Quality and transparency of evidence for implantable cardiovascular medical devices assessed by the CORE-MD consortium

BACKGROUND AND AIMS

The European Union Medical Device Regulation 2017/745 challenges key stakeholders to follow transparent and rigorous approaches to the clinical evaluation of medical devices. The purpose of this study is a systematic evaluation of published clinical evidence underlying selected high-risk cardiovascular medical devices before and after market access in the European Union (CE-marking) between 2000 and 2021.

METHODS

Pre-specified strategies were applied to identify published studies of prospective design evaluating 71 high-risk cardiovascular devices in seven different classes (bioresorbable coronary scaffolds, left atrial appendage occlusion devices, transcatheter aortic valve implantation systems, transcatheter mitral valve repair/replacement systems, surgical aortic and mitral heart valves, leadless pacemakers, subcutaneous implantable cardioverter-defibrillator). The search time span covered 20 years (2000-21). Details of study design, patient population, intervention(s), and primary outcome(s) were summarized and assessed with respect to timing of the corresponding CE-mark approval.

RESULTS

At least one prospective clinical trial was identified for 70% (50/71) of the pre-specified devices. Overall, 473 reports of 308 prospectively designed studies (enrolling 97 886 individuals) were deemed eligible, including 81% (251/308) prospective non-randomized clinical trials (66 186 individuals) and 19% (57/308) randomized clinical trials (31 700 individuals). Pre-registration of the study protocol was available in 49% (150/308) studies, and 16% (48/308) had a peer-reviewed publicly available protocol. Device-related adverse events were evaluated in 82% (253/308) of studies. An outcome adjudication process was reported in 39% (120/308) of the studies. Sample size was larger for randomized in comparison to non-randomized trials (median of 304 vs. 100 individuals, P < .001). No randomized clinical trial published before CE-mark approval for any of the devices was identified. Non-randomized clinical trials were predominantly published after the corresponding CE-mark approval of the device under evaluation (89%, 224/251). Sample sizes were smaller for studies published before (median of 31 individuals) than after (median of 135 individuals) CE-mark approval (P < .001). Clinical trials with larger sample sizes (>50 individuals) and those with longer recruitment periods were more likely to be published after CE-mark approval, and were more frequent during the period 2016-21.

CONCLUSIONS

The quantity and quality of publicly available data from prospective clinical investigations across selected categories of cardiovascular devices, before and after CE approval during the period 2000-21, were deemed insufficient. The majority of studies was non-randomized, with increased risk of bias, and performed in small populations without provision of power calculations, and none of the reviewed devices had randomized trial results published prior to CE-mark certification.

Effect of phosphodiesterase-5 inhibition on SystEmic Right VEntricular size and function. A multicentre, double-blind, randomized, placebo-controlled trial: SERVE

AIMS

In adults with congenital heart disease and systemic right ventricles, progressive right ventricular systolic dysfunction is common and is associated with adverse outcomes. Our aim was to assess the impact of the phosphodiesterase-5-inhibitor tadalafil on right ventricular systolic function.

METHODS AND RESULTS

This was a double-blind, randomized, placebo-controlled, multicentre superiority trial (NCT03049540) involving 100 adults with systemic right ventricles (33 women, mean age: 40.7 ± 10.7 years), comparing tadalafil 20 mg once daily versus placebo (1:1 ratio). The primary endpoint was the change in right ventricular end-systolic volume after 3 years of therapy. Secondary endpoints were changes in right ventricular ejection fraction, exercise capacity and N-terminal pro-B-type natriuretic peptide concentration. Primary endpoint assessment by intention to treat analysis at 3 years of follow-up was possible in 83 patients (42 patients in the tadalafil group and 41 patients in the placebo group). No significant changes over time in right ventricular end-systolic volumes were observed in the tadalafil and the placebo group, and no significant differences between treatment groups (3.4 ml, 95% confidence interval -4.3 to 11.0, p = 0.39). No significant changes over time were observed for the pre-specified secondary endpoints for the entire study population, without differences between the tadalafil and the placebo group.

CONCLUSIONS

In this trial in adults with systemic right ventricles, right ventricular systolic function, exercise capacity and neuro-hormonal activation remained stable over a 3-year follow-up period. No significant treatment effect of tadalafil was observed. Further research is needed to find effective treatment for improvement of ventricular function in adults with systemic right ventricles.

Enoxaparin for primary thromboprophylaxis in symptomatic outpatients with COVID-19 (OVID): a randomised, open-label, parallel-group, multicentre, phase 3 trial

Background

COVID-19 is a viral prothrombotic respiratory infection. Heparins exert antithrombotic and anti-inflammatory effects, and might have antiviral properties. We aimed to investigate whether thromboprophylaxis with enoxaparin would prevent untoward hospitalisation and death in symptomatic, but clinically stable outpatients with COVID-19.

Methods

OVID was a randomised, open-label, parallel-group, investigator-initiated, phase 3 trial and was done at eight centres in Switzerland and Germany. Outpatients aged 50 years or older with acute COVID-19 were eligible if they presented with respiratory symptoms or body temperature higher than 37·5°C. Eligible participants underwent block-stratified randomisation (by age group 50–70 vs >70 years and by study centre) in a 1:1 ratio to receive either subcutaneous enoxaparin 40 mg once daily for 14 days versus standard of care (no thromboprophylaxis). The primary outcome was a composite of any untoward hospitalisation and all-cause death within 30 days of randomisation. Analysis of the efficacy outcomes was done in the intention-to-treat population. The primary safety outcome was major bleeding. The study was registered in ClinicalTrials.gov (NCT04400799) and has been completed.

Findings

At the predefined formal interim analysis for efficacy (50% of total study population), the independent Data Safety Monitoring Board recommended early termination of the trial on the basis of predefined statistical criteria having considered the very low probability of showing superiority of thromboprophylaxis with enoxaparin for the primary outcome under the initial study design assumptions. Between Aug 15, 2020, and Jan 14, 2022, from 3319 participants prescreened, 472 were included in the intention-to-treat population and randomly assigned to receive enoxaparin (n=234) or standard of care (n=238). The median age was 57 years (IQR 53–62) and 217 (46%) were women. The 30-day risk of the primary outcome was similar in participants allocated to receive enoxaparin and in controls (8 [3%] of 234 vs 8 [3%] of 238; adjusted relative risk 0·98; 95% CI 0·37–2·56; p=0·96). All hospitalisations were related to COVID-19. No deaths were reported during the study. No major bleeding events were recorded. Eight serious adverse events were recorded in the enoxaparin group versus nine in the control group.

Interpretation

These findings suggest thromboprophylaxis with enoxaparin does not reduce early hospitalisations and deaths among outpatients with symptomatic COVID-19. Futility of the treatment under the initial study design assumptions could not be conclusively assessed owing to under-representation of older patients and consequent low event rates.

Funding

SNSF (National Research Programme COVID-19 NRP78: 198352), University Hospital Zurich, University of Zurich, Dr-Ing Georg Pollert (Berlin), Johanna Dürmüller-Bol Foundation.

Enoxaparin for primary thromboprophylaxis in ambulatory patients with coronavirus disease-2019 (the OVID study): a structured summary of a study protocol for a randomized controlled trial

Objectives

The OVID study will demonstrate whether prophylactic-dose enoxaparin improves survival and reduces hospitalizations in symptomatic ambulatory patients aged 50 or older diagnosed with COVID-19, a novel viral disease characterized by severe systemic, pulmonary, and vessel inflammation and coagulation activation.

Trial design

The OVID study is conducted as a multicentre open-label superiority randomised controlled trial.

Participants

Inclusion Criteria

1. Signed patient informed consent after being fully informed about the study’s background.

2. Patients aged 50 years or older with a positive test for SARS-CoV2 in the past 5 days and eligible for ambulatory treatment.

3. Presence of respiratory symptoms (i.e. cough, sore throat, or shortness of breath) or body temperature >37.5° C.

4. Ability of the patient to travel to the study centre by private transportation, performed either by an accompanying person from the same household or by the patient themselves

5. Ability to comply with standard hygiene requirements at the time of in-hospital visit, including a face mask and hand disinfectant.

6. Ability to walk from car to study centre or reach it by wheelchair transport with the help of an accompanying person from the same household also complying with standard hygiene requirements.

7. Ability to self-administer prefilled enoxaparin injections after instructions received at the study centre or availability of a person living with the patient to administer enoxaparin.

Exclusion Criteria

1. Any acute or chronic condition posing an indication for anticoagulant treatment, e.g. atrial fibrillation, prior venous thromboembolism (VTE), acute confirmed symptomatic VTE, acute coronary syndrome.

2. Anticoagulant thromboprophylaxis deemed necessary in view of the patient's history, comorbidity or predisposing strong risk factors for thrombosis:

 a. Any of the following events occurring in the prior 30 days: fracture of lower limb, hospitalization for heart failure, hip/knee replacement, major trauma, spinal cord injury, stroke,

 b. previous VTE,

 c. histologically confirmed malignancy, which was diagnosed or treated (surgery, chemotherapy, radiotherapy) in the past 6 months, or recurrent, or metastatic, or inoperable.

3. Any clinically relevant bleeding (defined as bleeding requiring hospitalization, transfusion, surgical intervention, invasive procedures, occurring in a critical anatomical site, or causing disability) within 30 days prior to randomization or sign of acute bleeding.

4. Intracerebral bleeding at any time in the past or signs/symptoms consistent with acute intracranial haemorrhage.

5. Haemoglobin <8 g/dL and platelet count <50 x 10⁹ cells/L confirmed by recent laboratory test (<90 days).

6. Subjects with any known coagulopathy or bleeding diathesis, including known significant liver disease associated with coagulopathy.

7. Severe renal insufficiency (baseline creatinine clearance <30 mL/min calculated using the Cockcroft-Gault formula) confirmed by recent laboratory test (<90 days).

8. Contraindications to enoxaparin therapy, including prior heparin-induced thrombocytopenia and known hypersensitivity.

9. Current use of dual antiplatelet therapy.

10. Participation in other interventional studies over the past 30 days.

11. Non-compliance or inability to adhere to treatment or lack of a family environment or support system for home treatment.

12. Cognitive impairment and/or inability to understand information provided in the study information.

Patient enrolment will take place at seven Swiss centres, including five university hospitals and two large cantonal hospitals.

Intervention and comparator

Patients randomized to the intervention group will receive subcutaneous enoxaparin at the recommended dose of 4,000 IU anti-Xa activity (40 mg/0.4 ml) once daily for 14 days. Patients randomized to the comparator group will receive no anticoagulation.

Main outcomes

Primary outcome: a composite of any hospitalization or all-cause death occurring within 30 days of randomization.

Secondary outcomes: (i) a composite of cardiovascular events, including deep vein thrombosis (including catheter-associated), pulmonary embolism, myocardial infarction/myocarditis, arterial ischemia including mesenteric and extremities, acute splanchnic vein thrombosis, or ischemic stroke within 14 days, 30 days, and 90 days of randomization; (ii) each component of the primary efficacy outcome, within 14 days, 30 days, and 90 days of randomization; (iii) net clinical benefit (accounting for the primary efficacy outcome, composite cardiovascular events, and major bleeding), within 14 days, 30 days, and 90 days of enrolment; (iv) primary efficacy outcome, within 14 days, and 90 days of enrolment; (v) disseminated intravascular coagulation (ISTH criteria, in-hospital diagnosis) within 14 days, 30 days, and 90 days of enrolment.

Randomisation

Patients will undergo block stratified randomization (by age: 50-70 vs. >70 years; and by study centre) with a randomization ratio of 1:1 with block sizes varying between 4 and 8. Randomization will be performed after the signature of the informed consent for participation and the verification of the eligibility criteria using the electronic data capture software (REDCAP, Vanderbilt University, v9.1.24).

Blinding (masking)

In this open-label study, no blinding procedures will be used.

Numbers to be randomised (sample size)

The sample size calculation is based on the parameters α = 0.05 (2-sided), power: 1−β = 0.8, event rate in experimental group, pexp = 0.09 and event rate in control group, pcon = 0.15. The resulting total sample size is 920. To account for potential dropouts, the total sample size was fixed to 1000 with 500 patients in the intervention group and 500 in the control group.

Trial Status

Protocol version 1.0, 14 April 2020. Protocol version 3.0, 18 May 2020

Recruiting start date: June 2020.

Last Patient Last Visit: March 2021.

Trial registration

ClinicalTrials.gov Identifier: NCT04400799

First Posted: May 26, 2020

Last Update Posted: July 16, 2020

Full protocol

The full protocol is attached as an additional file, accessible from the Trials website (Additional file 1). In the interest in expediting dissemination of this material, the familiar formatting has been eliminated; this Letter serves as a summary of the key elements of the full protocol.

Locked internal fixator: sensitivity of screw/plate stability to the correct insertion angle of the screw

OBJECTIVE

Internal fixators with angular stability have been developed to provide high stability without compression of the plate on to the bone. Angular and axial stability of a plate-screw construct can be achieved using a conically threaded screw head undersurface and a corresponding conically threaded plate hole. Furthermore, the insertion angle of the screw must correspond precisely to the axis of the screw hole. This is not always achieved in clinical practice and may result in screw loosening. The objective of this study was to examine the relationship between the stability of the locked screw-plate on the insertion angle of the screw.

METHODS

Locking screws were inserted in an isolated (Point Contact Fixator, PC-Fix) or combined (Locking Compression Plate, LCP 4.5) locking hole with the use of an aiming device. The optimal insertion angle for these plates is perpendicular to the plate surface. The screws were inserted with an axis deviation of 0 degrees (optimal condition), 5 degrees , and 10 degrees respective to the optimal angle (variance +/- 1 degrees ). The samples were tested under shear or axial (push out) loading conditions until failure occurred. An Instron materials testing machine was used.

RESULTS

Locking screws inserted in the isolated locking hole (PC-Fix) showed a significant decrease of failure load if inserted at 5 degrees and 10 degrees angle. Using an optimal insertion angle (0 degrees ), failure load was 1480 +/- 390 N, with 5 degrees axis deviation 780 +/- 160 N, P = 0.0001, and with 10 degrees axis deviation 550 +/- 110 N, P = 0.0001. Screws inserted in the combined locking hole (LCP) also showed a significant decrease of push-out force of 77% (4960 +/- 1000 N versus 1120 +/- 400 N) with 10 degrees axis deviation. Compared to optimal insertion angle (0 degrees ), bending load to failure did decrease up to 69% (1240 +/- 210 N vs. 390 +/- 100 N) with 10 degrees axis deviation.

CONCLUSION

A locking head screw exhibits high stability with a moderate axis deviation in the angle of insertion of up to 5 degrees . However, there is a significant decrease in stability with increasing axis deviation (>5 degrees ). An aiming device is recommended to provide optimal fixation with angular stability.

LISS PLT: design, mechanical and biomechanical characteristics

Following the development of the Less Invasive Sabilization System for Distal Femur a similar system for proximal tibia fractures (LISS PLT) was designed. Anatomical studies were carried out to define the shape of the plate and the position and orientation of the screws. Standard mechanical tests were performed to ensure that the LISS PLT fixation provides similar fatigue resistance to that of conventional plates. Finally, cadaver tibia pairs were used to compare the biomechanical performance of the new device to that of bilateral plating. An unstable intra-articular proximal tibia fracture model was used. The medial condyle of the tibias were submitted to loading cycles with increasing load levels and the vertical subsidence of the medial condyle during the loading cycles was monitored. Comparable stability against secondary loss of reduction was observed for the LISS PLT and the bilateral plating constructs.

The development of the distal femur Less Invasive Stabilization System (LISS)

Fractures around the knee typically require operative fixation to achieve an acceptable, functional outcome. The idea behind the Less Invasive Stabilization System (LISS) was to combine the advantages of both interlocked intramedullary nailing techniques and the early advances of the so-called biological plating technique into one system. This paper introduces the mechanical concept of a locked internal fixator and details some important aspects of the anatomical and biomechanical development of the LISS.

Biomechanical evaluation of the less invasive stabilization system for the internal fixation of distal femur fractures

OBJECTIVE

Comparison between a Less Invasive Stabilization System (LISS) using monocortical screws with angular stability and two conventional plate systems Condylar Buttress Plate (CBP) and Dynamic Condylar Screw (DCS) for the treatment of distal femoral fractures with respect to biomechanical properties.

DESIGN

Biomechanical study using paired cadaver femurs. In Test Configuration 1 (distal test), a ten-millimeter gap at the diaphysis-metaphysis junction simulates a supracondylar femoral fracture. Test Configuration 2 (proximal test) has the same configuration, but the gap was cut in the isthmic region. Proximal and distal plate ends were fixed to corresponding cortical bone fragments in both tests. Optical displacement transducers served to quantify the system's ability to withstand a stepwise increased load. Reversible (deflection) and irreversible deformation (subsidence) of the bone-plate construct was investigated.

RESULTS

In Test Configuration 1, LISS showed less irreversible deformation in 72 percent of the left-right comparisons. No correlation between bone mineral density, cross-section area of bones and the measured response of the construct under load was found between pairs. In Test Configuration 2, 83 percent of the left-right comparisons showed less permanent deformation but a higher elastic deformation for LISS.

CONCLUSIONS

These results suggest an enhanced ability to withstand high loads when using the monocortical screw fixation technique with angular stability. A higher elastic deformation of LISS compared with conventional plating systems in distal femoral fractures can be explained by the lower bending stiffness caused by different design and material properties.