Rationale and design of the iCORONARY trial: improving the cost-effectiveness of coronary artery disease diagnosis

BACKGROUND

In patients with stable coronary artery disease (CAD), revascularisation decisions are based mainly on the visual grading of the severity of coronary stenosis on invasive coronary angiography (ICA). However, invasive fractional flow reserve (FFR) is the current standard to determine the haemodynamic significance of coronary stenosis. Non-invasive and less-invasive imaging techniques such as computed-tomography-derived FFR (FFR-CT) and angiography-derived FFR (QFR) combine both anatomical and functional information in complex algorithms to calculate FFR.

TRIAL DESIGN

The iCORONARY trial is a prospective, multicentre, non-inferiority randomised controlled trial (RCT) with a blinded endpoint evaluation. It investigates the costs, effects and outcomes of different diagnostic strategies to evaluate the presence of CAD and the need for revascularisation in patients with stable angina pectoris who undergo coronary computed tomography angiography. Those with a Coronary Artery Disease-Reporting and Data System (CAD-RADS) score between 0-2 and 5 will be included in a prospective registry, whereas patients with CAD-RADS 3 or 4A will be enrolled in the RCT. The RCT consists of three randomised groups: (1) FFR-CT-guided strategy, (2) QFR-guided strategy or (3) standard of care including ICA and invasive pressure measurements for all intermediate stenoses. The primary endpoint will be the occurrence of major adverse cardiac events (death, myocardial infarction and repeat revascularisation) at 1 year.

CLINICALTRIALS

gov-identifier: NCT04939207.

CONCLUSION

The iCORONARY trial will assess whether a strategy of FFR-CT or QFR is non-inferior to invasive angiography to guide the need for revascularisation in patients with stable CAD. Non-inferiority to the standard of care implies that these techniques are attractive, less-invasive alternatives to current diagnostic pathways.

Stent length and -diameter and long-term clinical outcomes following percutaneous coronary intervention with drug-eluting stent implantation

Background

Long total stent length and small stent diameter have been associated with adverse events following percutaneous coronary intervention (PCI).

Purpose

To assess whether stent length and -diameter influence long-term target-lesion failure (TLF) following implantation of contemporary drug-eluting stents (DES) in an all-comers population undergoing PCI.

Methods

Patients included in the ReCre8 trial were stratified for troponin status and diabetes and randomized to implantation of a permanent polymer (PP-ZES) or polymer-free stent (PF-AES). Troponin negative patients were treated with dual antiplatelet therapy for one month, and troponin positive patients for twelve months. For the analysis on stent length, patients were divided in the quartiles of total stent length implanted per patient. Group 1a had a stent length of ≤18mm, Group 2a had a total stent length between 18 and 30mm, Group 3a had a total stent length of ≥30mm and lower than 49mm, and Group 4a had a total stent length of 49mm or more. For the analysis on stent diameter, patients were divided in the quartiles of the smallest stent diameter implanted per patient. Group 1b had a minimal stent diameter of ≤2.5mm, Group 2b had a minimal stent diameter between 2.5 and 3mm, Group 3b had a minimal stent diameter of ≥3mm and lower than 3.5mm, and Group 4b had a minimal stent diameter of 3.5mm or higher. The primary endpoint of TLF and its components – cardiac death, target-vessel myocardial infarction and target-lesion revascularization (TLR) – were assessed after three years.

Results

After division of patients in subgroups based on stent length, Group 1a included 409 patients (27.6%), Group 2a included 322 patients (20.7%), Group 3a included 376 patients (25.3%) and Group 4a included 377 patients (25.4%). After three years, TLF occurred more frequently in Group 4a with 6.6% in Group 1a, 8.4% in Group 2a, 7.7% in Group 3a and 18.0% in Group 4a (p<0.001) as shown in Figure 1. This was driven by a higher rate of TLR (p<0.001) and target-vessel myocardial infarction (p<0.001) in Group 4a. After division of patients in subgroups based on stent diameter, Group 1b included 408 patients (27.5%), Group 2b included 214 patients (14.4%), Group 3b included 477 patients (32.1%) and Group 4b included 386 patients (26.0%). After three years, TLF occurred more frequently in Group 1b with 14.0% vs. 7.9% in Group 2b, 8.6% in Group 3b and 9.3% in Group 4b (p=0.0241) as shown in Figure 2. The difference in TLF was driven by a higher rate of TLR in Group 1b (8.6% vs. 3.7% vs. 4.4% vs. 4.9%; p=0.016).

Conclusion

In an all-comers population undergoing PCI with implantation of contemporary DES, a stent length ≥49mm and a stent diameter ≤2.5mm were associated with a higher rate of TLF after three years.

Funding Acknowledgement

Type of funding sources: None.

Revascularization of significant coronary artery disease in patients undergoing transcatheter aortic valve implantation: a systematic review and meta-analysis

Background

The prevalence of coronary artery disease (CAD) in patients with severe aortic valve stenosis undergoing transcatheter aortic valve implantation (TAVI) is high. However, the importance of a percutaneous coronary intervention (PCI) prior to TAVI has been matter of debate. Importantly, patients undergoing TAVI are characterized by high age often accompanied by highly calcified coronary arteries, increasing the risk of severe periprocedural complications. Moreover, patients with a severe aortic valve stenosis are limited in their ability to compensate for these life-threatening complications. Together with the necessity of dual antiplatelet therapy after PCI, this may explain a possible negative effect of PCI in this patient population. However, there is still insufficient evidence regarding the importance of PCI in patients undergoing TAVI.

Purpose

The aim of this systematic review and meta-analysis was to assess the need for PCI in patients with significant CAD undergoing TAVI.

Methods

A systematic search was conducted to identify studies comparing optimal medical treatment only versus PCI in patients with significant CAD undergoing TAVI. Endpoints were all-cause mortality, cardiac death, stroke, myocardial infarction, and major bleeding which were assessed at 30 days, one year, and beyond one year following TAVI.

Results

A total of 14 studies was included in this meta-analysis, including 3838 patients of which 1806 patients (47.1%) underwent PCI before TAVI. All-cause mortality was not significantly different between optimal medical treatment only and PCI at 30 days (OR: 1.27; 95% CI, 0.91–1.77; p=0.17; I2=0%), at one year (OR: 0.91; 95% CI, 0.64–1.29; p=0.59; I2=45%), and beyond one year (OR 0.68; 95% CI, 0.42–1.08; p=0.10; I2=49%). Cardiac death and myocardial infarction was similar across the groups at 30 days (OR cardiac death: 1.94; 95% CI, 0.36–10.56; p=0.45; I2=28%; OR myocardial infarction: 0.50; 95% CI, 0.13–1.91; p=0.31; I2=0%), and at one year (OR cardiac death: 0.77; 95% CI, 0.19–3.13; p=0.72; I2=84%; OR myocardial infarction: 0.74; 95% CI, 0.21–2.66; p=0.64; I2=18%). Stroke did not significantly differ between PCI and optimal medical treatment groups at 30 days (OR: 0.77; 95% CI, 0.31–1.92; p=0.57; I2=0%). However, patients that underwent TAVI without preceding PCI had significantly lower risk of major bleeding at 30 days (OR: 0.66; 95% CI, 0.46–0.94; p=0.022; I2=0%).

Conclusion

This systematic review and meta-analysis showed no significant differences in clinical outcomes between patients with and without PCI prior to TAVI at both short- and long-term follow-up, apart from a higher risk of major bleeding within 30 days in patients undergoing PCI before TAVI.

Funding Acknowledgement

Type of funding sources: None.

A novel method to identify an intramural segment in interarterial anomalous coronary arteries on CT-angiography

Background/Introduction

An anomalous coronary artery originating from the opposite sinus of Valsalva (ACAOS) with an interarterial course can be assessed using Computed Tomography Angiography (CTA) for the presence of high-risk characteristics associated with sudden cardiac death. These features include a slit-like ostium, acute angle take-off, and degree of proximal luminal narrowing. However, no robust CTA criteria currently exist to determine the presence of an intramural segment.

Purpose

The aim of this study is to deduct a method to accurately identify an intramural course of interarterial ACAOS on CTA imaging.

Methods

All consecutive adult patients with an interarterial ACAOS that were evaluated at the two academic hospitals between January 2010 and July 2019 were screened for inclusion. Inclusion criteria were availability of a preoperative CTA-scan (0.5–1mm slice-thickness) and peroperative confirmation of the intramural segment. Using multiplanar reconstruction of the CTA, the distance between the lumen of the aorta and the lumen of the ACAOS (defined as “interluminal space” (ILS)) was assessed at 2mm intervals along the intramural segment (Figure 1).

Results

Twenty-five patients (64% female, mean age 46 years, 88% right ACAOS) were included. Analysis showed a mean ILS of 0.69mm±0.15mm at 2mm from the ostium. At the end of the intramural segment where the ACAOS becomes non-intramural, the mean ILS was significantly larger (1.27±0.29mm, p<0.001) (Figure 2). Interobserver agreement evaluation showed good reproducibility of ILS (intraclass correlation coefficient 0.77, p<0.001). ROC-analysis demonstrated that at a cut-off ILS of ≤0.95mm, an intramural segment can be diagnosed with 100% sensitivity and 84% specificity.

Conclusion(s)

The ILS is introduced as novel and robust CTA parameter to identify an intramural course of interarterial ACAOS. An ILS of ≤0.95mm is indicative of an intramural segment with 100% sensitivity and 84% specificity.

Funding Acknowledgement

Type of funding sources: None.

A combination of fecal calprotectin and human beta-defensin 2 facilitates diagnosis and monitoring of inflammatory bowel disease

Inflammatory bowel disease (IBD) and irritable bowel syndrome (IBS) show a large overlap in clinical presentation, which presents diagnostic challenges. As a consequence, invasive and burdensome endoscopies are often used to distinguish between IBD and IBS. Here, we aimed to develop a noninvasive fecal test that can distinguish between IBD and IBS and reduce the number of endoscopies.We used shotgun metagenomic sequencing to analyze the composition and function of gut microbiota of 169 IBS patients, 447 IBD patients and 1044 population controls and measured fecal Calprotectin (FCal), human beta defensin 2 (HBD2), and chromogranin A (CgA) in these samples. These measurements were used to construct training sets (75% of data) for logistic regression and machine learning models to differentiate IBS from IBD and inactive from active IBD. The results were replicated on test sets (remaining 25% of the data) and microbiome data obtained using 16S sequencing.Fecal HBD2 showed high sensitivity and specificity for differentiating between IBD and IBS (sensitivity = 0.89, specificity = 0.76), while the inclusion of microbiome data with biomarkers (HBD2 and FCal) showed a potential for improvement in predictive power (optimal sensitivity = 0.87, specificity = 0.93). Shotgun sequencing-based models produced comparable results using 16S-sequencing data. HBD2 and FCal were found to have predictive power for IBD disease activity (AUC ≈ 0.7).HBD2 is a novel biomarker for IBD in patients with gastro-intestinal complaints, especially when used in combination with FCal and potentially in combination with gut microbiome data.

The impact and challenges of implementing CTCA according to the 2019 ESC guidelines on chronic coronary syndromes: a survey and projection of CTCA services in the Netherlands

Background

The 2019 ESC-guidelines on chronic coronary syndromes (ESC-CCS) recommend computed tomographic coronary angiography (CTCA) or non-invasive functional imaging instead of exercise ECG as initial test to diagnose obstructive coronary artery disease. Since impact and challenges of these guidelines are unknown, we studied the current utilisation of CTCA-services, status of CTCA-protocols and modeled the expected impact of these guidelines in the Netherlands.

Methods and results

A survey on current practice and CTCA utilisation was disseminated to every Dutch hospital organisation providing outpatient cardiology care and modeled the required CTCA capacity for implementation of the ESC guideline, based on these national figures and expert consensus. Survey response rate was 100% (68/68 hospital organisations). In 2019, 63 hospital organisations provided CTCA-services (93%), CTCA was performed on 99 CTCA-capable CT-scanners, and 37,283 CTCA-examinations were performed. Between the hospital organisations, we found substantial variation considering CTCA indications, CTCA equipment and acquisition and reporting standards. To fully implement the new ESC guideline, our model suggests that 70,000 additional CTCA-examinations would have to be performed in the Netherlands.

Conclusions

Despite high national CTCA-services coverage in the Netherlands, a substantial increase in CTCA capacity is expected to be able to implement the 2019 ESC-CCS recommendations on the use of CTCA. Furthermore, the results of this survey highlight the importance to address variations in image acquisition and to standardise the interpretation and reporting of CTCA, as well as to establish interdisciplinary collaboration and organisational alignment.

Case report: Dobutamine stress intracoronary physiology and imaging to examine the functional and dynamic properties of an apparent malignant intra-arterial right coronary artery

Background

We present a case concerning a 64-year-old female with complaints of palpitations, chest pain, and an anomalous right coronary artery (RCA) from the opposite sinus (R-ACAOS) with a suspected malignant trajectory on computed tomography. She was referred to our clinic for a second opinion to re-assess the suggested treatment of coronary surgery.

Case summary

A coronary angiogram was performed demonstrating a RCA with a tapered ostium typical for an inter-arterial course. Dobutamine and adenosine stress test during simultaneous intracoronary flow, pressure, and ultrasound assessment, was performed to determine the functional significance. After 120 mcg adenosine, intracoronary baseline flow velocity increased from 14 cm/s to a peak flow velocity of 37 cm/s, demonstrating a sufficient coronary flow velocity reserve (CFVR) of 2.6. No intracoronary pressure drop during maximal hyperaemia was found. After maximum dobutamine stress, CFVR was measured 2.5. Fractional flow reserve measured 0.99. Cross-sectional area measurement through intravascular ultrasound demonstrated a diameter reduction from 14.6 mm² to 8.5 mm². Therefore, we concluded this aberrant trajectory was not of any functional relevance and should be considered non-malignant.

Discussion

There are several anatomic coronary anomalies which may contribute to coronary compression during exercise and are therefore correlated with sudden cardiac death. Right coronary artery from the opposite sinus is correlated with a low mortality rate of 0.2% in comparison to left-ACAOS at 6.3% over 20 years in participants of competitive sport. Therefore, strong evidence of ischaemia must be present before opting for surgery. Our pragmatic approach provided in our opinion enough evidence for a conservative treatment strategy.

Major threats to early safety after transcatheter aortic valve implantation in a contemporary cohort of real-world patients

INTRODUCTION

Despite considerable advances in the last decade, major adverse events remain a concern after transcatheter aortic valve implantation (TAVI). The aim of this study was to provide a detailed overview of their underlying causes and contributing factors in order to identify key domains for quality improvement.

METHODS

This observational, prospective registry included all patients undergoing TAVI between 31 December 2015 and 1 January 2020 at the St. Antonius Hospital in Nieuwegein and the University Medical Centre in Utrecht. Outcomes of interest were all-cause mortality, stroke, major bleeding, life-threatening or disabling bleeding, major vascular complications, myocardial infarction, severe acute kidney injury and conduction disturbances requiring permanent pacemaker implantation within 30 days after TAVI, according to the Valve Academic Research Consortium‑2 criteria.

RESULTS

Of the 1250 patients who underwent TAVI in the evaluated period, 146 (11.7%) developed a major complication. In 54 (4.3%) patients a thromboembolic event occurred, leading to stroke in 36 (2.9%), myocardial infarction in 13 (1.0%) and lower limb ischaemia in 11 (0.9%). Major bleeding occurred in 65 (5.2%) patients, most frequently consisting of acute cardiac tamponade (n = 25; 2.0%) and major access-site bleeding (n = 21; 1.7%). Most complications occurred within 1 day of the procedure. Within 30 days a total of 54 (4.3%) patients died, the cause being directly TAVI-related in 30 (2.4%). Of the patients who died from causes that were not directly TAVI-related, 14 (1.1%) had multiple hospital-acquired complications.

CONCLUSION

A variety of underlying mechanisms and causes form a wide spectrum of major threats affecting early safety in 11.7% of patients undergoing TAVI in a contemporary cohort of real-world patients.

Ischemic signs on the post-resuscitation ECG in absence of STEMI is associated with lower survival. A COACT trial's sub-study

Background

The recently published Coronary Angiography after Cardiac arrest (COACT) trial found that urgent coronary angiography did not improve 90-day survival in out-of-hospital cardiac arrest (OHCA) patients without STEMI. The prognostic value of signs of ischemia on the ECG in absence of STEMI, is yet to be determined.

Purpose

To assess whether ischemic ECG patterns such as ST-depression and T-wave inversion are predictors for survival after OHCA in patients without STEMI.

Methods

In the COACT trial, patients with return of spontaneous circulation after OHCA with initial shockable rhythm and absence of ST-segment elevation were included. In this sub-study, the first post-resuscitation ECG recorded at the hospital was analysed for signs of ischemia. Ischemia was defined as ST-depression or T-wave inversion >1mm in ≥2 contiguous leads, or both. Primary endpoint was 90-day survival. Secondary endpoints included angiographic outcomes and left ventricular function assessed by cardiac magnetic resonance imaging or echocardiography.

Results

In total, 552 patients were included in the COACT trial. For this sub-study, 510 OHCA-patients had an ECG available for assessment of whom 340 patients (66.7%) had signs of ischemia on the ECG and 170 patients (33.3%) were without signs of ischemia. Patients with signs of ischemia were significantly older (p=0.003) and more frequently had a history of CAD (p=0.009). Left ventricular ejection fraction was lower in those with signs of ischemia (p=0.007). The number of acute thrombotic occlusions did not differ between groups (p=0.34). Patients with signs of ischemia had a significantly worse 90-day survival compared to patients that showed no signs of ischemia (HR 1.51 (95% CI 1.08–2.12); log-rank p=0.02). Furthermore, larger ST-depression was found to be associated with worse survival (log-rank p=0.01). Neurologic injury was the most common cause of death and its incidence did not differ between the groups (p=0.77).

Conclusion

Signs of ischemia in absence of STEMI on the post-resuscitation ECG is a predictor for worse survival. Furthermore, a correlation was found between the sum of ST-depression and lower survival rate.

Funding Acknowledgement

Type of funding sources: Public Institution(s). Main funding source(s): Research grants of Netherlands Heart institue, Biotronic, AstraZeneca Survival plot signs of ischemia on ECGSurvival plot sum of ST-depression

Costs analysis from a randomized comparison of immediate versus delayed angiography in patients successfully resuscitated after out-of-hospital cardiac arrest

Background

In out-of-hospital cardiac arrest (OHCA) patients without ST-segment elevation, immediate coronary angiography did not improve clinical outcomes when compared to delayed angiography in the Coronary Angiography after Cardiac Arrest (COACT) trial (1,2). Whether one of the two strategies has benefits in terms of healthcare resource use and costs is currently unknown. We assess the healthcare resource use and costs in patients with OHCA.

Methods

521 patients were eligible for a cost consequence analysis. Detailed healthcare resource use and cost-prices were collected from the initial hospital episode and compared between both groups. A generalized model (GLM) with a log link function and a gamma distribution was performed. Generic quality of life was measured with the RAND36 and collected at 12 months follow-up.

Results

Overall total mean costs were similar between both groups (EUR 33575±19612 vs EUR 33880±21044, P=0.86). GLM: (β 0.991 (95% CI 0.894–1.099), P=0.86. Mean procedural costs (CAG and/or PCI, coronary artery bypass graft) were higher in the immediate angiography group (EUR 4384±3447 vs EUR 3028±4220, P<0.001). Costs concerning Intensive Care Unit and ward stay did not show any significant difference. The median for the RAND-36 questionnaire physical component score was 49.2 in the immediate angiography group and 50.4 in the delayed group, P=0.57.

Conclusions

The mean total costs between OHCA patients randomized to an immediate angiography or a delayed invasive strategy were similar. With respect to the higher invasive procedure costs in the immediate group, a strategy awaiting neurological recovery followed by coronary angiography and planned revascularization may be considered.

Funding Acknowledgement

Type of funding sources: Private grant(s) and/or Sponsorship. Main funding source(s): Supported by unrestricted research grants from the Netherlands Heart Institute, Biotronik, and AstraZeneca.

2020 ESC Guidelines on acute coronary syndrome without ST-segment elevation : Recommendations and critical appraisal from the Dutch ACS and Interventional Cardiology working groups

Recently, the European Society of Cardiology (ESC) has updated its guidelines for the management of patients with acute coronary syndrome (ACS) without ST-segment elevation. The current consensus document of the Dutch ACS working group and the Working Group of Interventional Cardiology of the Netherlands Society of Cardiology aims to put the 2020 ESC Guidelines into the Dutch perspective and to provide practical recommendations for Dutch cardiologists, focusing on antiplatelet therapy, risk assessment and criteria for invasive strategy.

The first multicentre study on coronary anomalies in the Netherlands: MuSCAT

Background

Current guidelines on coronary anomalies are primarily based on expert consensus and a limited number of trials. A gold standard for diagnosis and a consensus on the treatment strategy in this patient group are lacking, especially for patients with an anomalous origin of a coronary artery from the opposite sinus of Valsalva (ACAOS) with an interarterial course.

Aim

To provide evidence-substantiated recommendations for diagnostic work-up, treatment and follow-up of patients with anomalous coronary arteries.

Methods

A clinical care pathway for patients with ACAOS was established by six Dutch centres. Prospectively included patients undergo work-up according to protocol using computed tomography (CT) angiography, ischaemia detection, echocardiography and coronary angiography with intracoronary measurements to assess anatomical and physiological characteristics of the ACAOS. Surgical and functional follow-up results are evaluated by CT angiography, ischaemia detection and a quality-of-life questionnaire. Patient inclusion for the first multicentre study on coronary anomalies in the Netherlands started in 2020 and will continue for at least 3 years with a minimum of 2 years of follow-up. For patients with a right or left coronary artery originating from the pulmonary artery and coronary arteriovenous fistulas a registry is maintained.

Results

Primary outcomes are: (cardiac) death, myocardial ischaemia attributable to the ACAOS, re-intervention after surgery and intervention after initially conservative treatment. The influence of work-up examinations on treatment choice is also evaluated.

Conclusions

Structural evidence for the appropriate management of patients with coronary anomalies, especially (interarterial) ACAOS, is lacking. By means of a structured care pathway in a multicentre setting, we aim to provide an evidence-based strategy for the diagnostic evaluation and treatment of this patient group.

Supplementary Information

The online version of this article (10.1007/s12471-021-01556-9) contains supplementary material, which is available to authorized users.

Diagnostic performance and clinical implications for enhancing a hybrid quantitative flow ratio and fractional flow reserve revascularization decision making strategy

Background

Fractional flow reserve (FFR) adoption persists low mainly due to procedural and operator related factors as well as costs. An alternative for FFR, quantitative flow ratio (QFR) achieves a high accuracy mainly outside the intermediate zone without the need for hyperemia and wire-use. Currently, no outcome trials assess the role of QFR in the guidance of revascularization. Therefore, we evaluate a QFR-FFR hybrid strategy in which FFR is measured inside of the intermediate zone.

Methods

This retrospective multi-center study included consecutive patients who underwent both invasive coronary angiography and FFR in the participating centers. QFR was calculated for all vessels in which FFR was measured. Diagnostic performance of QFR was assessed using an FFR cut-off of 0.80 as reference standard. The QFR-FFR hybrid approach was modeled using the intermediate zone of 0.77 to 0.87 assuming that lesions within the intermediate zone follow the FFR binary cutoff.

Results

In total, 381 vessels in 289 patients were analyzed. The sensitivity, specificity and accuracy on a per vessel-based analysis were 84.6%, 86.3% and 85.6% for QFR and 91.1%, 95.3% and 93.4% for the QFR-FFR hybrid approach. The diagnostic accuracy of QFR-FFR hybrid strategy with invasive FFR measurement is 93.4% and results in a FFR reduction of 56.7%.

Conclusion

QFR has a good correlation and agreement with invasive FFR and a high diagnostic accuracy. A hybrid QFR-FFR approach could extend the use of QFR and reduces the proportion of invasive FFR-measurements needed while maintaining a high accuracy.

Hybrid QFR-FFR strategy

Funding Acknowledgement

Type of funding source: None

Direct comparison of predictive performance of PRECISE-DAPT versus PARIS versus CREDO-Kyoto: a subanalysis of the ReCre8 trial

Background

Multiple scores have been proposed to guide risk stratification after percutaneous coronary intervention. This study assessed the performance of the PRECISE-DAPT, PARIS and CREDO-Kyoto risk scores to predict post-discharge ischaemic or bleeding events.

Methods

A total of 1491 patients treated with latest-generation drug-eluting stent implantation were evaluated. Risk scores for post-discharge ischaemic or bleeding events were calculated and directly compared. Prognostic performance of both risk scores was assessed with calibration, Harrell’s c‑statistics net reclassification index and decision curve analyses.

Results

Post-discharge ischaemic events occurred in 56 patients (3.8%) and post-discharge bleeding events in 34 patients (2.3%) within the first year after the invasive procedure. C‑statistics for the PARIS ischaemic risk score was marginal (0.59, 95% confidence interval (CI) 0.51–0.68), whereas the CREDO-Kyoto ischaemic risk score was moderate (0.68, 95% CI 0.60–0.75). With regard to post-discharge bleeding events, CREDO-Kyoto displayed moderate discrimination (c-statistic 0.67, 95% CI 0.56–0.77), whereas PRECISE-DAPT (0.59, 95% CI 0.48–0.69) and PARIS (0.55, 95% CI 0.44–0.65) had a marginal discriminative capacity. Net reclassification index and decision curve analysis favoured CREDO-Kyoto-derived bleeding risk assessment.

Conclusion

In this contemporary all-comer population, PARIS and PRECISE-DAPT risk scores were not resilient to independent testing for post-discharge bleeding events. CREDO-Kyoto-derived risk stratification was associated with a moderate predictive capability for post-discharge ischaemic or bleeding events. Future studies are warranted to improve risk stratification with more focus on robustness and rigorous testing.

Electronic supplementary material

The online version of this article (10.1007/s12471-020-01486-y) contains supplementary material, which is available to authorized users.

Invasive coronary physiology: a Dutch tradition

Invasive coronary physiology has been applied since the early days of percutaneous transluminal coronary angioplasty, and has become a rapidly emerging field of research. Many physiology indices have been developed, tested in clinical studies, and are now applied in daily clinical practice. Recent clinical practice guidelines further support the use of advanced invasive physiology methods to optimise the diagnosis and treatment of patients with acute and chronic coronary syndromes. This article provides a succinct review of the history of invasive coronary physiology, the basic concepts of currently available physiological parameters, and will particularly highlight the Dutch contribution to this field of invasive coronary physiology.

Safety and efficacy of stenting for aortic arch hypoplasia in patients with coarctation of the aorta

Background

Despite a successful repair procedure for coarctation of the aorta (CoA), up to two-thirds of patients remain hypertensive. CoA is often seen in combination with abnormal aortic arch anatomy and morphology. This might be a substrate for persistent hypertension. Therefore, we performed endovascular aortic arch stent placement in patients with CoA and concomitant aortic arch hypoplasia or gothic arch morphology. The goal of this retrospective analysis was to investigate the safety and efficacy of aortic arch stenting.

Methods

A retrospective analysis was performed in patients who underwent stenting of the aortic arch at the University Medical Center Utrecht. Measurements collected included office blood pressure, use of antihypertensive medication, invasive peak-to-peak systolic pressure over the arch, and aortic diameters on three-dimensional angiography. Data on follow-up were obtained at the date of most recent outpatient visit.

Results

Twelve patients underwent stenting of the aortic arch. Mean follow-up duration was 14 ± 11 months. Mean peak-to-peak gradient across the arch decreased from 39 ± 13 mm Hg to 7 ± 8 mm Hg directly after stenting (p < 0.001). There were no major procedural complications. Mean systolic blood pressure decreased from 145 ± 16 mm Hg at baseline to 128 ± 9 mm Hg at latest follow-up (p = 0.014).

Conclusion

This retrospective study shows that stenting of the aortic arch is successful when carried out in a state-of-the-art manner. A direct optimal angiographic and haemodynamic result was shown. No major complications occurred during or after the procedure. At short- to medium-term follow-up a decrease in mean systolic blood pressure was observed.

P3856Timing and associated predictors of onset of new conduction disturbances requiring permanent pacemaker implantation after transcatheter aortic valve implantation

Objectives

This study aimed to investigate the onset and the associated predictors of new conduction disturbances (CDs) requiring permanent pacemaker implantation (PPI) after transcatheter aortic valve implantation (TAVI).

Background

The onset and associated predictors of onset of new CDs leading to PPI are still unknown. However, these are essential for safe and early discharge. Currently, these CDs lead to prolonged post-procedural monitoring after TAVI, limiting early discharge possibilities.

Methods

We retrospectively analyzed data from five centers in Europe. Post-TAVI electrocardiograms and telemetry data were evaluated to identify the onset of new CD in all patients who required a PPI within 30 days after TAVI. Early onset CDs were defined as within 48 hours after procedure, and late onset CDs as after 48 hours.

Results

A total of 2,804 patients were included for analysis. The PPI rate was 11%, of which 18% was due to late onset (>48h) CDs. Independent predictors for late onset CDs requiring PPI were pre-existing non-specific intraventricular conduction delay (IVCD), pre-existing right bundle branch block (RBBB), self-expandable valves, and predilation (Figure). Patients with a balloon-expandable valve without predilation did not develop CDs requiring PPI after 48 hours.

Figure 1

Conclusions

Associated predictors of late onset conduction disturbances leading to PPI after TAVI were pre-existing IVCD, pre-existing RBBB, the use of self-expandable valves, and predilation. Patients without CDs in the first 48 hours after TAVI and without risk factors for late onset CDs requiring PPI are possible candidates for early discharge after 48 hours.

P5620Clinical and hemodynamic determinants of coronary flow reserve in non-obstructed coronary arteries - A patient level pooled analysis of the DEBATE and ILIAS studies

Aim

Coronary Flow Reserve (CFR) is a valuable physiological index for the assessment of myocardial flow impairment due to focal or microcirculatory coronary artery disease (CAD). Coronary flow capacity (CFC) is another flow-based concept in diagnosing ischemic heart disease (IHD), based on hyperemic average peak velocity (hAPV) and CFR. We evaluated clinical and hemodynamic factors which potentially influence CFR and CFC in non-obstructed coronary arteries.

Methods

We analysed CFR and CFC of 396 non-obstructed vessels of patients from two large multi-center trials (DEBATE and ILIAS) with stable CAD who were scheduled for percutaneous coronary intervention (PCI). Doppler flow measurements were performed after inducing hyperemia with either intracoronary or intravenous infusion of adenosine.

Results

Akaike's Information Criterion (AIC) revealed the parameters age, female gender, a history of myocardial infarction, hypercholesterolemia, current or previous smoking and rate pressure product (RPP) as independent predictors in the best model of fit for CFR in an angiographically non-obstructed vessel. After multivariate regression analysis age, female gender and RPP remained as determinants of CFR in angiographically non-obstructed vessels. Subsequently, ordered logistic regression analysis revealed that age is associated with a worse CFC.

Conclusion

Clinical and hemodynamic parameters are associated with CFR and to a lesser extent CFC in an angiographically non-obstructed coronary artery. CFC is less sensitive to variations in clinical and hemodynamic parameters than CFR and therefore a promising tool in contemporary clinical decision making in the cardiac catheterization laboratory.

Acknowledgement/Funding

DEBATE: Cardiometrics INC. ILIAS: Dutch Health Insurance Board; RADI Medical Systems, Uppsala, Sweden; and Endosonics, Rancho Cordova, CA.

Incidence, angiographic and clinical predictors, and impact of stent thrombosis: a 6-year survey of 6,545 consecutive patients

Objective

We sought to determine the incidence, angiographic predictors, and impact of stent thrombosis (ST).

Background

Given the high mortality after ST, this study emphasises the importance of ongoing efforts to identify angiographic predictors of ST.

Methods

All consecutive patients with angiographically confirmed ST between 2010 and 2016 were 1:4 matched for (1) percutaneous coronary intervention (PCI) indication and (2) index date ±6 weeks to randomly selected controls. Index PCI angiograms were reassessed by two independent cardiologists. A multivariable conditional logistic regression model was built to identify independent predictors of ST.

Results

Of 6,545 consecutive patients undergoing PCI, 55 patients [0.84%, 95% confidence interval (CI) 0.63–1.10%] presented with definite ST. Multivariable logistic regression identified dual antiplatelet therapy (DAPT) non-use as the strongest predictor of ST (odds ratio (OR) 10.9, 95% CI 2.47–48.5, p < 0.001), followed by: stent underexpansion (OR 5.70, 95% CI 2.39–13.6, p < 0.001), lesion complexity B2/C (OR 4.32, 95% CI 1.43–13.1, p = 0.010), uncovered edge dissection (OR 4.16, 95% CI 1.47–11.8, p = 0.007), diabetes mellitus (OR 3.23, 95% CI 1.25–8.36, p = 0.016), and residual coronary artery disease at the stent edge (OR 3.02, 95% CI 1.02–8.92, p = 0.045). ST was associated with increased rates of mortality as analysed by Kaplan-Meier estimates (27.3 vs 11.3%, p_log-rank < 0.001) and adjusted Cox proportional-hazard regression (hazard ratio 2.29, 95% CI 1.03–5.10, p = 0.042).

Conclusions

ST remains a serious complication following PCI with a high rate of mortality. DAPT non-use was associated with the highest risk of ST, followed by various angiographic parameters and high lesion complexity.

Electronic supplementary material

The online version of this article (10.1007/s12471-019-1253-2) contains supplementary material, which is available to authorized users.

Haemodynamic and functional consequences of the iatrogenic atrial septal defect following Mitraclip therapy

Percutaneous MitraClip placement for treatment of severe mitral regurgitation in high surgical risk patients is a commonly performed procedure and requires a transseptal puncture to reach the left atrium. The resulting iatrogenic atrial septal defect (iASD) is not routinely closed, yet the haemodynamic and functional consequences of a persisting defect are not fully understood. Despite positive effects such as acute left atrial pressure relief, persisting iASDs are associated with negative consequences, namely significant bidirectional shunting and subsequent worse clinical outcome. Percutaneous closure of the iASD may therefore be desirable in selected cases. In this review we discuss the available literature on this matter.

Safety and efficacy of a device to narrow the coronary sinus for the treatment of refractory angina: A single-centre real-world experience

Objective

The coronary sinus Reducer is a recently introduced device to treat patients with severe angina symptoms refractory to optimal medical therapy and not amenable for conventional revascularisation. We aimed to assess the safety and efficacy of the Reducer in a real-world cohort of patients with refractory angina.

Methods

This is a single-centre retrospective registry. Patients with severe angina symptoms, objective evidence of myocardial ischaemia using any adequate non-invasive modality and without options for conventional revascularisation were regarded eligible for Reducer implantation.

Results

Twenty-three patients (74 % male, mean age 70 ± 8 years, 91.3 % previous bypass surgery, 82.6 % previous percutaneous intervention, 47.8 % previous myocardial infarction, 52.2 % diabetes mellitus) underwent Reducer implantation. The safety endpoint (successful implantation of the first device without device-related adverse events) was met in all patients. After a median follow-up of 9 (8–14) months the efficacy (any reduction in Canadian Cardiovascular Society (CCS) class and revascularisation-free survival) was reached in 17 patients (74 %): 8 patients (34.8 %) improved by 1 CCS class, 7 (30.4 %) by 2 CCS classes and 2 (8.7 %) by 3 CCS classes. One patient died 4 months after implantation because of progressive heart failure (not associated with Reducer implantation).

Conclusion

In this single-centre real-world experience, Reducer implantation was safe and demonstrated excellent clinical efficacy in the treatment of refractory angina at mid-term follow-up.

Safety and long-term effects of renal denervation: Rationale and design of the Dutch registry

BACKGROUND

Percutaneous renal denervation (RDN) has recently been introduced as a treatment for therapy-resistant hypertension. Also, it has been suggested that RDN may be beneficial for other conditions characterised by increased sympathetic nerve activity. There are still many uncertainties with regard to efficacy, safety, predictors for success and long-term effects. To answer these important questions, we initiated a Dutch RDN registry aiming to collect data from all RDN procedures performed in the Netherlands.

METHODS

The Dutch RDN registry is an ongoing investigator-initiated, prospective, multicentre cohort study. Twenty-six Dutch hospitals agreed to participate in this registry. All patients who undergo RDN, regardless of the clinical indication or device that is used, will be included. Data are currently being collected on eligibility and screening, treatment and follow-up.

RESULTS

Procedures have been performed since August 2010. At present, data from 306 patients have been entered into the database. The main indication for RDN was hypertension (n = 302, 99%). Patients had a mean office blood pressure of 177/100 (±29/16) mmHg with a median use of three (range 0-8) blood pressure lowering drugs. Mean 24-hour blood pressure before RDN was 157/93 (±18/13) mmHg. RDN was performed with different devices, with the Simplicity™ catheter currently used most frequently.

CONCLUSION

Here we report on the rationale and design of the Dutch RDN registry. Enrolment in this investigator-initiated study is ongoing. We present baseline characteristics of the first 306 participants.

Renal denervation for the treatment of hypertension: the Dutch consensus

Since 2010, renal denervation (RDN) is being performed in the Netherlands. To make sure RDN is implemented with care and caution in the Netherlands, a multidisciplinary Working Group has been set up by the Dutch Society of Cardiology (NVVC). The main aim of this Working Group was to establish a consensus document that can be used as a guide for implementation of RDN in the Netherlands. This consensus document was prepared in consultation with the Dutch Association of Internal Medicine (NIV) and the Dutch Society of Radiology (NVVR).

Renal denervation: a new treatment option in resistant arterial hypertension

Hypertension is one of the most prevalent cardiovascular risk factors. Despite this high prevalence and a broad availability of effective pharmaceutical agents, a significant proportion of patients do not reach treatment goals. Partly this can be explained by secondary causes of hypertension or non-compliance of patients. Nevertheless, a subgroup of patients can be diagnosed with 'resistant hypertension'. Activation of the sympathetic nervous system is known to be an important factor in the development and progression of systemic hypertension. In this context, a percutaneous, catheter-based approach has been developed using radiofrequency energy to disrupt renal sympathetic nerves. The first studies have shown this technique to be safe, illustrated by a lack of vascular or renal injury. More importantly, catheter-based renal nerve ablation resulted in a significant reduction in blood pressure on top of traditional medical therapy. Additional to the encouraging effects shown on hypertension, a positive influence of this intervention in other conditions, characterised by sympathetic overactivation, may be expected. Though this technique seems promising, further studies are needed to address long-term safety and efficacy of renal denervation in hypertension and other disease states.

Infective complications after transcatheter aortic valve implantation: results from a single centre

After its first introduction in 2002, transcatheter aortic valve implantation (TAVI) has continuously gained more foothold for the treatment of severe aortic stenosis and is nowadays a viable treatment option for inoperable patients or patients at high risk for conventional surgical aortic valve replacement. Although ideally carried out in a so-called hybrid room, incorporating both the strict hygiene and advanced life support possibilities of the operating theatre and the imaging and percutaneous arsenal of the catheterisation suite, in most centres TAVI is at present performed in the catheterisation laboratory. This may raise concern about an increased risk of infection, since there the criteria that are applied regarding disinfection and sterilisation are not as stringent as those of the operating theatre. Therefore, we retrospectively assessed the number of infective complications in patients undergoing TAVI in the catheterisation lab of our institution. Eleven out of 73 patients developed a postprocedural infection, one of which could be attributed to the procedure itself, being superinfection of a surgical groin cut-down. Our conclusion is that percutaneous aortic valve implantation in a catheterisation laboratory is not associated with an increased risk of infective complications.

CD44 Regulates Arteriogenesis in Mice and Is Differentially Expressed in Patients With Poor and Good Collateralization

Background— Arteriogenesis refers to the development of collateral conductance arteries and is orchestrated by circulating monocytes, which invade growing collateral arteries and act as suppliers of cytokines and growth factors. CD44 glycoproteins are involved in leukocyte extravasation but also in the regulation of growth factor activation, stability, and signaling. Here, we explored the role of CD44 during arteriogenesis.

Methods and Results— CD44 expression increases strongly during collateral artery growth in a murine hind-limb model of arteriogenesis. This CD44 expression is of great functional importance, because arteriogenesis is severely impaired in CD44 −/− mice (wild-type, 54.5±14.9% versus CD44 −/− , 24.1±9.2%, P <0.001). The defective arteriogenesis is accompanied by reduced leukocyte trafficking to sites of collateral artery growth (wild-type, 29±12% versus CD44 −/− , 18±7% CD11b-positive cells/square, P <0.01) and reduced expression of fibroblast growth factor-2 and platelet-derived growth factor-B protein. Finally, in patients with single-vessel coronary artery disease, the maximal expression of CD44 on activated monocytes is reduced in case of impaired collateral artery formation (poor collateralization, 1764±572 versus good collateralization, 2817±1029 AU, P <0.05).

Conclusions— For the first time, the pivotal role of CD44 during arteriogenesis is shown. The expression of CD44 increases during arteriogenesis, and the deficiency of CD44 severely impedes arteriogenesis. Maximal CD44 expression on isolated monocytes is decreased in patients with a poor collateralization compared with patients with a good collateralization.

Local monocyte chemoattractant protein-1 therapy increases collateral artery formation in apolipoprotein E-deficient mice but induces systemic monocytic CD11b expression, neointimal formation, and plaque progression

Monocyte chemoattractant protein-1 (MCP-1) stimulates the formation of a collateral circulation on arterial occlusion. The present study served to determine whether these proarteriogenic properties of MCP-1 are preserved in hyperlipidemic apolipoprotein E-deficient (apoE-/-) mice and whether it affects the systemic development of atherosclerosis. A total of 78 apoE-/- mice were treated with local infusion of low-dose MCP-1 (1 microg/kg per week), high-dose MCP-1 (10 microg/kg per week), or PBS as a control after unilateral ligation of the femoral artery. Collateral hindlimb flow, measured with fluorescent microspheres, significantly increased on a 1-week high-dose MCP-1 treatment (PBS 22.6+/-7.2%, MCP-1 31.3+/-10.3%; P<0.05). These effects were still present 2 months after the treatment (PBS 44.3+/-4.6%, MCP-1 56.5+/-10.4%; P<0.001). The increase in collateral flow was accompanied by an increase in the number of perivascular monocytes/macrophages on MCP-1 treatment. However, systemic CD11b expression by monocytes also increased, as did monocyte adhesion at the aortic endothelium and neointimal formation (intima/media ratio, 0.097+/-0.011 [PBS] versus 0.257+/-0.022 [MCP-1]; P<0.0001). Moreover, Sudan IV staining revealed an increase in aortic atherosclerotic plaque surface (24.3+/-5.2% [PBS] versus 38.2+/-9.5% [MCP-1]; P<0.01). Finally, a significant decrease in the percentage of smooth muscle cells was found in plaques (15.0+/-5.2% [PBS] versus 5.8+/-2.3% [MCP-1]; P<0.001). In conclusion, local infusion of MCP-1 significantly increases collateral flow on femoral artery ligation in apoE-/- mice up to 2 months after the treatment. However, the local treatment did not preclude systemic effects on atherogenesis, leading to increased atherosclerotic plaque formation and changes in cellular content of plaques.

Effects of local MCP-1 protein therapy on the development of the collateral circulation and atherosclerosis in Watanabe hyperlipidemic rabbits

OBJECTIVE

The objective of our study was to quantify the arteriogenic potency of Monocyte Chemoattractant Protein-1 (MCP-1) under hyperlipidemic conditions. Additionally, we aimed to determine the effects of locally applied MCP-1 on systemic serum lipid levels as well as on atherosclerosis.

METHODS

A total of sixty-four Watanabe rabbits was treated with either low dose MCP-1 (1 microg/kg/week), high dose MCP-1 (3.3 microg/kg/week) or PBS as a control substance. Substances were applied directly into the collateral circulation via an osmotic minipump with the catheter placed in the proximal stump of the ligated femoral artery. Either 1 week or 6 months after initiation of the treatment X-ray angiography was performed as well as measurements of collateral conductance using fluorescent microspheres. The extent of atherosclerosis was quantified in whole aortas using Sudan IV staining.

RESULTS

One week after ligation of the femoral artery a significant increase in collateral conductance was observed in animals treated with high dose MCP-1 (control: 2.2+/-0.8 ml/min/100 mmHg vs. MCP-1 high dose: 8.9+/-2.0 ml/min/100 mmHg, P<0.05). Six months after femoral artery ligation no differences were found between the treated and the control group (PBS; 44.9+/-11.6 ml/min/100 mmHg, MCP-1; 47.8+/-11.5 ml/min/100 mmHg, P=NS). No influence was found on serum lipids or on the development of atherosclerosis in the present model.

CONCLUSION

MCP-1 accelerates arteriogenesis upon femoral artery ligation under hyperlipidemic conditions. Six months after treatment these pro-arteriogenic effects of MCP-1 can no longer be observed. The present data do not show an effect of local MCP-1 treatment on serum lipids or on atherosclerosis. It should be noted however that a high standard deviation was observed for the data on atherosclerotic surface area, necessitating additional experiments in a different model of atherosclerosis.

Coronary flow velocity reserve after percutaneous interventions is predictive of periprocedural outcome

BACKGROUND

Because heterogeneous results have been reported, we assessed coronary flow velocity changes in individuals who underwent percutaneous transluminal coronary angioplasty (PTCA) and examined their impact on clinical outcome.

METHODS AND RESULTS

As part of the Doppler Endpoints Balloon Angioplasty Trial Europe (DEBATE) II study, 379 patients underwent Doppler flow-guided angioplasty. All patients were evaluated according to their coronary flow velocity reserve (CFVR) results (> or =2.5 or < 2.5) at the end of the procedure. A CFVR < 2.5 after angioplasty was associated with an elevated baseline blood flow velocity in both the target artery and reference artery. CFVR before PTCA and CFVR in the reference artery were independent predictors of an optimal CFVR after balloon angioplasty (CFVR before PTCA: odds ratio [OR], 2.26; 95% confidence interval [CI], 1.57 to 3.24; CFVR in reference artery: OR, 1.90; 95% CI, 1.21 to 2.98; both P<0.001) and stent implantation (before PTCA: OR, 2.54; 95% CI, 1.47 to 4.36; reference artery: OR, 1.97; 95% CI, 1.07 to 3.87; both P<0.05). A low CFVR at the end of the procedure was an independent predictor of major adverse cardiac events (MACE) at 30 days (OR, 4.71; 95% CI, 1.14 to 25.92; P=0.034) and at 1 year (OR, 2.06; 95% CI, 1.16 to 3.66; P=0.014). After excluding MACE at 30 days, no difference in MACE at 1 year was observed between the patients with and without a CFVR < 2.5 at the end of the procedure.

CONCLUSIONS

A low postprocedural CFVR was associated with a worse periprocedural outcome (which was related to microcirculatory disturbances), but there was no significant difference at late follow-up.

The immediate and long-term effect of optimal balloon angioplasty on the absolute coronary blood flow velocity reserve. A subanalysis of the DEBATE study. Doppler Endpoints Balloon Angioplasty Trial Europe

BACKGROUND

There are limited data regarding the immediate and long-term effect of balloon angioplasty on the coronary flow reserve evaluated in a multicentre setting.

METHODS AND RESULTS

A total of 86 patients with one-vessel disease and normal left ventricular function were analysed before and after optimal balloon angioplasty (diameter stenosis <35%) and at 6-month follow-up. Coronary flow reserve was assessed with a Doppler guide wire. A low coronary flow reserve (<or=2.5) after PTCA, due to an increased baseline blood flow velocity, was encountered in 42 of the 86 patients (49%). Recurrence of angina and target lesion revascularization were more frequent in these patients than in patients with a coronary flow reserve >2.5 (46% vs 23% and 36% vs 16%, respectively; P<0.05) due to a trend towards restenosis (29% vs 16%; P=0.15) or a low coronary flow reserve at follow-up due to persistent elevated baseline blood flow velocity. Patients without restenosis showed a decrease or increase of coronary flow reserve during follow-up, determined by alterations of hyperaemic blood flow velocity.

CONCLUSIONS

Patients with an impaired coronary flow reserve directly after optimal balloon angioplasty showed a higher target lesion revascularization rate compared to patients with a coronary flow reserve >2.5. This patient group consists of patients prone to develop restenosis, while other patients are characterized by a persistently low coronary flow reserve, probably secondary to disturbed autoregulation and/or diffuse mild coronary atherosclerosis. Coronary flow reserve alterations in patients without restenosis were related to changes in hyperaemic blood flow velocity, suggesting that this phenomenon relates to epicardial remodelling.

Regulation of the Mycobacterium tuberculosis hypoxic response gene encoding alpha -crystallin

Unlike many pathogens that are overtly toxic to their hosts, the primary virulence determinant of Mycobacterium tuberculosis appears to be its ability to persist for years or decades within humans in a clinically latent state. Since early in the 20th century latency has been linked to hypoxic conditions within the host, but the response of M. tuberculosis to a hypoxic signal remains poorly characterized. The M. tuberculosis alpha-crystallin (acr) gene is powerfully and rapidly induced at reduced oxygen tensions, providing us with a means to identify regulators of the hypoxic response. Using a whole genome microarray, we identified >100 genes whose expression is rapidly altered by defined hypoxic conditions. Numerous genes involved in biosynthesis and aerobic metabolism are repressed, whereas a high proportion of the induced genes have no known function. Among the induced genes is an apparent operon that includes the putative two-component response regulator pair Rv3133c/Rv3132c. When we interrupted expression of this operon by targeted disruption of the upstream gene Rv3134c, the hypoxic regulation of acr was eliminated. These results suggest a possible role for Rv3132c/3133c/3134c in mycobacterial latency.

[Angiogenesis and arteriogenesis; the long road from concept to clinical application]

In patients with obstructive artery disease, two different forms of compensatory vessel growth occur; angiogenesis and arteriogenesis. Angiogenesis is the formation of a capillary network, through the activation and proliferation of endothelial cells in ischaemic tissue. Arteriogenesis is the transformation of pre-existent collateral arterioles into functional collateral arteries. Circulating blood cells, especially monocytes, play an important role in the arteriogenesis process. Animal experiments have demonstrated that local treatment with monocyte chemoattractant protein-1 results in an elevated accumulation of monocytes/macrophages and an increased growth of collateral vessels. The stimulation of arteriogenesis will probably result in a greater increase in blood flow to the ischaemic tissue, than the stimulation of angiogenesis. This can be explained by the difference in diameter between the collateral vessels formed in arteriogenesis and the capillaries formed in angiogenesis. Research to the efficacy of growth factors that stimulate the arteriogenesis process is still at an experimental stage. The stimulation of arteriogenesis is studied in models of both peripheral and coronary obstructive disease.

Stimulation of arteriogenesis; a new concept for the treatment of arterial occlusive disease

After birth two forms of vessel growth can be observed; angiogenesis and arteriogenesis. Angiogenesis refers to the formation of capillary networks. Arteriogenesis refers to the growth of preexistent collateral arterioles leading to formation of large conductance arteries that are well capable to compensate for the loss of function of occluded arteries. The process of arteriogenesis is initiated when shear stresses increase in the preexistent collateral pathways upon narrowing of a main artery. The increased shear stress leads to an upregulation of cell adhesion molecules for circulating monocytes, which accumulate subsequently around the proliferating arteries and provide the several required cytokines and growth factors. Several strategies are currently tested for their potential to stimulate the process of arteriogenesis. These strategies focus either at shear stress, at direct stimulation of endothelial and smooth muscle cell growth or at the monocytic pathway and promising results were obtained from experimental studies. However, some important questions remain to be answered before arteriogenesis can be brought from bench to bedside.