recruIT: A cloud-native clinical trial recruitment support system based on Health Level 7 Fast Healthcare Interoperability Resources (HL7 FHIR) and the Observational Medical Outcomes Partnership Common Data Model (OMOP CDM)

BACKGROUND

Clinical trials (CTs) are foundational to the advancement of evidence-based medicine and recruiting a sufficient number of participants is one of the crucial steps to their successful conduct. Yet, poor recruitment remains the most frequent reason for premature discontinuation or costly extension of clinical trials.

METHODS

We designed and implemented a novel, open-source software system to support the recruitment process in clinical trials by generating automatic recruitment recommendations. The development is guided by modern, cloud-native design principles and based on Health Level 7 (HL7) Fast Healthcare Interoperability Resources (FHIR) as an interoperability standard with the Observational Medical Outcomes Partnership (OMOP) Common Data Model (CDM) being used as a source of patient data. We evaluated the usability using the system usability scale (SUS) after deploying the application for use by study personnel.

RESULTS

The implementation is based on the OMOP CDM as a repository of patient data that is continuously queried for possible trial candidates based on given clinical trial eligibility criteria. A web-based screening list can be used to display the candidates and email notifications about possible new trial participants can be sent automatically. All interactions between services use HL7 FHIR as the communication standard. The system can be installed using standard container technology and supports more sophisticated deployments on Kubernetes clusters. End-users (n = 19) rated the system with a SUS score of 79.9/100.

CONCLUSION

We contribute a novel, open-source implementation to support the patient recruitment process in clinical trials that can be deployed using state-of-the art technologies. According to the SUS score, the system provides good usability.

Effectiveness of IT-supported patient recruitment: study protocol for an interrupted time series study at ten German university hospitals

BACKGROUND

As part of the German Medical Informatics Initiative, the MIRACUM project establishes data integration centers across ten German university hospitals. The embedded MIRACUM Use Case "Alerting in Care - IT Support for Patient Recruitment", aims to support the recruitment into clinical trials by automatically querying the repositories for patients satisfying eligibility criteria and presenting them as screening candidates. The objective of this study is to investigate whether the developed recruitment tool has a positive effect on study recruitment within a multi-center environment by increasing the number of participants. Its secondary objective is the measurement of organizational burden and user satisfaction of the provided IT solution.

METHODS

The study uses an Interrupted Time Series Design with a duration of 15 months. All trials start in the control phase of randomized length with regular recruitment and change to the intervention phase with additional IT support. The intervention consists of the application of a recruitment-support system which uses patient data collected in general care for screening according to specific criteria. The inclusion and exclusion criteria of all selected trials are translated into a machine-readable format using the OHDSI ATLAS tool. All patient data from the data integration centers is regularly checked against these criteria. The primary outcome is the number of participants recruited per trial and week standardized by the targeted number of participants per week and the expected recruitment duration of the specific trial. Secondary outcomes are usability, usefulness, and efficacy of the recruitment support. Sample size calculation based on simple parallel group assumption can demonstrate an effect size of d=0.57 on a significance level of 5% and a power of 80% with a total number of 100 trials (10 per site). Data describing the included trials and the recruitment process is collected at each site. The primary analysis will be conducted using linear mixed models with the actual recruitment number per week and trial standardized by the expected recruitment number per week and trial as the dependent variable.

DISCUSSION

The application of an IT-supported recruitment solution developed in the MIRACUM consortium leads to an increased number of recruited participants in studies at German university hospitals. It supports employees engaged in the recruitment of trial participants and is easy to integrate in their daily work.

Evaluation of Eligibility Criteria Relevance for the Purpose of IT-Supported Trial Recruitment: Descriptive Quantitative Analysis

BACKGROUND

Clinical trials (CTs) are crucial for medical research; however, they frequently fall short of the requisite number of participants who meet all eligibility criteria (EC). A clinical trial recruitment support system (CTRSS) is developed to help identify potential participants by performing a search on a specific data pool. The accuracy of the search results is directly related to the quality of the data used for comparison. Data accessibility can present challenges, making it crucial to identify the necessary data for a CTRSS to query. Prior research has examined the data elements frequently used in CT EC but has not evaluated which criteria are actually used to search for participants. Although all EC must be met to enroll a person in a CT, not all criteria have the same importance when searching for potential participants in an existing data pool, such as an electronic health record, because some of the criteria are only relevant at the time of enrollment.

OBJECTIVE

In this study, we investigated which groups of data elements are relevant in practice for finding suitable participants and whether there are typical elements that are not relevant and can therefore be omitted.

METHODS

We asked trial experts and CTRSS developers to first categorize the EC of their CTs according to data element groups and then to classify them into 1 of 3 categories: necessary, complementary, and irrelevant. In addition, the experts assessed whether a criterion was documented (on paper or digitally) or whether it was information known only to the treating physicians or patients.

RESULTS

We reviewed 82 CTs with 1132 unique EC. Of these 1132 EC, 350 (30.9%) were considered necessary, 224 (19.8%) complementary, and 341 (30.1%) total irrelevant. To identify the most relevant data elements, we introduced the data element relevance index (DERI). This describes the percentage of studies in which the corresponding data element occurs and is also classified as necessary or supplementary. We found that the query of "diagnosis" was relevant for finding participants in 79 (96.3%) of the CTs. This group was followed by "date of birth/age" with a DERI of 85.4% (n=70) and "procedure" with a DERI of 35.4% (n=29).

CONCLUSIONS

The distribution of data element groups in CTs has been heterogeneously described in previous works. Therefore, we recommend identifying the percentage of CTs in which data element groups can be found as a more reliable way to determine the relevance of EC. Only necessary and complementary criteria should be included in this DERI.

Implementation of inclusion and exclusion criteria in clinical studies in OHDSI ATLAS software

Clinical trials are essential parts of a medical study process, but studies are often cancelled due to a lack of participants. Clinical Trial Recruitment Support Systems are systems that help to increase the number of participants by seeking more suitable subjects. The software ATLAS (developed by Observational Health Data Sciences and Informatics) can support the launch of a clinical trial by building cohorts of patients who fulfill certain criteria. The correct use of medical classification systems aiming at clearly defined inclusion and exclusion criteria in the studies is an important pillar of this software. The aim of this investigation was to determine whether ATLAS can be used in a Clinical Trial Recruitment Support System to portray the eligibility criteria of clinical studies. Our analysis considered the number of criteria feasible for integration with ATLAS and identified its strengths and weaknesses. Additionally, we investigated whether nonrepresentable criteria were associated with the utilized terminology systems. We analyzed ATLAS using 223 objective eligibility criteria from 30 randomly selected trials conducted in the last 10 years. In the next step, we selected appropriate ICD, OPS, LOINC, or ATC codes to feed the software. We classified each criterion and study based on its implementation capability in the software, ensuring a clear and logical progression of information. Based on our observations, 51% of the analyzed inclusion criteria were fully implemented in ATLAS. Within our selected example set, 10% of the studies were classified as fully portrayable, and 73% were portrayed to some extent. Additionally, we conducted an evaluation of the software regarding its technical limitations and interaction with medical classification systems. To improve and expand the scope of criteria within a cohort definition in a practical setting, it is recommended to work closely with personnel involved in the study to define the criteria precisely and to carefully select terminology systems. The chosen criteria should be combined according to the specific setting. Additional work is needed to specify the significance and amount of the extracted criteria.

RD-MON - Building a Rare Disease Monitor to Enhance Awareness for Patients with Rare Diseases in Intensive Care

Rare diseases are commonly defined by an incidence of less than 5/10000 inhabitants. There are some 8000 different rare diseases known. So even if a single rare disease is seldom, together they pose a relevant problem for diagnosis and treatment. This is especially true if a patient is treated for another common disease. University hospital of Gießen is part of the CORD-MI Project on rare diseases within the German Medical Informatics Initiative (MII) and a member of the MIRACUM consortium within the MII. As part of the ongoing Development for a clinical research study monitor within the use case 1 of MIRACUM, the study monitor has been configured to detect patients with rare diseases during their routine clinical encounters. The goal was to send a documentation request to the corresponding patient chart within the patient data management system for extended disease documentation to enhance clinical awareness for the patients' potential problems. The project was started in late 2022 and has so far been successfully tuned to detect patients with Mucoviscidosis and place notifications within the patient chart of the patient data management system (PDMS) on intensive care units.

Building a Comprehensive Clinical Data Repository Using FHIR, LOINC and SNOMED

In 2018 the University Hospital of Giessen (UHG) moved its hospital information system from an in-house solution to commercial software. The introduction of MEONA and Synedra-AIM allowed for the successful migration of clinical documents. The large pool of structured clinical data has been addressed in a second step and is now consolidated in a HAPI-FHIR server and mapped to LOINC and SNOMED for semantic interoperability in multicenter research projects, especially the German Medical Informatics Initiative (MII) and the Medical Informatics in Research and Care in University Medicine (MIRACUM) consortium.

Patient Recruitment System for Clinical Trials: Mixed Methods Study About Requirements at Ten University Hospitals

BACKGROUND

Clinical trials are the gold standard for advancing medical knowledge and improving patient outcomes. For their success, an appropriately sized cohort is required. However, patient recruitment remains one of the most challenging aspects of clinical trials. Information technology (IT) support systems-for instance, patient recruitment systems-may help overcome existing challenges and improve recruitment rates, when customized to the user needs and environment.

OBJECTIVE

The goal of our study is to describe the status quo of patient recruitment processes and to identify user requirements for the development of a patient recruitment system.

METHODS

We conducted a web-based survey with 56 participants as well as semistructured interviews with 33 participants from 10 German university hospitals.

RESULTS

We here report the recruitment procedures and challenges of 10 university hospitals. The recruitment process was influenced by diverse factors such as the ward, use of software, and the study inclusion criteria. Overall, clinical staff seemed more involved in patient identification, while the research staff focused on screening tasks. Ad hoc and planned screenings were common. Identifying eligible patients was still associated with significant manual efforts. The recruitment staff used Microsoft Office suite because tailored software were not available. To implement such software, data from disparate sources will need to be made available. We discussed concrete technical challenges concerning patient recruitment systems, including requirements for features, data, infrastructure, and workflow integration, and we contributed to the support of developing a successful system.

CONCLUSIONS

Identifying eligible patients is still associated with significant manual efforts. To fully make use of the high potential of IT in patient recruitment, many technical and process challenges have to be solved first. We contribute and discuss concrete technical challenges for patient recruitment systems, including requirements for features, data, infrastructure, and workflow integration.

Prototypical Clinical Trial Registry Based on Fast Healthcare Interoperability Resources (FHIR): Design and Implementation Study

Background

Clinical trial registries increase transparency in medical research by making information and results of planned, ongoing, and completed studies publicly available. However, the registration of clinical trials remains a time-consuming manual task complicated by the fact that the same studies often need to be registered in different registries with different data entry requirements and interfaces.

Objective

This study investigates how Health Level 7 (HL7) Fast Healthcare Interoperability Resources (FHIR) may be used as a standardized format for exchanging and storing clinical trial records.

Methods

We designed and prototypically implemented an open-source central trial registry containing records from university hospitals, which are automatically exported and updated by local study management systems.

Results

We provided an architecture and implementation of a multisite clinical trials registry based on HL7 FHIR as a data storage and exchange format.

Conclusions

The results show that FHIR resources establish a harmonized view of study information from heterogeneous sources by enabling automated data exchange between trial centers and central study registries.

Design for a Modular Clinical Trial Recruitment Support System Based on FHIR and OMOP

The MIRACUM consortium is developing a Clinical Trials Recruitment Support System to support the data-driven recruitment of patients for clinical trials. The design of the prototype includes both open source solutions (OMOP CDM, Atlas) and open standards for interoperability (FHIR). The aim of the prototype is to create a patient screening list of potential participants for a clinical study. The paper shows the modular structure and functionality of the prototype building the foundation for the practical implementation of the CTRSS and, at the same time, demonstrating the use of open source solutions and standards for the development of clinical support systems.

Restenosis after coronary placement of various stent types

Coronary stent implantation is being performed in an increasing number of patients with a wide spectrum of clinical and lesion characteristics. A variety of stent designs are now available and continuous efforts are being made to improve the stent placement procedure. The objective of this study was to perform a comprehensive analysis of the relation between clinical, lesion, and procedural factors, and restenosis after intracoronary stenting in a large and unselected population of patients. A consecutive series of 4,510 patients with coronary stent placement was analyzed. Exclusion criteria were only a failed procedure and an adverse outcome within the first month after the intervention. Follow-up angiography was performed in 80% of patients at 6 months. Clinical, lesion, and procedural data from all 3,370 patients (4,229 stented lesions) with follow-up angiography were analyzed in a logistic regression model for restenosis (> or =50% diameter stenosis). Clinical factors contributed to the predictive power of the model much less than lesion and procedural factors. The strongest risk factor for restenosis was a small vessel size, with a 79% increase in the risk for a vessel of 2.7 mm versus a vessel of 3.4 mm in diameter. Stent design was the second strongest factor; the incidence of restenosis ranged from 20.0% to 50.3% depending on the stent type implanted. In conclusion, this study demonstrates the predominant role of lesion and procedural factors in determining the occurrence of restenosis after coronary stent placement. Among these factors, stent design appears to play a particularly important role in the hyperplastic response of the vessel wall.

Coronary microvascular reactivity to sympathetic stimulation in patients with idiopathic dilated cardiomyopathy

The objective of this study was to assess noninvasively the microvascular reactivity to sympathetic stimulation in patients with idiopathic dilated cardiomyopathy (IDC) and in healthy volunteers, who underwent cardiac catheterization for exclusion of coronary artery disease.

METHODS

Myocardial flow was quantified with 13N-ammonia PET and tracer kinetic modeling at rest and in response to cold pressor testing (CPT). Ten healthy volunteers (8 men, 2 women; mean age +/- SD, 50.7 +/- 15 y) and 10 matched patients (8 men, 2 women; mean age, 52.5 +/- 14 y) with IDC (mean left ventricular ejection fraction, 0.30 +/- 0.12) were included in the study.

RESULTS

Myocardial perfusion at rest was not significantly different between the groups. However, myocardial vascular resistance (MVR) was significantly lower in IDC patients at rest than in healthy volunteers. In response to CPT a significant decrease in MVR was found in healthy volunteers (1.9 +/- 0.4 to 1.5 +/- 0.4 mm Hg x 100 g/mL; 22% decrease) but not in IDC patients (1.5 +/- 0.4 to 1.4 +/- 0.3 mm Hg x 100 g/mL; 9% decrease). Consequently, the increase of the myocardial blood flow in response to CPT was significantly lower (P < 0.008) in IDC patients (56 +/- 17 to 66 +/- 18 mL/100g/min; 20% increase) compared with healthy volunteers (52 +/- 12 to 80 +/- 30 mL/100 g/min; 52% increase), whereas both showed comparable hemodynamic reactions.

CONCLUSION

The data indicate that CPT in combination with 13N PET imaging is a valuable noninvasive tool for assessment of coronary microvascular reaction to sympathetic stimulation in IDC patients. Lower coronary vascular resistance was found in IDC patients at rest compared with healthy volunteers, suggesting possible exhaustion of sympathetically induced dilation of the coronary microvasculature in IDC patients at rest. This mechanism may explain the impaired flow response to cold in IDC patients in the present study.

Effect of glycoprotein IIb/IIIa receptor blockade with abciximab on clinical and angiographic restenosis rate after the placement of coronary stents following acute myocardial infarction

OBJECTIVES

In the Intracoronary Stenting and Antithrombotic Regimen-2 trial (ISAR-2), we sought to investigate the effect of abciximab on angiographic and clinical restenosis after stenting following acute myocardial infarction (AMI). We also intended to assess the impact of abciximab on clinical outcome in this setting.

BACKGROUND

It is unclear whether abciximab reduces neointima formation after stenting. Such an effect may be particularly prominent in thrombus-containing lesions.

METHODS

Patients undergoing stenting within 48 h after onset of AMI were randomly assigned to receive either standard-dose heparin or abciximab plus reduced-dose heparin. Of 401 patients randomized, 366 without 30-day adverse events were eligible for six-month angiographic follow-up. Scheduled angiography was performed in 80% of these patients.

RESULTS

By 30 days, the composite clinical end point of death, reinfarction, and target lesion revascularization (TLR) was reached in 5.0% of the abciximab group and in 10.5% of the control group (p = 0.038). At one year, absolute reduction in the composite clinical end point by abciximab was still 5.7% but had lost its statistical significance. Our primary end point, late lumen loss, was 1.26+/-0.85 mm with abciximab and 1.21+/-0.74 mm with standard heparin (p = 0.61), and binary angiographic restenosis rates were 31.1% and 30.6%, respectively (p = 0.92).

CONCLUSIONS

In patients undergoing stenting following AMI, abciximab exerted beneficial effects by substantially reducing the 30-day rate of major adverse cardiac events. During one-year follow-up, there was no additional benefit from a reduction in TLR nor did abciximab reduce angiographic restenosis.

Early recovery of coronary flow reserve after stent implantation as assessed by positron emission tomography

OBJECTIVES

The aim of this study was to quantitatively evaluate myocardial flow reserve in patients early after coronary stent implantation using positron emission tomography.

BACKGROUND

Delayed restoration of coronary flow reserve after percutaneous transluminal coronary angioplasty (PTCA) has been observed using a variety of techniques. Altered distal vasoregulation as well as residual stenosis have been considered possible explanations for this phenomenon. Although the implantation of stents may influence some of these mechanisms, little data are available characterizing coronary flow reserve early after stent placement.

METHODS

In 14 patients 1.6 +/- 0.6 days after stenting, N-13-ammonia positron emission tomographic studies were performed at rest and during adenosine-induced vasodilation. Myocardial blood flow was quantified using a three-compartment model. Rest and stress flow data, as well as coronary flow reserve of stented vascular territories, were compared with that of remote areas.

RESULTS

The stenosis decreased from 72.1 +/- 7.3% to 3.7 +/- 6.7% after stent implantation. Coronary flow in the stented areas did not differ significantly from that in remote areas either at rest (76.1 +/- 18.5 and 75.7 +/- 17.7 ml/min/100 g, respectively), or during maximal vasodilation (205.5 +/- 59.9 and 179.4 +/- 47.4 ml/min/100 g, respectively). In addition, there was no significant difference in the calculated values of coronary reserve of these two regions (2.74 +/- 0.64 and 2.43 +/- 0.55, respectively).

CONCLUSIONS

The mechanical support of dilated arteries by a stent not only restores the macroscopic integrity of epicardial arteries, but also results, in contrast to conventional PTCA procedures, in early recovery of flow reserve.

Prognostic value of the modified american college of Cardiology/American heart association stenosis morphology classification for long-term angiographic and clinical outcome after coronary stent placement

Background-The modified American College of Cardiology/American Heart Association (ACC/AHA) lesion morphology criteria are predictive of early outcome after various coronary catheter interventions. Their potential prognostic value after stent implantation and, in particular, for restenosis and long-term clinical outcome has not been studied. We assessed the prognostic value of the modified ACC/AHA criteria for the long-term angiographic and clinical outcome of patients after coronary stenting. Methods and Results-This study includes 2944 consecutive patients with symptomatic coronary artery disease treated with coronary stent placement. Modified ACC/AHA lesion morphology criteria were used to qualitatively assess the angiograms; type A and B1 lesions were categorized as simple, and type B2 and C lesions were designated complex. Primary end points were angiographic restenosis and 1-year event-free survival. Restenosis rate was 33.2% in complex lesions and 24.9% in simple lesions (P<0.001). It was 21. 7% for type A, 26.3% for type B1, 33.7% for type B2, and 32.6% for type C lesions. One-year event-free survival was 75.6% for patients with complex lesions and 81.1% for patients with simple lesions (P<0. 001). It was 85.2% for patients with type A, 79.4% for type B1, 75. 9% for type B2, and 75.2% type C lesions. The higher risk for restenosis and an adverse outcome associated with complex lesions was also maintained after multivariate adjustment for other clinical and angiographic characteristics. Conclusions-The modified ACC/AHA lesion morphology scheme has significant prognostic value for the outcome of patients after coronary stent placement. Lesion morphology is able to influence the restenosis process and thus the entire 1-year clinical course of these patients.

Influence of balloon pressure during stent placement in native coronary arteries on early and late angiographic and clinical outcome: A randomized evaluation of high-pressure inflation

BACKGROUND

High-pressure dilatation is considered a better stent placement strategy, but this has not yet been proved by appropriately designed studies. The objective of this randomized trial was to assess the role of high-pressure dilatation in the early and late outcome of patients undergoing coronary stent placement.

METHODS AND RESULTS

Consecutive patients with coronary stent placement were randomly assigned to high- (15 to 20 atm, 468 patients) or low- (8 to 13 atm, 466 patients) balloon-pressure dilatation. The primary end point of the study was the event-free survival at 1 year. Secondary end points were the incidence of stent thrombosis at 30 days and angiographic restenosis (>/=50% diameter stenosis) at 6 months. The incidence of stent thrombosis was 1.7% in the high-pressure and 1.9% in the low-pressure group (relative risk 0.89; 95% CI 0.30 to 2.56). During the first 30 days, although there was no significant difference in the incidence of Q-wave myocardial infarction, the incidence of non-Q-wave infarction was 6.4% in the high-pressure and 3.4% in the low-pressure group (relative risk 1. 87; 95% CI 1.02 to 3.42). The restenosis rate was 30.4% in the high-pressure and 31.4% in the low-pressure group (relative risk 0. 97; 95% CI 0.75 to 1.26). Event-free survival at 1 year was not significantly different between the groups, with 78.8% in high-pressure patients and 75.5% in patients assigned to low-pressure dilatation (hazard ratio 0.85; 95% CI 0.65 to 1.11).

CONCLUSIONS

The systematic use of high-balloon-pressure inflation (15 to 20 atm) during coronary stent placement is not associated with any significant influence on the 1-year outcome of patients undergoing this intervention.

Effect of glycoprotein IIb/IIIa receptor blockade on recovery of coronary flow and left ventricular function after the placement of coronary-artery stents in acute myocardial infarction

BACKGROUND

Apart from its established effects on vessel patency after percutaneous coronary revascularization, glycoprotein IIb/IIIa receptor blockade by abciximab may improve myocardial perfusion by inhibition of the interaction of platelets and platelet aggregates with the microvasculature. We investigated the effect of abciximab with stent placement in acute myocardial infarction.

METHODS AND RESULTS

In a prospective randomized trial, patients undergoing stenting in acute myocardial infarction within 48 hours after onset of symptoms were randomly assigned to receive either standard-dose heparin or abciximab plus low-dose heparin. Immediately after the procedure and at 14-day angiographic follow-up, we assessed flow velocity in the recanalized vessel with the Doppler wire and regional wall motion by the centerline method. End points were changes in papaverine-induced peak flow velocities and in wall motion indices. We assigned 98 patients to standard heparin and 102 to abciximab. We obtained 152 paired flow measurements and 151 paired left ventricular function studies. Residual stenoses of the treated lesions did not differ between the 2 groups. Improvement of peak flow velocity (mean [95% CI]: 18.1 cm/s [13.6 to 22.6 cm/s], n=80, versus 10.4 cm/s [5.4 to 15.4 cm/s], n=72, P=0.024) and wall motion index (0.44 SD/chord [0.29 to 0.59 SD/chord], n=79 versus 0. 15 SD/chord [0.00 to 0.30 SD/chord], n=72, P=0.007) was significantly greater in patients assigned to abciximab than in those on heparin alone. At follow-up, the abciximab group had a higher global left ventricular ejection fraction than the heparin group (62% [59% to 65%] versus 56% [53% to 59%], P=0.003).

CONCLUSIONS

Abciximab had important effects beyond the maintenance of large-vessel patency. It improved the recovery of microvascular perfusion and concomitantly enhanced the recovery of contractile function in the area at risk.

Myocardial perfusion scintigraphy to evaluate patients after coronary stent implantation

Coronary stent implantation is an increasingly accepted revascularization method. The 20%-30% restenosis rate during the first 6 mo requires a close follow-up of the patients. Since there is very little data available defining the role of perfusion scintigraphy in the management of this population, the aim of this study was to assess the diagnostic performance of stress myocardial perfusion imaging for detecting restenosis in patients after coronary stent implantation.

METHODS

In 82 patients, 93 rest or stress SPECT studies were performed using 201Tl and 99mTc-hexakis-2-methoxyisobutyl isonitrile to evaluate 99 vascular territories with implanted coronary stents. The average interval between the stent implantation and the scintigraphic study was 210.5 +/- 129.6 days. The scintiscans were visually evaluated. A stress-induced perfusion defect with reversibility at rest was used as the criterion for stent restenosis.

RESULTS

Coronary angiography revealed a stenosis of > 50% diameter in the region of the stent in 19 arteries, while in 80 arteries there was no evidence of restenosis angiographically. With perfusion scintigraphy, 15/19 vascular territories with restenosed stents showed stress-induced perfusion abnormalities (sensitivity = 79%), while 62/80 territories without restenosis did not (specificity = 78%). In territories without a myocardial infarction (n = 48), sensitivity and specificity values were 8/8 (100%) and 36/44 (82%), and in territories with a myocardial infarction (n = 47) 7/11 (64%) and 26/36 (72%), respectively. Side branch stenosis was fairly frequent in patients without stent restenosis but with a reversible perfusion pattern on their scintiscan (8/18); however, these stenoses were induced infrequently by the stents (3 cases).

CONCLUSION

Using the criterion of defect reversibility, stress perfusion SPECT can accurately detect restenoses of coronary artery stents. This method is most accurate for evaluating patients without a previous myocardial infarction in the stented vascular territory.

Restenosis rate after intravascular ultrasound-guided coronary stent implantation

This study was designed to test the hypothesis that patients fulfilling intravascular ultrasound (IVUS) criteria for optimal coronary stent implantation show a reduction in the restenosis rate at 6 months. IVUS guidance for stent dilation may be associated with facilitated stent implantation and an increased acute luminal gain, but it has not yet been determined, whether and to what extent this procedure is associated with a reduction in the restenosis rate. IVUS-guided optimization of Palmaz-Schatz stent placement was performed in 125 consecutive patients, 64 of whom fulfilled IVUS-criteria for optimal stent placement. Another 125 patients served as the non-IVUS control group. In 107 patients (86%) of the non-IVUS control group and 105 patients (84%) of the IVUS group, angiographic follow-up was performed. The IVUS group of patients revealed a significantly lower restenosis rate of 20.9% as compared with 29.9% in the control group (P = 0.033). Patients that met IVUS criteria for optimal stent placement had a larger minimal lumen diameter immediately after stent implantation (3.13 +/- 0.44 vs. 2.95 +/- 0.47 mm; P = 0.045) and at 6-month follow-up (2.23 +/- 0.78 vs. 1.87 +/- 0.76 mm; P = 0.019) as well as a significantly lower restenosis rate (13.5% vs. 28.3%; P = 0.038) as compared with patients that did not fulfil these criteria. Our data suggest that patients fulfilling IVUS criteria for optimal stent placement demonstrate a reduced risk for the development of restenosis. Thus, IVUS investigation identifies factors predictive of restenosis after coronary stent placement.

Recovery of myocardial perfusion in acute myocardial infarction after successful balloon angioplasty and stent placement in the infarct-related coronary artery

OBJECTIVES

This study sought to investigate changes in myocardial perfusion after direct percutaneous transluminal coronary angioplasty (PTCA) in acute myocardial infarction (MI).

BACKGROUND

After initially successful recanalization of the infarct-related artery, coronary perfusion may deteriorate as a result of reocclusion, distal embolization of platelet aggregates formed at the dilated plaque or microvascular reperfusion injury. This change could offset the benefit from early intervention.

METHODS

The study included 19 patients in whom the infarct-related artery was successfully recanalized by PTCA with Palmaz-Schatz stent placement within 24 h after the onset of pain. Basal and papaverine-induced coronary blood flow were assessed by Doppler flow velocity measurements and quantitative coronary angiography. In addition, basal and adenosine-induced myocardial blood flow were measured by nitrogen-13 ammonia positron emission tomography (PET).

RESULTS

Immediately after completion of the intervention, the average coronary flow reserve (CR) in the recanalized vessel was 1.56 +/- 0.51; it increased to 2.04 +/- 0.65 at 1 h (p = 0.013) and to 2.66 +/- 0.72 at 2 weeks after reperfusion (p = 0.008, n = 16). PET studies in 12 patients revealed that perfusion defect size and CR in the infarct region (2.19 +/- 0.89 vs. 2.33 +/- 0.86) did not change significantly between day 2 after recanalization and 2 weeks. However, we found significant (p < 0.03) increases in basal (by 26%) and adenosine-induced (by 40%) blood flow in the infarct region.

CONCLUSIONS

Despite the persistence of a perfusion defect after successful recanalization of the occluded artery in acute MI, CR of the infarct region improves in most patients within 1 h and further improves within 2 weeks.

Comparison of angiography and intravascular ultrasound for the assessment of lumen size after coronary stent placement: impact of dilation pressures

This study was designed to assess the extent of potential discrepancies between intravascular ultrasound (IVUS) and quantitative coronary angiography (QCA) measurement of intrastent minimal luminal diameter and to evaluate the impact of dilation pressures and the balloon:artery ratio on the assessment of the minimal lumen diameter (MLD) by these imaging modalities. IVUS is recommended as an adjunct to angiography to assess stent expansion; however, the extent of potential discrepancies between the two imaging modalities is not well defined. Included were 225 patients in whom coronary Palmaz-Schatz stents were successfully placed after PTCA. IVUS and QCA were performed at the end of the intervention. We compared the MLD assessed by QCA and IVUS in the instent and reference site. The MLD assessed by IVUS and QCA were 2.68 +/- 0.41 mm and 3.08 +/- 0.47 mm (P < 0.001), respectively, at the tightest intrastent site and 3.19 +/- 0.50 mm and 3.17 +/- 0.52 ns at the reference site. There was a correlation between the dilation pressure and the difference between QCA- and IVUS-based intrastent MLD measurement (y = -0.05x + 1.11; r = -0.53; P < 0.0001). At low dilation pressures, a significant difference between the image modalities was found, but after high dilation pressures no discrepancies were detected. No relation was found with the balloon:artery ratio. These data provide clear evidence that in the case of low-pressure dilation, the exclusive reliance on data obtained by QCA will not yield sufficiently accurate information on intrastent MLD, whereas after high dilation pressure, the differences between the imaging modalities are minimized.

Antiplatelet effect of ticlopidine after coronary stenting

OBJECTIVES

This study sought to investigate the contribution of ticlopidine to the inhibition of platelet activation after coronary stent placement.

BACKGROUND

After coronary stenting, antiplatelet therapy with aspirin and ticlopidine improves stent patency compared with anticoagulation. However, the specific role of ticlopidine has not been elucidated.

METHODS

After successful coronary stent placement, we randomized 22 patients to receive ticlopidine and aspirin (ticlopidine group) and 25 to receive aspirin alone (aspirin group). Surface expression on platelets of the activated fibrinogen receptor and of P-selectin was assessed by flow cytometry.

RESULTS

In the aspirin group the percent of platelets with activated fibrinogen receptors increased between days 1 and 5 (p = 0.001), whereas there were no substantial changes in the ticlopidine group. The percent of P-selectin-positive platelets did not change significantly in the aspirin group but decreased in the ticlopidine group (p = 0.019). At day 5 after the intervention, the percent of platelets with activated fibrinogen receptors in the ticlopidine group was significantly lower (median [interquartile range]: 8.5 [3.1 to 17.8] vs. 18.1 [8.5 to 35.5], p = 0.025), and there was a trend to fewer P-selectin-positive platelets than in the aspirin group (5.8 [3.4 to 9.5] vs. 8.8 [4.0 to 15.8], p = 0.073).

CONCLUSIONS

Combined antiplatelet therapy with ticlopidine plus aspirin is superior to treatment with aspirin alone in suppressing platelet activation after coronary stenting.

Coronary stent placement in patients with acute myocardial infarction: comparison of clinical and angiographic outcome after randomization to antiplatelet or anticoagulant therapy

OBJECTIVES

The Intracoronary Stenting and Antithrombotic Regimen (ISAR) trial is a randomized comparison of combined antiplatelet with anticoagulant therapy after coronary Palmaz-Schatz stent placement. The objective of this study was to compare early and late clinical and angiographic outcome in a subgroup of patients with stent placement for acute myocardial infarction.

BACKGROUND

Stenting has become a treatment option for acute myocardial infarction, but it is not known which antithrombotic regimen is more adequate after stent implantation.

METHODS

One hundred twenty-three patients with successful stenting after acute myocardial infarction were randomized to receive aspirin plus ticlopidine (n = 61) or intense anticoagulant therapy (n = 62). Six-month repeat angiography was performed in 101 (86.3%) eligible patients.

RESULTS

During the first 30 days after stenting, patients with antiplatelet therapy had a significantly lower clinical event rate (3.3% vs. 21.0%, p = 0.005) and stent vessel occlusion rate (0% vs. 9.7%, p = 0.03) and a trend to fewer cardiac events (1.6% vs. 9.7%, p = 0.12). After 6 months, the survival rate free of recurrent myocardial infarction was higher in patients with antiplatelet therapy (100% vs. 90.3%, p = 0.03), and the rate of stent vessel occlusion was lower (1.6% vs. 14.5%, p = 0.02). Both groups had comparable restenosis rates (26.5% vs. 26.9%, p = 0.87).

CONCLUSIONS

This study demonstrates that combined antiplatelet therapy after stent placement in patients with acute myocardial infarction is associated with an overall better clinical and angiographic outcome than anticoagulant therapy.

Intravascular ultrasound-guided emergency coronary Palmaz-Schatz stent placement without post-procedural systemic anticoagulation

OBJECTIVE

To test the efficacy of intravascular ultrasound (IVUS)-guided stent placement and to determine the clinical outcome during the first 30 days in those patients who were treated with antiplatelet therapy rather than anticoagulants because they met the IVUS criteria for optimal stent placement.

DESIGN

Prospective observational study.

PATIENTS

126 patients with successful, non-elective Palmaz-Schatz stent placement.

INTERVENTIONS

IVUS was performed to assess the attachment of stent struts, the coverage of the dissection, and the intrastent minimal lumen area.

MAIN OUTCOME MEASURES

Intrastent lumen area, clinical outcome during the first 30 days.

RESULTS

In all patients IVUS showed complete apposition and coverage of the dissection. In 23 patients (18%) the IVUS lumen area criterion was achieved. In 75 patients, further balloon dilatation was performed and in 41 IVUS criteria were finally fulfilled. The minimal intrastent lumen area increased from a mean (SD) of 6.81 (1.15) mm2 to 9.56 (2.61) mm2 (P < or = 0.01) between the first and final IVUS investigations. 64 patients (51%) who met the IVUS criteria were treated with aspirin (100 mg) and ticlopidine (250 mg) twice a day. During the first 30 days none of the following events occurred: death, myocardial infarction, repeat intervention, aortocoronary bypass surgery, and subacute stent thrombosis.

CONCLUSION

The additional information provided by IVUS examination helped the operator to decide whether further dilatation was needed after a coronary stent had been placed. For patients who met the IVUS criteria for optimal stent placement, antiplatelet therapy was associated with an excellent clinical outcome during the first 30 days.

A randomized comparison of antiplatelet and anticoagulant therapy after the placement of coronary-artery stents

BACKGROUND

The clinical benefit of coronary-artery stenting performed in conjunction with coronary angioplasty is limited by the risk of thrombotic occlusion of the stent as well as hemorrhagic and vascular complications of intensive anticoagulation. We compared antiplatelet therapy with conventional anticoagulant therapy with respect to clinical outcomes 30 days after coronary-artery stenting.

METHODS

After successful placement of Palmaz-Schatz coronary-artery stents, 257 patients were randomly assigned to receive antiplatelet therapy (ticlopidine plus aspirin) and 260 to receive anticoagulant therapy (intravenous heparin, phenprocoumon, and aspirin). The primary cardiac end point was a composite measure reflecting death from cardiac causes or the occurrence of myocardial infarction, aortocoronary bypass surgery, or repeat angioplasty. The primary noncardiac end point comprised death from noncardiac causes, cerebrovascular accident, severe hemorrhage, and peripheral vascular events.

RESULTS

Of the patients assigned to antiplatelet therapy, 1.6 percent reached a primary cardiac end point, as did 6.2 percent of those assigned to anticoagulant therapy (relative risk, 0.25; 95 percent confidence interval, 0.06 to 0.77). With antiplatelet therapy, there was an 82 percent lower risk of myocardial infarction than in the anticoagulant-therapy group, and a 78 percent lower need for repeat interventions. Occlusion of the stented vessel occurred in 0.8 percent of the antiplatelet-therapy group and in 5.4 percent of the anticoagulant-therapy group (relative risk, 0.14; 95 percent confidence interval, 0.02 to 0.62). A primary noncardiac end point was reached by 1.2 percent of the antiplatelet-therapy group and 12.3 percent of the anticoagulant-therapy group (relative risk, 0.09; 95 percent confidence interval, 0.02 to 0.31). Hemorrhagic complications occurred only in the anticoagulant-therapy group (in 6.5 percent). An 87 percent reduction in the risk of peripheral vascular events was observed with antiplatelet therapy.

CONCLUSIONS

As compared with conventional anticoagulant therapy, combined antiplatelet therapy after the placement of coronary-artery stents reduces the incidence of both cardiac events and hemorrhagic and vascular complications.

Correlation between LDA and ultrasound heart catheter measurements in a stenosed arterial model

Ultrasound heart catheters are used to measure the velocity in coronary arteries. However, the act of introducing a catheter into the vessel disturbs the very flow being measured. We used laser Doppler anemometry to measure the velocity distribution in an axially symmetric model, both with and without a catheter inserted. The catheter reduced the center-line velocity by as much as 60 percent at a distance of 2 mm downstream from the catheter, and by as much as 25 percent at a distance of 10 mm. This means the velocity measured with an ultrasound catheter does not show the maximum velocity of the undisturbed flow in the tube center. In the constriction, however, the measured velocities with the LDA and ultrasound catheter are almost the same. Thus, catheter measurements in the stenosis achieve accurate results. The velocity profile in the stenosed areas is flattened over nearly the whole cross section. The velocity is extremely reduced only close to the wall. The measurements outside of the stenosis lead to large differences which need to be studied carefully in the future. The disturbed flow finally disappeared 15 mm downstream of the catheter. The measurements were done at steady flow using a glycerine water solution with a dynamic viscosity of 4.35 mPas. In future studies, these experiments will be repeated for pulsatile flow conditions using non-Newtonian blood-like fluids.

Four-year experience with Palmaz-Schatz stenting in coronary angioplasty complicated by dissection with threatened or present vessel closure

BACKGROUND

Abrupt vessel closure after percutaneous transluminal coronary angioplasty (PTCA) is associated with major adverse events. Different surgical and nonsurgical approaches have been advocated to treat or prevent this complication. This study summarizes our 4-year experience with Palmaz-Schatz stenting for the management of 339 patients with present or threatened occlusion after PTCA.

METHODS AND RESULTS

Stent implantation was attempted in a total of 339 and 4959 patients with PTCA during the study period and was successful in 327 (96.5%). During the follow-up, events like death, myocardial infarction, need for revascularization (bypass surgery and repeat in-stent angioplasty), and major vascular complications were recorded. Angiographic follow-up at 6 months was performed in 89.3% of the eligible patients. As part of an initial policy, stenting was intended as a bridge to nonemergency bypass surgery in 26 patients. In 301 patients for whom stenting was intended as permanent treatment, early clinical course (first 4 weeks) was characterized by a 1.3% cardiac mortality and a 4.0% nonfatal myocardial infarction rate; bypass surgery was necessary in 1%, and 6.3% required early repeat PTCA. Surgical repair for peripheral vascular complications was required in 5.6%, and major bleeding events were encountered in 9%. The incidence of subacute stent closure was 6.9%, with subsequent recanalization successful in 86%; subacute stent closure was predicted by presence of vessel occlusion before stenting and localization of the stent in a vessel other than the right coronary artery. Survival rate at 2 years was 95.4%, survival without myocardial infarction was 91.1%, and event-free survival was 70.7%. Survival at 2 years was lower for patients with stents in bypass vein grafts and with myocardial infarction after stenting. Six-month control angiography revealed a restenosis rate of 29.6%.

CONCLUSIONS

Patients with present or threatened occlusion after PTCA may benefit from Palmaz-Schatz stenting. It is associated with a low mortality and myocardial infarction rate and with a long-term event-free rate comparable to that of uncomplicated PTCA.

Ultrasound guidance of Palmaz-Schatz intracoronary stenting with a combined intravascular ultrasound balloon catheter

BACKGROUND

Coronary stenting in conjunction with coronary angioplasty is a valuable tool for treatment of severe coronary dissection and is effective in reducing the frequency of restenoses. Evidence is increasing that the lumen gain within the stent is negatively correlated with the rate of subacute closures and restenoses. Since the assessment of radiolucent coronary stents and complex lumen morphologies by angiography is limited, we hypothesized that the use of a balloon catheter with integrated intravascular ultrasound (IVUS) facility for stent deployment and guidance of its expansion could improve the acute lumen gain without relevant procedural prolongation.

METHODS AND RESULTS

Deployment of a single Palmaz-Schatz coronary stent with the combined imaging balloon catheter alone was successful in 18 of 20 patients eligible for this study. Corresponding measurements of minimal lumen diameter (MLD) by angiography and IVUS could be performed in 16 patients, revealing a close correlation between the two methods within the reference segments (3.10 +/- 0.38 and 3.08 +/- 0.43 mm, r = .79). Despite an adequate angiographic result in most patients after stent deployment, IVUS showed smaller MLD within the stented segment (2.15 +/- 0.23 mm) compared with angiography (2.63 +/- 0.26 mm, P < .0001) with a poor correlation (r = .27). To achieve IVUS criteria for optimal stent expansion (ratio of 0.9 between IVUS-assessed cross-sectional area of stent and reference segment), an average of three additional balloon inflations with higher pressure and/or a larger balloon diameter were performed without adverse effects in 15 of 16 patients who initially did not fulfill these criteria. This resulted in a significant increase in stent MLD to 2.63 +/- 0.27 mm (IVUS, P < .0001 versus initial MLD) and 2.89 +/- 0.32 mm (angiography, P < .0002 versus initial MLD) and a better correlation between the two methods (r = .60). The IVUS guidance led to a 40 +/- 15% increase of the minimal stent cross-sectional area with an additional time consumption of 21 minutes on average.

CONCLUSIONS

This study demonstrates the application of a combined imaging balloon catheter for delivery and ultrasound-guided expansion of Palmaz-Schatz coronary stents. IVUS offered a comprehensive insight into the stented coronary segments, revealing a substantial overestimation of stent dimensions by angiography. IVUS guidance led to a significant improvement of stent expansion. This additional lumen gain, which was not discernible by angiography in most patients, might result in a reduction of subacute stent thromboses as well as restenoses.

Intravascular ultrasound assessment of the balloon-expandable Palmaz-Schatz coronary stent

BACKGROUND

Coronary stenting is an effective method for the treatment of acute coronary dissection and restenosis. In the comprehensive assessment of restenosis and of the complex interaction between coronary stent and vessel wall, coronary arteriography has significant limitations. Intravascular ultrasound as a high-resolution tomographic imaging method is a promising tool for resolving these limitations.

METHODS

A 3.5, 5.0 or 5.5F, 20 MHz multi-element ultrasound catheter was used in 27 patients who had received a Palmaz-Schatz coronary stent for the treatment of symptomatic coronary dissection. Intravascular ultrasound study was performed during routine follow-up arteriography at 3-10 months in all 27 patients and had also been performed in four patients during stent deployment. Four patients with restenosis within the stent were re-investigated 3 months later after repeat angioplasty.

RESULTS

Complete analysis of the stented coronary segment could be performed in 34 out of 35 studies (97%); no adverse effects occurred. The three layer appearance of the vessel wall was not discernible in most patients because of a complex and often eccentric lesion surrounding the stent resulting in an asymmetrical arrangement of stent filaments. The beginning and the end of the stent, the central strut, and the overlap of a double stent could be well assessed. Luminal diameters ranged from 1.95 to 4.15 mm and cross-sectional areas from 3.83 to 10.85 mm2. Correlations with quantitative arteriography revealed r-values of 0.58 for diameter and 0.59 for area. A stent-covering layer, indicative of neointima, was clearly visible in all patients during follow-up arteriography with a diameter of 0.10-0.95 mm (mean 0.25 +/- 0.15 mm), which resulted in a reduction of 2-63% in the cross-sectional area of the vessel. This layer did not exceed a thickness of 0.4 mm in asymptomatic patients.

CONCLUSIONS

This study demonstrates the safe and feasible application of intravascular ultrasound in patients with stented coronary lesions. Differences between the angiographic and ultrasonic measurements are presumably the result of the limitations of radiography in complex and eccentric lesions. Intracoronary ultrasound provides a unique comprehensive assessment of stent expansion, neointimal proliferation, and restenosis mechanisms. Thus, intravascular ultrasound may also have implications regarding the indication for, and optimal deployment of, intracoronary stents.

Functional changes in left ventricular hypertrophy: diagnosis of impaired diastolic function in patients with hypertension

Left ventricular hypertrophy is usually associated with impaired left ventricular diastolic function which can be characterised by an altered pressure volume relationship. Since diastolic flow velocities are closely related to the difference in pressure between the left atrium and left ventricle, parameters of diastolic function can be determined by Doppler echocardiography. However, the pressure difference is additionally influenced by factors which have no relation to left ventricular diastolic function. These include preload, afterload, inotropy, heart rate and left ventricular systolic function. Despite these limitations, Doppler echocardiography is a valuable tool to diagnose therapeutic effects on diastolic function in patients with left ventricular hypertrophy.

[Intravascular ultrasound (IVUS): the assessment of tumor infiltration into the vascular wall]

The demonstration or exclusion of tumour infiltration into a vessel wall is made possible by IVUS. This was performed 25 times in 23 patients using a 20 MHz probe where there was suspicion of tumour infiltration on the basis of CT, MRI or angiography. IVUS proved very suitable for clarifying the situation, making direct intravascular evaluation of the affected vessel possible. In 10 cases where surgery was performed, the demonstration or exclusion of tumour infiltration into a vein was confirmed operatively in every case. Further experience is necessary before the value of the method for diagnosing early arterial infiltration can be judged.

Global and regional ventricular function following intracoronary application of papaverine

Intracoronary injection of papaverine is used to determine coronary flow reserve in patients. The present study was to investigate the effect of papaverine on the performance of myocardium with reduced flow reserve. In nine anaesthetized open-chest dogs a bypass from the aorta to the left circumflex coronary artery (LCX) was established. Left ventricular end-diastolic and aortic pressure, dP/dt, stroke volume, LCX blood flow, and ECG were monitored. The performance of a segment of subendocardial wall supplied by the LCX was assessed by sonomicrometry. Peak reactive hyperaemia after 15s bypass occlusion was 1.44 +/- 0.09 times the baseline flow (41 ml/min), indicating reduced coronary flow reserve. Papaverine was injected into the bypass (0.3, 0.6, 1.2, 2.5, 5.0 mg/ml, 1 ml in 15s). The maximum LCX flow following PAPA 0.3 mg was comparable to peak reactive hyperaemia, but 10-15% higher after injection of 0.6-5.0 mg papaverine. Systolic shortening of the myocardium (control: 17.5% of end-diastolic length) became reduced in a dose-dependent fashion (5-25%) for about 1 min following papaverine injection. Stroke volume (control: 0.94 +/- 0.12 ml/kg) was reduced by about 8%, left ventricular end-diastolic pressure (control: 6.2 +/- 0.8 mmHg) increased by 15%, and dP/dtmin (control: 1850 +/- 150 mmHg/s) was curtailed by 15-25%. The ECG showed a transient T inversion and S-T depression following papaverine administration and in one experiment ventricular fibrillation occurred after the injection of 2.5 mg papaverine. The observed effects of intracoronary papaverine are consistent with the theory of transient subendocardial ischaemia arising from a redistribution of blood flow from the subendocardial to the subepicardial layers, because of greater vasodilatory capacity in the latter than in the former.

[Comparison of the effect of a selective and a nonselective beta receptor blocker on the ischemic ST segment, lung function and stress-induced decrease in blood glucose]

This study was designed to compare the antihypertensive and anti-ischemic effects of the newly developed cardioselective beta-blocking agent, betaxolol, with the non-selective agent, nadolol, both of which have hydrophilic long acting properties, over a period of 48 hours. Additionally, the study was intended to determine whether betaxolol exerts a lesser influence on pulmonary function and whether beta-1- and beta-2-adrenergic blocking agents also induce a decrease in blood glucose levels during standard bicycle ergometry for three to nine minutes, similar to that reported in association with exercise of longer duration and, if so, whether this effect can be circumvented by the use of a selective agent. Ten patients with angiographically documented CAD, stable exercise angina pectoris and reproducible ST-segment depression of at least 1 mm received on day 1, in a single blind fashion, one tablet of placebo, on day 2 and day 7, in a double-blind, randomized and cross-over fashion, 20 mg betaxolol or 80 mg nadolol, respectively. Bicycle ergometry was performed before, four, 24 and 48 hours after drug with fixed work loads, blood glucose determination before and after ergometry four hours after drug and airway resistance and maximal ventilatory capacity studies were carried out five hours after drug administration. As compared with placebo, betaxolol and nadolol led to reductions of ST-segment depression of 65% (p less than 0.01) and 74% (p less than 0.005) at four hours, of 53% (p less than 0.025) and 56% (p less than 0.01) at 24 hours and 41% (p less than 0.05) and 44% (p less than 0.05) at 48 hours.(ABSTRACT TRUNCATED AT 250 WORDS)

[High-dose transdermal nitroglycerin therapy: loss of effect within 24 hours?]

Within a relatively short period of time, nitroglycerin patches have come into widespread use for treatment of coronary artery disease in the absence of sufficient clinical data in support of their efficacy. Presently, there is still considerable controversy regarding the extent and duration of action as well as the dosage requirements. Accordingly, a study was carried out in six patients with angiographically-documented coronary artery disease, stable exercise-induced angina pectoris and reproducible ST-segment depression to analyze the effects of nitroglycerin patches, formulated to deliver 5 mg, 10 mg, 20 mg as well as 30 mg per 24 hours, respectively, on the extent of ST-segment depression. In a further study, the extent and duration of antianginal and anti-ischemic effects of nitroglycerin patches delivering 30 mg/24 hours were investigated in ten patients according to a randomized, double-blind, crossover placebo-controlled protocol. In seven of these patients, testing was again performed at 2.5 hours after repeated application (second application at 24 hours) (Figure 1). Nitroglycerin patches delivering 5 mg, 10 mg, 20 mg as well as 30 mg/24 hours, respectively, led to significant reductions in ST-segment depression at 2.5 hours of 59% (range 25 to 100%; p less than 0.025), 63% (0 to 100%, p less than 0.01), 77% (50 to 100%, p less than 0.001) as well as 82% (50 to 100%, p less than 0.005) as compared with control values (Figure 2).(ABSTRACT TRUNCATED AT 250 WORDS)

[Long-term therapy of stress angina pectoris by a single daily administration of 120 mg isosorbide dinitrate in retard form. Comparison of monotherapy and combination therapy with atenolol and nifedipine]

This study was undertaken to determine whether an effective antianginal treatment without tolerance development can be carried out with intermittent nitrate administration on a regimen with a single daily dose of 120 mg isosorbide dinitrate (ISDN) in sustained-release form (SR), as well as whether the concomitant administration of 100 mg atenolol or 100 mg atenolol and 20 mg nifedipine renders an additive antiischemic effect. In two independently performed investigations, the duration of action of a single dose of 120 mg ISDN SR was assessed after its initial administration in addition to the anti-ischemic effect during long-term treatment, each according to a randomized, double-blind, crossover, placebo-controlled protocol in a total of 15 patients with angiographically-documented coronary artery disease, stable angina pectoris and reproducible ST-segment depression during exercise. The test phases of four weeks each were separated by one week placebo phases. After completion of the study, for a further eight weeks, 120 mg ISDN SR was given together with 100 mg atenolol in the morning. Exercise testing was carried out after four weeks of treatment in a control period before and at two hours after administration of 120 mg ISDN SR with 100 mg atenolol as well as after another four weeks in a control period before and after concomitant administration of 120 mg ISDN SR, 100 mg atenolol and 20 mg nifedipine in sustained release form.(ABSTRACT TRUNCATED AT 250 WORDS)

Über die Bedeutung der fibrinolytischen Aktivität der Lunge unter dem Aspekt des akuten Atemnotsyndroms

In tierexperimentellen Studien wurde histochemisch untersucht, inwieweit Pharmaka, die in der Gynäkologie bei Frühgeburtsgefahr prophylaktisch gegen die Entstehung eines akuten Atemnotsyndroms verwendet werden, einen Einfluß auf die fibrinolytische Aktivität der Lunge haben. Hierbei wurde nach Gabe von Betamethason eine Abnahme der gewebeständigen Fibrinolyse und eine Zunahme von Plasmininhibitoren in maternalem und fetalem Lungengewebe der Ratte gefunden, was nach Gabe von Ambroxol nicht der Fall war. Daraus ergibt sich im Hinblick auf eine nicht iatrogen verminderte fibrinolytische Aktivität der Frühgeborenenlunge ein Vorteil von Ambroxol.

In einer weiteren Untersuchungsreihe wurde geprüft, welchen Einfluß Aprotinin auf die gewebeständige Fi im Rahmen des traumatischen Schockgeschehens hat. Bei narkotisierten Ratten mit bilateraler Oberschenkelfraktur blieb nach 20000 KIE Aprotinin pro kg KG die fibrinolytische Aktivität des Lungengewebes erhalten, was für den Kliniker zeigt, daß im Falle einer sekundären Hyperfibrinolyse beim Schockpatienten keine Kontraindikation für Aprotinin besteht. Synthetische Fibrinolysehemmkörper dagegen, wie z. B. Tranexamsäure-Derivate, interferieren mit der Wirkung gewebeständiger Plasminogenaktivatoren und bewirken u. U. die Bildung von lyseresistenten Gerinnseln. Diese Substanzen dürfen deshalb bei keinem Zustand mit vermehrter Fibrinbildung gegeben werden.

[Antihypertensive and anti-ischemic effect of nitrendipine. Double-blind, randomized, crossover and placebo controlled acute study]

Nitrendipine is a newly-developed calcium channel blocker derived from the dehydropyridine series which, according to experimental studies, affects marked dilation of the peripheral and coronary vessels. As compared with the parent compound nifedipine, nitrendipine exhibits a clearly more prolonged elimination half-time. This study was designed to evaluate the antihypertensive efficacy, in particular, with respect to the duration of action as well as the anti-ischemic effectiveness with a protocol encompassing as many factors as possible. In 13 patients with angiographically-documented coronary artery disease and elevated blood pressure at rest and/or during exercise, on two days separated by a three-day washout period, we investigated the effects of 20 mg nitrendipine, as compared with placebo, in a double-blind, randomized, crossover study. The systolic and diastolic arterial blood pressure as well as the heart rate were recorded prior to, at two, five, eight and twelve hours after medication and the blood pressure only at 24 hours. Blood pressure and heart rate were assessed during active standing at two hours, passive tilt at 2 1/2 hours and, together with analysis of the ST segments, before and during semisupine bicycle ergometry performed at three hours after tablet administration.(ABSTRACT TRUNCATED AT 250 WORDS)

[Anti-ischemic effect of 8 mg molsidomin in retard form]

Studies of the efficacy of molsidomine, previously performed on our service, demonstrated that a clear antianginal effect in the longterm treatment of angina pectoris could only be achieved with a regimen of the standard 2 mg dose when given six times daily. Consequently, since a mode of administration with a longer duration of action was implicitly desirable, the present study, carried out in eleven patients with coronary artery disease and stable, exertional angina pectoris, was undertaken to assess the antiischemic effects of 8 mg molsidomine in sustained-release form as compared with the standard 2 mg formulation according to a double-blind, randomized, crossover, placebo-controlled protocol. Additionally, plasma concentrations of molsidomine were determined to elucidate the bioavailability as well as possible correlations between plasma concentrations and antiischemic effect. As compared with placebo, after administration of 8 mg molsidomine sustained-release there were reduction in the ST-segment depression at one, three, five and eight hours of 74% (p less than 0.001), 61% (p less than 0.001), 44% (p less than 0.025), and 31% (p less than 0.01), respectively; after 2 mg molsidomine, 74% (p less than 0.001), 37% (p less than 0.025), 7% (ns) and 6% (ns), respectively. Analysis of the response of the ST-segment in the individual patients showed an unequivocal antiischemic effect with a reduction in ST-segment depression of at least 1 mm after 8 mg molsidomine sustained-release at the specified points in time in ten, five, six and four patients, respectively, and after 2 mg molsidomine in nine, five, one and no patients, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

[Comparison of the anti-ischemia effect of nisoldipine and verapamil. Double-blind randomized cross-over and placebo-controlled acute and long-term study]

Nisoldipine (Bay K5552), a newly-developed dehydropyridine derivative with calcium antagonistic properties, was found to have a duration of action twice as long as its parent compound, nifedipine, in laboratory experiments. To evaluate the anti-ischemic potency and duration of action, the effects of 10 mg nisoldipine after acute administration and at the end of three weeks of treatment with 10 mg twice daily were compared with those of 120 mg verapamil three times daily in a double-blind, randomized, crossover, placebo-controlled study. In twelve patients with angiographically-documented coronary artery disease and stable exertional angina pectoris, bicycle ergometry was performed before and at three and seven hours after medication on the first and 21st days of the three respective treatment phases. The control value at 8 a.m. on the 21st day corresponded with the ten-hour value on the 20th day of treatment. Between the three treatment phases, there was a one-week wash-out period during which the patients received placebo three times daily. At the time of the ergometric studies, blood was drawn for determination of verapamil plasma concentrations and, additionally, each patient recorded anginal attacks and nitrate consumption. Analysis was carried out for ST-segment depression in each patient at the highest comparable workload achieved in all treatment phases, the time to onset of 1 mm ST-segment depression as well as the response of the heart rate, systolic arterial blood pressure and the heart rate-blood pressure double-product both at rest and during exercise.(ABSTRACT TRUNCATED AT 250 WORDS)

[Prevention of the development of tolerance to isosorbide dinitrate in interval therapy]

A number of carefully controlled studies in recent years have unequivocally documented evidence of tolerance development with respect to anti-ischemic effects during longterm treatment with nitrates [1, 3, 4, 5, 7, 8]. To determine to what extent tolerance development can be circumvented through an interval regimen, a study was performed in ten patients with stable angina pectoris and reproducible ST-segment depression according to a randomized, double-blind, cross-over, placebo-controlled protocol. Analysis of the anti-ischemic effect of 20 mg ISDN was carried out after acute administration and during chronic treatment on an interval regimen with the administration of 20 mg ISDN in the morning (at 8 a.m.) and at midday (1 p.m.) (Figure 1). On acute administration, 20 mg ISDN led to a reduction in ST-segment depression from 2.15 to 0.40 mm (p less than 0.01) and during longterm treatment from 2.25 to 0.40 mm (p less than 0.01) (Figure 2, Table 1). After acute administration the plasma concentration of ISDN was 9 ng/ml, 2-ISMN 34 ng/ml and 5-ISMN 149 ng/ml (Figure 5, Table 2). Of the control values during longterm treatment, a detectable level was found only for 5-ISMN with a concentration of 36 ng/ml while that of both 2-ISMN and ISDN was 0 ng/ml. On renewed administration, there was an increase of ISDN to 9 ng/ml, 2-ISMN to 37 ng/ml and 5-ISMN to 208 ng/ml.(ABSTRACT TRUNCATED AT 250 WORDS)

[Development of tolerance with regard to the anti-ischemic effect of isosorbide dinitrate in regular multiple daily administration]

In previous studies it had been shown that during longterm treatment of coronary artery disease with isosorbide dinitrate (ISDN) in sustained-release form, there was no reduction in exercise-induced ST-segment depression, no decrease in the rate of anginal attacks or nitrate consumption and no changes in blood pressure or heart rate [1, 4]. To determine to what extent tolerance development is a fundamental property of longterm administration of ISDN, this study, carried out according to a randomized, double-blind, cross-over, placebo-controlled protocol (Figure 1), was undertaken. The anti-ischemic effects of 40 mg ISDN were analyzed after acute administration and during longterm treatment with 40 mg four times daily in eleven patients with stable angina pectoris and reproducible ST-segment depression. Additionally, the influence of this therapy on the anti-ischemic effects of 0.8 mg sublingually-administered nitroglycerin (GTN) was assessed in ten of the eleven patients. On acute administration, 40 mg ISDN led to a reduction in ST-segment depression at one hour from 2.05 to 0.18 mm (p less than 0.01), and at six hours from 2.35 to 1.20 mm (p less than 0.01) (Figure 2, Table 1). During chronic treatment, statistically significant changes were no longer detectable. In eight of the eleven patients there was a complete loss of effects; in the remaining three, a marked attenuation was observed (Figure 3). Acute administration of 40 mg ISDN resulted in plasma concentrations of 221 ng/ml 5-ISMN, 53 ng/ml 2-ISMN and 23 ng/ml ISDN (Figure 6, Table 2).(ABSTRACT TRUNCATED AT 250 WORDS)