vs 79%, log rank P < .01). The hazard ratio (HR) of ER was 1.7 within 48 hours (5% of patients), 2.7 within 1 month (5%), 3.0 within 2 months (2%), and 6.4 within 3 months (1%) for late recurrence (LR), P < .01. ROC analysis (area under the curve [AUC] = 0.79) resulted in 70.3% sensitivity and 74.2% specificity for a 14-day blanking period, and 53.1% sensitivity and 85.5% specificity for a 30-day blanking period. Female patients (odds ratio [OR] 1.69, P < .01) and those with diabetes (OR 1.95, P = .01) were at higher risk for ER.

CONCLUSIONS

ER is observed in a substantial number of patients with paroxysmal AF after PVI and has a continuous direct effect on LR according to the timing of ER. Randomized trials are required to assess the safety and effects of reablations in a shortened blanking period on long-term outcomes.

Safety and outcome of very high-power short-duration ablation using 70 W for pulmonary vein isolation in patients with paroxysmal atrial fibrillation

Aims

Pulmonary vein isolation (PVI) using radiofrequency ablation (RFA) in patients with paroxysmal atrial fibrillation (PAF) is effective but hampered by pulmonary vein reconnection due to insufficient ablation lesions. High-power delivery over a short period of time (HPSD) in RFA is stated to create more efficient lesions. The aim of this study was to compare intraprocedural safety and outcome of HPSD ablation to conventional power settings in patients undergoing PVI for PAF.

Methods and results

We included 197 patients with PAF that were scheduled for PVI. An ablation protocol with 70 W and a duration cut-off of 7 s at the anterior left atrium (LA) and 5 s at the posterior LA (HPSD group; n = 97) was compared to a conventional power protocol with 30–40 W for 20–40 s (standard group; n = 100) in terms of periprocedural complications and a 1-year outcome. The HPSD group showed significantly less arrhythmia recurrence during 1-year follow-up with 83.1% of patients free from atrial fibrillation compared to 65.1% in the standard group (P &lt; 0.013). No pericardial tamponade, periprocedural thromboembolic complications, or atrio-oesophageal fistula occurred in either group. Mean radiofrequency time (12.4 ± 3.4 min vs. 35.6 ± 12.1 min) and procedural time (89.5 ± 23.9 min vs. 111.15 ± 27.9 min) were significantly shorter in the HPSD group compared to the standard group (both P &lt; 0.001).

Conclusion

High-power short-duration ablation demonstrated a comparable safety profile to conventional ablation. High-power short-duration ablation using 70 W for 5–7 s leads to significantly less arrhythmia recurrences after 1 year. Radiofrequency and procedural time were significantly shortened.

Patients with pacemakers or defibrillators do not need to worry about e-Cars: An observational study

BACKGROUND

Electric cars are increasingly used for public and private transportation and represent possible sources of electromagnetic interference (EMI). Potential implications for patients with cardiac implantable electronic devices (CIED) range from unnecessary driving restrictions to life-threatening device malfunction. This prospective, cross-sectional study was designed to assess the EMI risk of electric cars on CIED function.

METHODS

One hundred and eight consecutive patients with CIEDs presenting for routine follow-up between May 2014 and January 2015 were enrolled in the study. The participants were exposed to electromagnetic fields generated by the four most common electric cars (Nissan Leaf, Tesla Model S, BMW i3, VW eUp) while roller-bench test-driving at Institute of Automotive Technology, Department of Mechanical Engineering, Technical University, Munich. The primary endpoint was any abnormalities in CIED function (e.g. oversensing with pacing-inhibition, inappropriate therapy or mode-switching) while driving or charging electric cars as assessed by electrocardiographic recordings and device interrogation.

RESULTS

No change in device function or programming was seen in this cohort which is representative of contemporary CIED devices. The largest electromagnetic field detected was along the charging cable during high current charging (116.5 μT). The field strength in the cabin was lower (2.1-3.6 μT).

CONCLUSIONS

Electric cars produce electromagnetic fields; however, they did not affect CIED function or programming in our cohort. Driving and charging of electric cars is likely safe for patients with CIEDs.

Heparanase link between vasculogenesis and angiogenesis as well as a predictive factor of a shorter survival rate

Heparanase concentration is low in normal epithelia cells but its overexpression is reported in many carcinomas, including sarcomas and haematological malignancies. The purpose of this study was to investigate the association with selected angiogenic parameters as well as in the number of circulating endothelial progenitors (EPCs) in respect to low, moderate and high concentrations of heparanase. Also, we estimated the diagnostic usefulness of the heparanase concentration for disease recurrence prediction in breast cancer cases. Eighty-six patients with IA-IIB stage invasive breast carcinoma who passed a comprehensive clinicopathologic evaluation were included in the study. The median tumour diameter was 1.5 cm. Twenty cases showed lymph node metastasis (N1). Follow-up was completed in all patients a median follow-up was 33.5 months with a 11.6% recurrence rate. An immunoassay of selected angiogenic parameters, heparanase, as well as an immunohistochemistry of oestrogen and progesterone receptors, human epidermal growth factor receptor 2 (HER2), Ki67 and E-cadherin was performed in all cases. Circulating EPCs were determined by flow cytometry. Higher levels of heparanase in oestrogen and progesterone receptor negative cancers than in positive ones were noted. A higher concentration of heparanase was observed in T2 cases than T1 subjects. Significant positive associations between circulating EPCs, soluble forms of VEGF receptors and increasing plasma levels of heparanase were obtained. Follow-up revealed a significantly higher incidence of disease relapse in breast cancer patients with high baseline concentrations of heparanase. Heparanase was the most accurate biomarker with an AUC^ROC = 0.72. The cut-off value of 213.74 pg/mL was identified in order to discriminate between disease recurrence patients and those without disease relapse. We suggest, that a high concentration of heparanase next to tumour size and oestrogen and progesterone receptor expression may serve as an indicator of a more an aggressive character of tumour cells and a shorter survival rate.

Safety of Uninterrupted Periprocedural Edoxaban Versus Phenprocoumon for Patients Who Underwent Left Atrial Catheter Ablation Procedures

Data about the safety of edoxaban in patients who underwent left atrial (LA) radiofrequency (RF) ablation procedures are lacking. This study sought to compare the safety of uninterrupted edoxaban with uninterrupted phenprocoumon administration during LA RF ablation for atrial fibrillation and atrial tachycardia. In total, 231 patients (mean age 64 ± 11years, male 71%) who underwent LA RF ablation under continuous oral anticoagulation (OAC) with edoxaban or phenprocoumon were included in the study. Patients on uninterrupted edoxaban (60 mg or 30 mg/day for at least 4 weeks) were matched for gender, age and type of arrhythmia with 2 patients on uninterrupted phenprocoumon (international normalized ratio 2 to 3). We identified 77 consecutive patients on edoxaban and n = 154 patients on phenprocoumon. Heparin was administered periprocedurally to achieve an activated clotting time of 280 to 300 seconds. No protamine was administered periprocedurally. The primary end point was a composite of bleeding, thromboembolic events, and death. The primary end point was met in 9 patients in the edoxaban group and in 22 patients in the phenprocoumon group (p = 0.69). No patient in either group died or had a thromboembolic complication. No major bleeding complication was observed in the edoxaban group, whereas one was found in 1 patient in the phenprocoumon group (p ≥0.99). Minor bleeding complications occurred in 9 patients (12%) in the edoxaban group and in 21 patients (14%) in the phenprocoumon group (p = 0.84). Uninterrupted OAC with edoxaban appeared to be as safe as uninterrupted OAC with phenprocoumon in patients who underwent LA RF ablation procedures.

Increased number of endothelial progenitors in peripheral blood as a possible early marker of tumour growth in post-menopausal breast cancer patients

The aim of the study was to evaluate the number of circulating endothelial progenitor cells (circulating EPCs) in the blood of patients diagnosed with breast cancer and to make an attempt at finding associations with the number of circulating EPCs and selected clinic-pathological factors; TNM and histological grading, molecular subtype of breast cancer, hormonal status, the expression of Ki-67 and the size of tumour. The study involved 96 Caucasian ethnicity post-menopausal women. Sixty-six women aged 48 - 63 (mean age 55) with breast cancer diagnosis without distant metastases (M0). The median value of the tumour diameter was 1.51 cm. The control group consisted of 30 healthy, non-smoking, post-menopausal women, mean age 49, range 44 - 54 years of age. The exclusion criteria for all the participants were hypertension, hyperlipidaemia, and hyperglycaemia, acute and chronic infection. With regard to the fresh blood samples the number of circulating endothelial progenitors was determined using flow cytometry. The fluorescence of 100,000 cells was measured during the analysis. Circulating EPCs were identified with the immune-phenotype CD45^-, CD34⁺, CD133⁺, CD31⁺. A significantly higher number of circulating EPCs in the study group, as compared to the controls (P = 0.0001) and a significantly higher number of circulating EPCs in women over 60 with breast cancer than in the younger women (P = 0.0029) were reported. A positive correlation was noted between circulating EPCs and age as well as between circulating EPCs and HER-2 (P = 0.0231, P = 0.0414, respectively), and a negative correlation between circulating EPCs and histological grading of breast cancer (P = 0.0272). The study has shown a higher number of circulating EPCs in breast cancer patients, which indicates stimulation of neovascularization. Additionally, since bone morrow-derived circulating EPCs are more intensively mobilised in older and overweight breast cancer patients, we can speculate that more aggressive neo-angiogenesis can occur in those patients.

Right Bundle Branch Block-Like Pattern During Uncomplicated Right Ventricular Pacing and the Effect of Pacing Site

Right bundle branch block (RBBB) configuration is an unexpected finding during right ventricular (RV) pacing that raises the suspicion of inadvertent left ventricular lead positioning. The aim of this study was to evaluate the prevalence of paced RBBB pattern in relation to RV lead location. This is a secondary analysis of a prospective, multicenter study, which randomized implantable cardioverter defibrillator recipients to an apical versus midseptal defibrillator lead positioning. A 12-lead electrocardiogram was recorded during intrinsic rhythm and RV pacing. Paced RBBB-like pattern was defined as positive (>0.05 mV) net amplitude of QRS complex in leads V1 and/or V2. In total, 226 patients (65.6 ± 12.0 years, 20.8% women, 53.1% apical site) were included in the study. The prevalence of paced RBBB pattern in the total population was 15.5%. A significantly lower percentage of patients in the midseptal group demonstrated RBBB-type configuration during RV pacing compared with the apical group (1.9% vs 27.5%, p <0.001). Baseline RBBB, prolonged QRS duration during intrinsic rhythm, and reduced ejection fraction were not associated with increased likelihood of paced RBBB. In the subgroup of patients with RBBB type during pacing, 91.4% of patients had a paced QRS axis from -30° to -90°, whereas 100% of patients displayed a negative QRS vector at lead V3. In conclusion, RBBB configuration is encountered in a considerable percentage of device recipients during uncomplicated RV pacing. Midseptal lead positioning is associated with significantly lower likelihood of paced RBBB pattern compared with apical location.

Evaluation of a new very low dose imaging protocol: feasibility and impact on X-ray dose levels in electrophysiology procedures

Aims

This study presents and evaluates the impact of a new lowest-dose fluoroscopy protocol (Siemens AG), especially designed for electrophysiology (EP) procedures, on X-ray dose levels.

Methods and results

From October 2014 to March 2015, 140 patients underwent an EP study on an Artis zee angiography system. The standard low-dose protocol was operated at 23 nGy (fluoroscopy) and at 120 nGy (cine-loop), the new lowest-dose protocol was operated at 8 nGy (fluoroscopy) and at 36 nGy (cine-loop). Procedural data, X-ray times, and doses were analysed in 100 complex left atrial and in 40 standard EP procedures. The resulting dose–area products were 877.9 ± 624.7 µGym² (n = 50 complex procedures, standard low dose), 199 ± 159.6 µGym² (n = 50 complex procedures, lowest dose), 387.7 ± 36.0 µGym² (n = 20 standard procedures, standard low dose), and 90.7 ± 62.3 µGym² (n = 20 standard procedures, lowest dose), P < 0.01. In the low-dose and lowest-dose groups, procedure times were 132.6 ± 35.7 vs. 126.7 ± 34.7 min (P = 0.40, complex procedures) and 72.3 ± 20.9 vs. 85.2 ± 44.1 min (P = 0.24, standard procedures), radiofrequency (RF) times were 53.8 ± 26.1 vs. 50.4 ± 29.4 min (P = 0.54, complex procedures) and 10.1 ± 9.9 vs. 12.2 ± 14.7 min (P = 0.60, standard procedures). One complication occurred in the standard low-dose and lowest-dose groups (P = 1.0).

Conclusion

The new lowest-dose imaging protocol reduces X-ray dose levels by 77% compared with the currently available standard low-dose protocol. From an operator standpoint, lowest X-ray dose levels create a different, reduced image quality. The new image quality did not significantly affect procedure or RF times and did not result in higher complication rates. Regarding radiological protection, operating at lowest-dose settings should become standard in EP procedures.

C1-INH and its Effect on Infarct Size and Ventricular Function in an Acute Pig Model of Infarction, Cardiopulmonary Bypass, and Reperfusion

BACKGROUND

Recent studies suggest that complement inhibition reduces reperfusion injury. A clinical setting with local application of a C1 esterase inhibitor (C1-INH) has been modeled in an animal study in order to further investigate these findings.

METHODS

In 21 pigs, the left anterior descending coronary artery (LAD) was occluded distally to the first diagonal branch for 2 hours (h), including 1 h of cardioplegic arrest during CPB. After release of the coronary snare, C1-INH or NaCl (control) was applied to the aortic root. Thereafter, the aortic cross-clamp was removed and the heart was reperfused for 30 minutes before weaning from CPB. Left ventricular pressure volume analysis was performed by a multielectrode conductance catheter and the area at risk and infarct size were determined from excised hearts.

RESULTS

The following data were observed (mean+/-SEM) for the control group and the C1-INH group, respectively, after 1-h ligation of the LAD: heart rate (HR) 86+/-3 and 93+/-6 beats/min, stroke volume (SV) 1.2+/-0.1 and 1.2+/-0.1 ml/kg, aortic pressure (AoP) 83+/-6 and 87+/-5 mmHg, left ventricular end-diastolic pressure (LVedP) 12+/-1 and 11+/-2 mmHg; two hours after weaning from CPB: HR 106+/-9 and 123+/-4 beats/min, SV 0.9+/-0.1 and 0.9+/-0.1 ml/kg, AoP 65+/-5 and 79+/-7 mmHg, LVedP 9+/-1 and 8+/-1 mmHg. Conductance catheter measurements showed no improved left ventricular performance after C1-INH application. Infarct size to area at risk ratio was 61.5+/-4.2% for controls and 61.4+/-4.8% for C1-INH.

CONCLUSIONS

Intracoronary application of complement inhibitor in an acute infarction model, which mimicked a clinical setting of urgent coronary bypass grafting after ischemia, has been shown to neither influence the area of infarction, nor the ventricular function.