Early and long-term (one-year) effects of the association of aspirin and oral anticoagulant on thrombi and morbidity after replacement of the mitral valve with the St. Jude medical prosthesis: a clinical and transesophageal echocardiographic study

Management of prosthetic valve thrombosis with unfractionated heparin

BACKGROUND

Prosthetic valve thrombosis (PVT) is a severe and life-threatening complication. Surgery and thrombolytic therapy (TT) carry a high risk, and in several circumstances, optimal anticoagulation with unfractionated heparin (UFH) infusion may be an alternative treatment. This study aimed to assess the results of UFH in patients diagnosed with both obstructive and non-obstructive PVT.

METHODS

This observational retrospective study enrolled patients who had contraindications for TT and surgery underwent UFH therapy.

RESULTS

A total of 136 patients were enrolled [male: 55 (40.4%), mean age: 50.3 ± 14.6 years] in the study. In the successful group, 66 patients (48,5%) showed >75% regression in the thrombus burden without facing death or major non-fatal complications.In the unsuccessful group, 56 had less than a 50% reduction in thrombus load and 14 (10.3%) suffered major complications. The presence of obstruction (27.1% vs. 12.1%; p = 0.028), thrombus area 1.1 cm2 vs. 0.8 cm2; p = 0.005] and the duration of UFH treatment (15.1 vs. 11.8 (days); p = 0.005) were significantly higher in the unsuccessful UFH group.In multivariate regression analyses the presence of obstruction (RR: 3.088, p = 0.020), increased thrombus area (RR: 2.400; p = 0.015), and increased duration of UFH therapy (RR: 1.073 95%, p = 0.012) were identified as independent predictive parameters for a failed UFH therapy.

CONCLUSIONS

This study suggests that UFH therapy may be considered a relatively beneficial treatment strategy for some patients with PVT. The most significant factors affecting success are the obstructive nature and area of the thrombus.

Outcomes of Patients with a Mechanical Heart Valve and Poor Anticoagulation Control on Warfarin

BACKGROUND

 Patients with a mechanical heart valve (MHV) require oral anticoagulation. Poor anticoagulation control is thought to be associated with adverse outcomes, but data are limited.

OBJECTIVE

 To assess the risks of clinical outcomes in patients with a MHV and poor anticoagulation control on warfarin.

PATIENTS/METHODS

 We conducted a retrospective study of consecutive patients undergoing MHV implantation at a tertiary care center (2010-2019). Primary outcome was a composite of ischemic stroke, systemic embolism, or prosthetic valve thrombosis. Major bleeding and death were key secondary outcomes. We constructed multivariable regression models to assess the association between time in therapeutic range (TTR) on warfarin beyond 90 days after surgery with outcomes.

RESULTS

 We included 671 patients with a MHV (80.6% in aortic, 14.6% in mitral position; mean age 61 years, 30.3% female). Median follow-up was 4.9 years, mean TTR was 62.5% (14.5% TTR <40%, 24.6% TTR 40-60%, and 61.0% TTR >60%). Overall rates of the primary outcome, major bleeding, and death were 0.73, 1.41, and 1.44 per 100 patient-years. Corresponding rates for patients with TTR <40% were 1.31, 2.77, and 3.22 per 100 patient-years. In adjusted analyses, every 10% decrement in TTR was associated with a 31% increase in hazard for the primary outcome (hazard ratio [HR]: 1.31, 95% confidence interval [CI]: 1.13-1.52), 34% increase in major bleeding (HR: 1.34, 95% CI: 1.17-1.52), and 32% increase in death (HR: 1.32, 95% CI: 1.11-1.57).

CONCLUSION

 In contemporary patients with a MHV, poor anticoagulation control on warfarin was associated with increased risks of thrombotic events, bleeding, and death.

Antithrombotic Therapy for Primary and Secondary Prevention of Ischemic Stroke: JACC State-of-the-Art Review

Stroke is a devastating condition with significant morbidity and mortality worldwide. Antithrombotic therapy plays a crucial role in both primary and secondary prevention of stroke events. Single or dual antiplatelet therapy is generally preferred in cases of large-artery atherosclerosis and small-vessel disease, whereas anticoagulation is recommended in conditions of blood stasis or hypercoagulable states that mostly result in red thrombi. However, the benefit of antithrombotic therapies must be weighed against the increased risk of bleeding, which can pose significant challenges in the pharmacological management of this condition. This review provides a comprehensive summary of the currently available evidence on antithrombotic therapy for ischemic stroke and outlines an updated therapeutic algorithm to support physicians in tailoring the strategy to the individual patient and the underlying mechanism of stroke.

Mechanical valve thrombosis: current management and differences between guidelines

All foreign bodies inserted in the circulatory system are thrombogenic and require temporary or lifelong antithrombotic therapies to prevent thrombosis. The adequate level of anticoagulation during the first few months determines the long-term durability, particularly for mechanical prostheses;2 however also for biological valves. Suboptimal anticoagulation is the most frequent source of mechanical valve thrombosis (MVT). The patient's clinical presentation decides how mechanical prosthetic valve obstruction is managed. If the mechanical valve thrombosis is obstructive and the patient is in a critical condition with hemodynamic instability, an immediate surgical intervention should be performed. The thrombolytic treatment is an option for left mechanical valve thrombosis in patients who have high surgical risk and no contraindications and also for right heart valve thrombosis. In non-obstructive thrombosis on the mechanical valve, patients can be asymptomatic, requiring optimization of the anticoagulant treatment. Both obstructive and non-obstructive thrombus generated on the mechanical prosthesis can result in embolic events. After anticoagulant treatment, if the thrombus persists the indication is for thrombolytic treatment or redo surgery. Pannus can also cause obstruction of the prosthesis for which surgical treatment is the only option. All these clinical scenarios seem to have a simple solution in terms of surgery vs thrombolysis vs effective anticoagulation, but the real-world clinical experience could be different. For example, the same patient with some common comorbidities, non-obstructive mechanical valve thrombosis, and symptomatic only by repeated systemic embolizations, can go through all these 3 therapeutic options, due to MVT's unpredictable nature. Therefore, treatment indications can intersect both on the time axis and depending on the patient's clinical status and the expertise of the center where he is hospitalized. Moreover, the European and American guidelines show subtle but important differences. The aim of this review was to compare these differences, comment on recent studies and evidence gaps, propose a more pragmatic algorithm combining all current indications, and highlight important research directions for this disease that has dominated already the cardiovascular landscape for more than five decades, but for which there have been no significant recent changes in management.

Oral anticoagulant management of patients with mechanical heart valves at the Salam Centre of Khartoum: Observations on quality of anticoagulation and thrombotic risk

INTRODUCTION

Rheumatic heart disease with mechanical heart valve (MHV) replacement is common in Africa. However, MHV requires long-life anticoagulation and managing this can be challenging.

METHODS AND RESULTS

We report data of a prospective observational study conducted between August 2018 and September 2019 in MHV patients in the Salam Centre for Cardiac Surgery built in Khartoum, by Emergency, an Italian Non-Governmental Organization, to evaluate the quality of anticoagulation control and the risk of thrombotic complications.

RESULTS

We studied 3647 patients (median age 25.1 years; 53.9 % female). Median Time in Therapeutic Range (TTR) was 53 % (interquartile range 37 % to 67 %) and 70 thrombotic events (rate 1.8 × 100 pt-years [95 % CI 1.38-2.23]) were recorded. Among patients in the first quartile of TTR (≤37 %), we recorded 34/70 (48.6 %) of all thrombotic events (rate 3.7 × 100 pt-years [95 % CI 2.5-5.1]), with a high mortality rate (2.2 × 100 pt-years [95 % CI 1.3-3.3]). In patients with guideline-recommended TTR (≥65 %) the event rate was 0.8 × 100 pt-years for thrombotic events [95 % CI 0.3-1.5] and 0.4 × 100 pt-years for mortality [95 % CI 0.1-0.9]. Multivariable analysis showed that having a TTR in the lowest quartile (≤37 %) and being noncompliant are significantly associated with increased thrombotic risk. Aspirin use or different valve type did not influence the thrombotic risk. Almost 40 % of all thromboembolic complications could have been potentially prevented by further improving VKA management to obtain a TTR > 37 %.

CONCLUSION

The thrombotic risk of MHV patients on VKAs living in a low-income country like Sudan is associated with low quality of anticoagulation control. Efforts should be made to decrease the number of non-compliant patients and to reach a guideline-recommended TTR of ≥65 %.

Editorial commentary: Cutting the Gordian knot of right-sided prosthetic valve thrombosis

With limited data available for the tricuspid valve, there are no stringent recommendations in the current guidelines (ESC 2021). Valve replacement for the right-sided heart is inherently problematic and bears the potential for complications - including prosthetic valve thrombosis (PVT). The purpose of this editorial is to review the key features of this clinical scenario and to outline the essential aspects for optimized patient management and improved outcome. Depending on the clinical presentation of PVT, either immediate surgery, thrombolysis, or anticoagulation may be considered - with the sole intensification of anticoagulation likely being the most inferior. Given the high risk of re-thrombosis, a dedicated follow-up program is essential to identify complications early and offer adequate treatment.

Antithrombotic Treatment After Surgical and Transcatheter Heart Valve Repair and Replacement

New antithrombotic drugs have been developed, new valve types have been designed and minimally invasive transcatheter techniques have emerged, making the choice of antithrombotic therapy after surgical or transcatheter heart valve repair and replacement increasingly complex. Moreover, due to a lack of large randomized controlled trials many recommendations for antithrombotic therapy are based on expert opinion, reflected by divergent recommendations in current guidelines. Therefore, decision-making in clinical practice regarding antithrombotic therapy for prosthetic heart valves is difficult, potentially resulting in sub-optimal patient treatment. This article compares the 2017 ESC/EACTS and 2020 ACC/AHA guidelines on the management of valvular heart disease and summarizes the available evidence. Finally, we established a convenient consensus on antithrombotic therapy after valve interventions based on over 800 annual cases of surgical and transcatheter heart valve repair and replacement and a multidisciplinary team discussion between the department of cardiovascular diseases and cardiac surgery of the University Hospitals Leuven, Belgium.

American Society of Hematology 2020 guidelines for management of venous thromboembolism: treatment of deep vein thrombosis and pulmonary embolism

BACKGROUND

Venous thromboembolism (VTE), which includes deep vein thrombosis (DVT) and pulmonary embolism (PE), occurs in ∼1 to 2 individuals per 1000 each year, corresponding to ∼300 000 to 600 000 events in the United States annually.

OBJECTIVE

These evidence-based guidelines from the American Society of Hematology (ASH) intend to support patients, clinicians, and others in decisions about treatment of VTE.

METHODS

ASH formed a multidisciplinary guideline panel balanced to minimize potential bias from conflicts of interest. The McMaster University GRADE Centre supported the guideline development process, including updating or performing systematic evidence reviews. The panel prioritized clinical questions and outcomes according to their importance for clinicians and adult patients. The Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach was used to assess evidence and make recommendations, which were subject to public comment.

RESULTS

The panel agreed on 28 recommendations for the initial management of VTE, primary treatment, secondary prevention, and treatment of recurrent VTE events.

CONCLUSIONS

Strong recommendations include the use of thrombolytic therapy for patients with PE and hemodynamic compromise, use of an international normalized ratio (INR) range of 2.0 to 3.0 over a lower INR range for patients with VTE who use a vitamin K antagonist (VKA) for secondary prevention, and use of indefinite anticoagulation for patients with recurrent unprovoked VTE. Conditional recommendations include the preference for home treatment over hospital-based treatment for uncomplicated DVT and PE at low risk for complications and a preference for direct oral anticoagulants over VKA for primary treatment of VTE.

Anticoagulation and antiplatelet therapy in patients with prosthetic heart valves

BACKGROUND

The choice of antithrombotic therapy, anticoagulants or antiplatelets, after prosthetic heart valve replacement or repair, remains a disputed topic in the literature. Antithrombotic therapies are used after heart valve intervention to reduce the rates of thromboembolic events, therefore improving patient outcomes. Different interventions may require different therapeutic regimens to achieve the most efficacious clinical outcome for patients.

METHODS AND DISCUSSION

This review aims to summarize and critique the available literature concerning therapeutic agents used for bioprosthetic and mechanical valves as well as for valve repair, so as to assist clinicians and researchers in making decisions with regard to their patients and research endeavors.

Genotype-guided warfarin dosing may benefit patients with mechanical aortic valve replacements: randomized controlled study

This prospective, single-blind, randomized study was designed to evaluate the effect of genotype-based warfarin dosing compared with standard warfarin dosing in Korean patients with mechanical cardiac valves. Patients were assigned to either the genotype-based dosing group or the standard dosing group using stratified block randomization. The genotype-based dosing equation was adopted from a previous study which included VKORC1 rs9934438, CYP2C9 rs1057910, CYP4F2 rs2108622, and age. Primary outcomes included the percentage of time in the therapeutic range (pTTR): (i) during the first week following initiation of warfarin therapy, (ii) during hospitalization and (iii) until the first outpatient visit. A total of 91 patients were included in the analysis, 42 treated with genotype-based warfarin dosing and 49 treated with standard warfarin dosing. The genotype frequency differences of the three SNPs included in this study (ie, VKORC1, CYP2C9, CYP4F2), between the genotype-based dosing and standard dosing groups were not different. The genotype-based dosing group trended toward higher pTTR when compared with the standard dosing group, although this difference was not statistically significant. In patients with aortic valve replacement, TTR_Traditional and TTR_Rosendaal were significantly higher in the genotype-based dosing group when compared with the standard dosing group during the first week following treatment initiation [ie, 58.5% vs. 38.1% (p = 0.009) and 64.0% vs. 44.6% (p = 0.012), respectively]. Based on the results, the genotype-guided dosing did not offer a significant clinical advantage, but a possible benefit in patients with aortic valve replacement has been suggested.

Optimal oral anticoagulant therapy in Chinese patients with mechanical heart valves

BACKGROUND

The oral administration of anticoagulants is an effective means of preventing thromboembolic complications in patients implanted with mechanical valves. This treatment strategy, however, entails a dose-dependent in the risk of hemorrhage that is a cause for concern in China. As such, in this study, we sought to better determine what the ideal oral anticoagulant therapy intensity is in a Chinese population of patients implanted with mechanical valves.

METHODS

In the present observational cohort study, we observed the outcomes of eligible enrolled patients that had been implanted with St. Jude Medical prosthetic valves and who had been treated at our institution from 2013 onwards. All enrolled patients were followed for between 1 and 6 years through outpatient visits or telephone interviews following discharge. Study endpoints included instances of thromboembolism and major hemorrhage. We calculated the international normalized ratio (INR)-specific incidence of such adverse events as a means of determining optimal anticoagulant therapeutic intensity in patients with these bileaflet mechanical valve prostheses.

RESULTS

In total this study enrolled 3176 patients, of whom 3017 were followed for 12,746.08 total person-years (4.22 mean years per patient), while the remaining 159 patients (5%) were lost during follow-up. A total of 182 patients suffered from adverse events, with a roughly 1.43% annual incidence rate of such adverse events (95% confidence interval [CI], 1.22-1.64). Of these, 54 patients suffered from episodes of major bleeding (0.42% per patient-year, 95% CI, 0.31-0.53), while 131 suffered from thromboembolism (1.03% per patient-year, 95% CI, 0.85-1.21). Based on these analyses, we determined that the ideal low-intensity anticoagulant treatment regimen for patients with bileaflet mechanical heart valve prostheses was an INR between 1.5 and 2.5. In those patients that had undergone aortic valve replacement (AVR), the optimal INR was between 1.5 and 2.0 regardless of any thromboembolism risk factors in these patients. In contrast, in patients that had undergone mitral valve replacement (MVR) who were not at risk for thromboembolism, the optimal INR was between 1.5 and 2.0, whereas in those at risk of thromboembolism the optimal INR was between 2.0 and 2.5. The ideal anticoagulant intensity in patients undergoing both AVR and MVR (DVR) was the same as in patients undergoing MVR alone.

CONCLUSIONS

In order to achieve optimal outcomes by maintaining effective anticoagulant dosing while entailing minimal risk in Chinese patients that have undergone a bileaflet mechanical valve replacement, the target INR range should be between 1.5 and 2.5, with the final intensity of this anticoagulant regimen being determined based on a given patient's risk of thromboembolism.

Recurrent valve obstruction in a patient with a pure carbon bileaflet metallic mitral valve: a case report

Background

Despite overcoming the morbidity from severe native valve disease, prosthetic metallic valve replacement is not without its inherent morbidity, in particular from prosthetic valve thrombosis (PVT). The contemporary pure carbon bileaflet metallic valve confers reduced thrombogenicity.

Case Summary

We describe the case of a 45-year-old woman with a pure carbon bileaflet metallic mitral valve replacement (27/29 mm On-X) 6 months previously for severe rheumatic mitral stenosis, who presented with a rapid onset of dyspnoea, paroxysmal nocturnal dyspnoea, and haemoptysis. This was preceded by an interruption in therapeutic anticoagulation. On admission the patient was in cardiogenic shock. Transthoracic and transoesophageal (TOE) echocardiograms revealed increased transmitral gradients with disc hypomobility, suggestive of PVT, unexpected given the favourable safety profile of the On-X valve. Fluoroscopy confirmed the findings. The patient was thrombolysed successfully with alteplase, with restoration of normal transmitral gradients. A target international normalized ratio of 3.5–4.5 was chosen, in addition to aspirin 75 mg, to minimize thrombotic sequalae. Repeat TOE 6 weeks later revealed disc hypomobilty with a large adherent clot. Due to the high risks from thrombolysis, emergency redo-mitral bioprosthetic valve surgery was performed, to negate the need for long-term anticoagulation.

Discussion

Subtherapeutic anticoagulation and the rapid development of dyspnoea, should prompt the clinician to suspect PVT. Thorough clinical examination and immediate bedside echocardiography are critical for assessing prosthetic valve patients in cardiogenic shock. The treatment of PVT is complex, with considerable risks to the patient, irrespective of the strategy (thrombolysis/emergency valve replacement), necessitating the expertise of cardiologists and cardiac surgeons.

Time to achieving therapeutic international normalized ratio increases hospital length of stay after heart valve replacement surgery

BACKGROUND

Achieving a therapeutic international normalized ratio (INR) before hospital discharge is an important inpatient goal for patients undergoing mechanical cardiac valve replacement (MCVR). The use of clinical algorithms has reduced the time to achieve therapeutic INR (TTI) with warfarin therapy. Whether TTI prolongs length of stay (LOS) is unknown.

METHODS

Patients who underwent MCVR over a consecutive 42-month period were included. Clinical data were obtained from the Society of Thoracic Surgeons Adult Cardiac Surgery database and electronic medical records. Therapeutic INR was defined as per standard guidelines. Warfarin dose was prescribed using an inpatient pharmacy-managed algorithm and computer-based dosing tool. International normalized ratio trajectory, procedural needs, and drug interactions were included in warfarin dose determination.

RESULTS

There were 708 patients who underwent MCVR, of which 159 were excluded for reasons that would preclude or interrupt warfarin use. Among the remainder of 549 patients, the average LOS was 6.4days and mean TTI was 3.5days. Landmark analysis showed that subjects in hospital on day 4 (n=542) who achieved therapeutic INR were more likely to be discharged by day 6 compared with those who did not achieve therapeutic INR (75% vs 59%, P<.001). Multivariable proportional hazards regression with TTI as a time-dependent effect showed a strong association with discharge (P=.0096, hazard ratio1.3) after adjustment for other significant clinical covariates.

CONCLUSIONS

Time to achieve therapeutic INR is an independent predictor of LOS in patients requiring anticoagulation with warfarin after MCVR surgery. Alternative dosing and anticoagulation strategies will need to be adopted to reduce LOS in these patients.

Anticoagulation for prosthetic heart valves: unresolved questions requiring answers

PURPOSE OF REVIEW

The efficacy of anticoagulation for valvular prostheses is the result of a delicate balance between the risk of thromboembolic (TE) events and bleeding. Here, we review data on anticoagulation for valve prostheses with a focus on clinical trials that address key unanswered questions.

RECENT FINDINGS

There are several unanswered questions in the field of prosthetic valve anticoagulation, including: optimal TE prophylaxis in the short term for bioprostheses, optimal TE prophylaxis following transcatheter aortic valve implantation, the safety and efficacy of lower levels of anticoagulation with the bileaflet mechanical prosthesis, the role of aspirin for patients with mechanical prostheses, and the management of anticoagulation for mechanical valves in pregnancy. Other areas of study include the role, if any, of nonwarfarin oral anticoagulants for prosthetic TE prophylaxis as well as self-INR monitoring. Finally, we briefly mention studies of newer anticoagulants, such as novel vitamin K antagonists and antisense oligonucleotides, that are on the horizon.

SUMMARY

Optimal antithrombotic management is a key issue for patients with valvular prostheses, and the publication of recent trials has provided much-needed guidance. We highlight areas of progress, in addition to the major unanswered questions for which well-designed, prospective clinical trials are forthcoming.

Economic Evaluation of the Combined Use of Warfarin and Low-dose Aspirin Versus Warfarin Alone in Mechanical Valve Prostheses

BACKGROUND

The use of combined therapy of antiplatelet and anticoagulant versus anticoagulant alone to reduce instances of thromboembolic events in patients with heart valve prostheses is an established standard of care in many countries but not in Egypt. A previous Markov model cost-effectiveness study on Egyptian patients aged 50-60 years demonstrated that the combined therapy reduces the overall treatment cost. However, due to the lack of actual real-world data on cost-effectiveness and the limitation of the Markov model study to 50- to 60-year-old patients, the Egyptian medical community is still questioning whether the added benefit is worth the cost.

OBJECTIVE

To assess, from the perspective of the Egyptian health sector, the cost-effectiveness of the combined use of warfarin and low-dose aspirin (75 mg) versus that of warfarin alone in patients with mechanical heart valve prostheses who began therapy between the age of 15 and 50 years.

METHODS

An economic evaluation was conducted alongside a randomized, controlled trial to assess the cost-effectiveness of the combined therapy in patients with mechanical valve prostheses. A total of 316 patients aged between 15 and 50 years were included in the study and randomly assigned to a group treated with both warfarin and aspirin or a group treated with warfarin alone.

RESULTS

The patients in the combined therapy group exhibited a significantly longer duration of protection against the first event. Fewer primary events were observed in the patients treated with warfarin plus aspirin than in those treated with warfarin alone (1.4 %/year, vs. 4.8 %/year), and a higher mean quality-adjusted life-years (QALYs) value over 4 years was obtained for the group treated with warfarin plus aspirin (difference 0.058; 95 % CI 0.013-0.118), although this difference did not reach a conventional level of statistical significance. The total costs over a 4-year period were lower with the combined therapy (difference -US$244; 95 % CI -US$483.1 to -US$3.8), which yielded an incremental cost-effectiveness ratio of -US$4206 per QALY gained. Thus, the combined therapy was dominant. All costs were reported in US dollars (USD) for the financial year 2014.

CONCLUSIONS

The results of this analysis indicate that from the perspective of the Egyptian health sector, the addition of aspirin to the typical warfarin therapy is more effective and less costly for patients with mechanical valve prostheses than treatment with warfarin alone. This combined strategy could be adopted to prevent the complications of mechanical valve prostheses. Our study adds to the body of evidence supporting the option of warfarin-plus-aspirin therapy for patients with mechanical valve prostheses.

Low-Intensity Oral Anticoagulant Plus Low-Dose Aspirin During the First Six Months Versus Standard-Intensity Oral Anticoagulant Therapy After Mechanical Heart Valve Replacement: A Pilot Study of Low-Intensity Warfarin and Aspirin in Cardiac Prostheses (LIWACAP)

The objective of this study was to evaluate the safety and efficacy of low-intensity warfarin treatment plus aspirin during the first 6 months after surgery in patients undergoing heart valve substitution with mechanical prostheses. Vitamin K antagonists (VKA) are able to reduce but not eliminate thrombosis and systemic embolism in patients with mechanical heart valves. The intensity of treatment and additional use of aspirin in these patients is still controversial. Consecutive patients undergoing aortic or mitral valve replacement (or a combination of the two) with mechanical prostheses were invited to participate in the study. After stratifying for site of prosthesis, patients were randomized to receive low intensity VKA treatment (target INR 2.5) plus aspirin (100 mg/day) for the first six months (Group A) or standard-intensity (INR target 3.7) VKA treatment (Group B). Mean follow-up was 1.5 years. Principal outcome events were systemic embolism, major bleeding, and vascular death. A total of 94 patients in Group A and 104 in Group B were randomized and followed up for 144 and 163 patient years, respectively. There were 5 (5%) events in Group A (4 major bleeding events and 1 vascular death) and 4 (4%) in group B (2 major bleeding events and 2 ischemic stroke). All the events except 1 occurred within the first 6 months after surgery. Cumulative incidence of primary outcome events was 5.8% (95% CI 0.9 to 10.7) in Group A and 4.3% (95% CI 0,2 to 8.4) in Group B (p=0.6). Low-intensity treatment plus aspirin during the first six months after surgery appears to be as effective and safe as moderate-high-intensity anticoagulation.

Fibrinolytic Treatment after Transient Ischaemic Attack Caused by Prosthetic Mitral Valve Thrombosis

Prosthetic valve thrombosis is one of the most severe complications after surgical valve replacement. There are many possible presentations: from asymptomatic to life-threatening complications. We report on a 61-year-old female patient with prosthetic replacement of the aortic and mitral valve in the in-house department of cardiac surgery 3 months ago. The patient was suffering from aphasia during 5 minutes in domesticity. After her presentation in the emergency room, the echocardiographic examination revealed a thrombotic formation of the prosthetic mitral valve. At presentation, the anticoagulation was outside the effective range (INR: 1.7). A successful thrombolytic therapy with the plasminogen activator urokinase was begun with complete resolution of the thrombus.

Early postoperative bridging anticoagulation after mechanical heart valve replacement: a systematic review and meta-analysis

OBJECTIVE

To perform a systematic review and meta-analysis of studies evaluating anticoagulation during the early postoperative period following mechanical heart valve implantation.

METHODS

Five literature databases were searched to assess the rates of bleeding and thromboembolic events among patients receiving oral anticoagulation (OAC), both with and without bridging anticoagulation therapy with unfractionated heparin (UFH) or subcutaneous low molecular weight heparin (LMWH). The studies' results were pooled via a mixed effects meta-analysis. Heterogeneity (I(2) ) and publication bias were both evaluated.

RESULTS

Twenty-three studies including 9534 patients were included. The bleeding rates were 1.8% (95% confidence interval CI 1.0-3.3) in the group receiving OAC, 2.2% (95% CI 0.9-5.3) in the OAC + UFH group, and 5.5% (95% CI 2.9-10.4) in the OAC + LMWH group (P = 0.042). The thromboembolic event rate was 2.1% (95% CI 1.5-2.9) in the group receiving OAC, as compared with 1.1% (95% CI 0.7-1.8) when the bridging therapy groups were combined as follows: OAC + UFH and OAC + LMWH (P = 0.035). Most of the analyses showed moderate heterogeneity and negative test results for publication bias.

CONCLUSIONS

Bridging therapy following cardiac valve surgery was associated with a lower thromboembolic event rate, although the difference was small, with considerable overlap of the CIs. Direct comparisons are missing. Bridging therapy with UFH appears to be safe; however, this observation has a risk of bias. Early bridging therapy with LMWH appears to be associated with consistently high bleeding rates across multiple analyses. On the basis of the quality of the included studies, more trials are necessary to establish the clinical relevance of bridging therapy and the safety of LMWH.

Primary prophylaxis for venous thromboembolism in patients undergoing cardiac or thoracic surgery

BACKGROUND

Cardiac and thoracic surgery are associated with an increased risk of venous thromboembolism (VTE). The safety and efficacy of primary thromboprophylaxis in patients undergoing these types of surgery is uncertain.

OBJECTIVES

To assess the effects of primary thromboprophylaxis on the incidence of symptomatic VTE and major bleeding in patients undergoing cardiac or thoracic surgery.

SEARCH METHODS

The Cochrane Peripheral Vascular Diseases Group Trials Search Co-ordinator searched the Specialised Register (last searched May 2014) and CENTRAL (2014, Issue 4). The authors searched the reference lists of relevant studies, conference proceedings, and clinical trial registries.

SELECTION CRITERIA

Randomised controlled trials (RCTs) and quasi-RCTs comparing any oral or parenteral anticoagulant or mechanical intervention to no intervention or placebo, or comparing two different anticoagulants.

DATA COLLECTION AND ANALYSIS

We extracted data on methodological quality, participant characteristics, interventions, and outcomes including symptomatic VTE and major bleeding as the primary effectiveness and safety outcomes, respectively.

MAIN RESULTS

We identified 12 RCTs and one quasi-RCT (6923 participants), six for cardiac surgery (3359 participants) and seven for thoracic surgery (3564 participants). No study evaluated fondaparinux, the new oral direct thrombin, direct factor Xa inhibitors, or caval filters. All studies had major study design flaws and most lacked a placebo or no treatment control group. We typically graded the quality of the overall body of evidence for the various outcomes and comparisons as low, due to imprecise estimates of effect and risk of bias. We could not pool data because of the different comparisons and the lack of data. In cardiac surgery, 71 symptomatic VTEs occurred in 3040 participants from four studies. In a study of 2551 participants, representing 85% of the review population in cardiac surgery, the combination of unfractionated heparin with pneumatic compression stockings was associated with a 61% reduction of symptomatic VTE compared to unfractionated heparin alone (1.5% versus 4.0%; risk ratio (RR) 0.39; 95% confidence interval (CI) 0.23 to 0.64). Major bleeding was only reported in one study, which found a higher incidence with vitamin K antagonists compared to platelet inhibitors (11.3% versus 1.6%, RR 7.06; 95% CI 1.64 to 30.40). In thoracic surgery, 15 symptomatic VTEs occurred in 2890 participants from six studies. In the largest study evaluating unfractionated heparin versus an inactive control the rates of symptomatic VTE were 0.7% versus 0%, respectively, giving a RR of 6.71 (95% CI 0.40 to 112.65). There was insufficient evidence to determine if there was a difference in the risk of major bleeding from two studies evaluating fixed-dose versus weight-adjusted low molecular weight heparin (2.7% versus 8.1%, RR 0.33; 95% CI 0.07 to 1.60) and unfractionated heparin versus low molecular weight heparin (6% and 4%, RR 1.50; 95% CI 0.26 to 8.60).

AUTHORS' CONCLUSIONS

The evidence regarding the efficacy and safety of thromboprophylaxis in cardiac and thoracic surgery is limited. Data for important outcomes such as pulmonary embolism or major bleeding were often lacking. Given the uncertainties around the benefit-to-risk balance, no conclusions can be drawn and a case-by-case risk evaluation of VTE and bleeding remains preferable.

Antiplatelet and anticoagulation for patients with prosthetic heart valves

BACKGROUND

Patients with prosthetic heart valves are at increased risk for valve thrombosis and arterial thromboembolism. Oral anticoagulation alone, or the addition of antiplatelet drugs, has been used to minimise this risk. An important issue is the effectiveness and safety of the latter strategy.

OBJECTIVES

This is an update of our previous review; the goal was to create a valid synthesis of all available, methodologically sound data to further assess the safety and efficacy of combined oral anticoagulant and antiplatelet therapy versus oral anticoagulant monotherapy in patients with prosthetic heart valves.

SEARCH METHODS

We updated the previous searches from 2003 and 2010 on 16 January 2013 and searched the Cochrane Central Register of Controlled Trials (CENTRAL) on The Cochrane Library (2012, Issue 12), MEDLINE (OVID, 1946 to January Week 1 2013), and EMBASE (OVID, 1980 to 2013 Week 02). We have also looked at reference lists of individual reports, review articles, meta-analyses, and consensus statements. We included reports published in any language or in abstract form.

SELECTION CRITERIA

All reports of randomised controlled trials comparing standard-dose oral anticoagulation to standard-dose oral anticoagulation and antiplatelet therapy in patients with one or more prosthetic heart valves.

DATA COLLECTION AND ANALYSIS

Two review authors independently performed the search strategy, assessed trials for inclusion and study quality, and extracted data. We collected adverse effects information from the trials.

MAIN RESULTS

One new study has been identified and included in this update. In total, 13 studies involving 4122 participants were included in this review update. Years of publication ranged from 1971 to 2011. Compared with anticoagulation alone, the addition of an antiplatelet agent reduced the risk of thromboembolic events (odds ratio (OR) 0.43, 95% confidence interval (CI) 0.32 to 0.59; P < 0.00001) and total mortality (OR 0.57, 95% CI 0.42 to 0.78; P = 0.0004). Aspirin and dipyridamole reduced these events similarly. The risk of major bleeding was increased when antiplatelet agents were added to oral anticoagulants (OR 1.58, 95% CI 1.14 to 2.18; P = 0.006).For major bleeding, there was no evidence of heterogeneity between aspirin and dipyridamole and in the comparison of trials performed before and after 1990, around the time when anticoagulation standardisation with the international normalised ratio was being implemented. A lower daily dose of aspirin (< 100 mg) may be associated with a lower major bleeding risk than higher doses.

AUTHORS' CONCLUSIONS

Adding antiplatelet therapy, either dipyridamole or low-dose aspirin, to oral anticoagulation decreases the risk of systemic embolism or death among patients with prosthetic heart valves. The risk of major bleeding is increased with antiplatelet therapy. These results apply to patients with mechanical prosthetic valves or those with biological valves and indicators of high risk such as atrial fibrillation or prior thromboembolic events. The effectiveness and safety of low-dose aspirin (100 mg daily) appears to be similar to higher-dose aspirin and dipyridamole. In general, the quality of the included trials tended to be low, possibly reflecting the era when the majority of the trials were conducted (1970s and 1980s when trial methodology was less advanced).

Major bleeding risk in anticoagulated patients receiving concomitant antiplatelet therapy: a prospective study

INTRODUCTION

Current literature suggesting a higher bleeding risk during combination therapy compared to oral anticoagulation alone is primarily based on retrospective studies or specific populations. We aimed to prospectively evaluate whether unselected medical patients on oral anticoagulation have an increased risk of bleeding when on concomitant antiplatelet therapy.

MATERIAL AND METHODS

We prospectively studied consecutive adult medical patients who were discharged on oral anticoagulants between 01/2008 and 03/2009 from a Swiss university hospital. The primary outcome was the time to a first major bleed on oral anticoagulation within 12 months, adjusted for age, international normalized ratio target, number of medications, and history of myocardial infarction and major bleeding.

RESULTS

Among the 515 included anticoagulated patients, the incidence rate of a first major bleed was 8.2 per 100 patient-years. Overall, 161 patients (31.3%) were on both anticoagulant and antiplatelet therapy, and these patients had a similar incidence rate of major bleeding compared to patients on oral anticoagulation alone (7.6 vs. 8.4 per 100 patient-years, P=0.81). In a multivariate analysis, the association of concomitant antiplatelet therapy with the risk of major bleeding was not statistically significant (hazard ratio 0.89, 95% confidence interval, 0.37-2.10).

CONCLUSIONS

The risk of bleeding in patients receiving oral anticoagulants combined with antiplatelet therapy was similar to patients receiving oral anticoagulants alone, suggesting that the incremental bleeding risk of combination therapy might not be clinically significant.

Long-term mortality and morbidity after button Bentall operation

BACKGROUND AND AIM OF THE STUDY

The purpose of this study is to evaluate the long-term outcomes of the button Bentall procedure for the correction of aortic root disease.

METHODS

A total of 195 patients who underwent the button Bentall procedure between 1997 and 2010 were studied. The main pathology was annuloaortic ectasia. A mechanical valve was used in 163 patients (83.6%). The median duration of follow-up was 64 months (14133.0 patient-years).

RESULTS

There were five operative deaths (2.6%). Late overall mortality was 7.9%. The actuarial overall survival rate was 95.8 ± 1.5% at 5 years, 89.6 ± 3.4% at 10 years, and 75.9 ± 7.3% at 15 years. Multivariate logistic regression analysis identified preoperative poor mobility, cardiopulmonary bypass time, deep hypothermic circulatory arrest (DHCA) use, embolism, and bleeding event as significant independent risk factors for the late overall mortality. At 5, 10, and 15 years, actuarial composite valve graft-related event-free survival was 85.8 ± 2.8%, 75.5 ± 4.4%, and 69.3 ± 7.3%, respectively. Hypertension and concomitant coronary artery bypass graft (CABG) were independent predictors of composite valve graft-related events. Age, concomitant CABG, and DHCA use were associated with bleeding.

CONCLUSIONS

Valve-related morbidities, such as embolism and bleeding, determine the long-term overall mortality in aortic root replacement with button Bentall operation, similar to that in routine valve surgery.

Anticoagulation early after mechanical valve replacement: improved management with patient self-testing

OBJECTIVE

Self-testing to determine the international normalized ratio improves management with warfarin and reduces the risks of adverse events. Self-testing usually begins several weeks after hospital dismissal after valve replacement. We aimed to compare the in-hospital initiation of international normalized ratio self-testing with usual care in mechanical heart valve recipients.

METHODS

A total of 200 adult mechanical heart valve recipients were randomly assigned to in-hospital international normalized ratio self-testing instruction or usual care. Instruction for self-testing patients began on the fourth postoperative day. The patients were followed up for 3 months to compare the number of international normalized ratio tests, percentage of time in the therapeutic range, and adverse events.

RESULTS

The baseline characteristics were similar between the 2 groups. During the first 3 postoperative months, the usual-care group underwent an average of 10 international normalized ratio tests, and the self-testing group completed 14 international normalized ratio tests. The mean ± SD percentage of international normalized ratio tests within the therapeutic range was 45% ± 22% for the usual-care group and 52% ± 22% for the self-testing group (P = .05). Within 90 days after dismissal, transient ischemic attack occurred in 1 patient in the usual-care group and 2 patients in the self-testing group. Bleeding complications occurred in 3 patients in the usual-care group and 5 patients in the self-testing group.

CONCLUSIONS

Management of anticoagulation with warfarin after mechanical valve replacement is improved with self-testing, even during the early postoperative phase when international normalized ratio testing is performed frequently. Although the incidence of adverse events was similar in the 2 groups, better control of the international normalized ratio would be expected to improve outcome in large populations of patients.

Low-dose aspirin and cancer mortality: a meta-analysis of randomized trials

OBJECTIVE

Low-dose aspirin is a common strategy for preventing cardiovascular disease and associated mortality. A recent individual patient data meta-analysis of 8 trials of low- and high-dose aspirin, with long-term follow-up, found important reductions in cancer mortality. We aimed to determine whether cancer mortality also is reduced by low-dose aspirin in the shorter term.

METHODS

We conducted a comprehensive search of 10 electronic databases up to December 2011. We conducted a meta-analysis using data from all randomized clinical trials evaluating low-dose (75-325 mg) daily aspirin. We extracted data on non-cardiovascular disease mortality and cancer mortality. We pooled studies using a random-effects model and conducted a meta-regression. We supplemented this with a cumulative meta-analysis and trial sequential monitoring analysis.

RESULTS

Twenty-three randomized studies reported on nonvascular death. There were 944 nonvascular deaths of 41,398 (2.28%) patients receiving low-dose aspirin and 1074 nonvascular deaths of 41,470 (2.58%) patients not receiving aspirin therapy. The relative risk of nonvascular death was 0.88 (95% confidence interval [CI], 0.81-0.96, I(2) = 0%). Eleven trials included data evaluating cancer mortality involving 16,066 patients. There were 162 of 7998 (2.02%) and 210 of 8068 (2.60%) cancer deaths among low-dose aspirin users versus non-aspirin users, respectively, reported over an average follow-up of 2.8 years. The relative risk of cancer mortality was 0.77 (95% CI, 0.63-0.95, I(2) = 0%). Studies demonstrated a significant treatment effect after approximately 4 years of follow-up. The optimal information size analysis showed that a sufficient number of patients had been randomized to provide convincing evidence of a preventive role of low-dose aspirin in nonvascular deaths.

CONCLUSION

Nonvascular deaths, including cancer deaths, are reduced with low-dose aspirin.

Antithrombotic and thrombolytic therapy for valvular disease: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines

BACKGROUND

Antithrombotic therapy in valvular disease is important to mitigate thromboembolism, but the hemorrhagic risk imposed must be considered.

METHODS

The methods of this guideline follow those described in Methodology for the Development of Antithrombotic Therapy and Prevention of Thrombosis Guidelines. Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines in this supplement.

RESULTS

In rheumatic mitral disease, we recommend vitamin K antagonist (VKA) therapy when the left atrial diameter is > 55 mm (Grade 2C) or when complicated by left atrial thrombus (Grade 1A). In candidates for percutaneous mitral valvotomy with left atrial thrombus, we recommend VKA therapy until thrombus resolution, and we recommend abandoning valvotomy if the thrombus fails to resolve (Grade 1A). In patients with patent foramen ovale (PFO) and stroke or transient ischemic attack, we recommend initial aspirin therapy (Grade 1B) and suggest substitution of VKA if recurrence (Grade 2C). In patients with cryptogenic stroke and DVT and a PFO, we recommend VKA therapy for 3 months (Grade 1B) and consideration of PFO closure (Grade 2C). We recommend against the use of anticoagulant (Grade 1C) and antiplatelet therapy (Grade 1B) for native valve endocarditis. We suggest holding VKA therapy until the patient is stabilized without neurologic complications for infective endocarditis of a prosthetic valve (Grade 2C). In the first 3 months after bioprosthetic valve implantation, we recommend aspirin for aortic valves (Grade 2C), the addition of clopidogrel to aspirin if the aortic valve is transcatheter (Grade 2C), and VKA therapy with a target international normalized ratio (INR) of 2.5 for mitral valves (Grade 2C). After 3 months, we suggest aspirin therapy (Grade 2C). We recommend early bridging of mechanical valve patients to VKA therapy with unfractionated heparin (DVT dosing) or low-molecular-weight heparin (Grade 2C). We recommend long-term VKA therapy for all mechanical valves (Grade 1B): target INR 2.5 for aortic (Grade 1B) and 3.0 for mitral or double valve (Grade 2C). In patients with mechanical valves at low bleeding risk, we suggest the addition of low-dose aspirin (50-100 mg/d) (Grade 1B). In valve repair patients, we suggest aspirin therapy (Grade 2C). In patients with thrombosed prosthetic valve, we recommend fibrinolysis for right-sided valves and left-sided valves with thrombus area < 0.8 cm(2) (Grade 2C). For patients with left-sided prosthetic valve thrombosis and thrombus area ≥ 0.8 cm(2), we recommend early surgery (Grade 2C).

CONCLUSIONS

These antithrombotic guidelines provide recommendations based on the optimal balance of thrombotic and hemorrhagic risk.

Low doses of acetylsalicylic acid increase risk of gastrointestinal bleeding in a meta-analysis

BACKGROUND & AIMS

We performed a meta-analysis of data from randomized trials to estimate the risk of all-cause mortality and bleeding (and especially gastrointestinal [GI] bleeding) in patients treated with low doses of acetylsalicylic acid (ASA) (75-325 mg/d), alone or in combination with other medications.

METHODS

We searched 10 electronic databases (until October 2010) and collected data on adverse events in randomized controlled studies that evaluated low doses of ASA, alone (35 trials) or in combination with anticoagulants (18 trials), clopidogrel (5 trials), or proton pump inhibitors (PPIs; 3 trials). We analyzed data using random-effects meta-analysis and meta-regression, applying Peto's odds ratio (OR) for adverse events.

RESULTS

Low doses of ASA alone decreased the risk for all-cause mortality (relative risk, 0.93, 95% confidence interval [CI], 0.87-0.99), largely because of effects in secondary prevention populations. The risk of major GI bleeding increased with low doses of ASA alone (OR, 1.55; 95% CI, 1.27-1.90), compared with inert control reagents. The risk increased when ASA was combined with clopidogrel, compared with aspirin alone (OR, 1.86; 95% CI, 1.49-2.31), anticoagulants vs low doses of ASA alone (OR, 1.93; 95% CI, 1.42-2.61), or in studies that included patients with a history of GI bleeding or of longer duration. Importantly, PPI use reduced the risk for major GI bleeding in patients given low doses of ASA (OR, 0.34; 95% CI, 0.21-0.57).

CONCLUSIONS

In a meta-analysis, low doses of ASA increased the risk for GI bleeding; risk increased with accompanying use of clopidogrel and anticoagulant therapies, but decreased in patients who took PPIs.

Intracranial and fatal bleeding according to indication for long-term oral anticoagulant therapy

BACKGROUND

 Rate of major bleeding is generally accepted as a good measure of the risks associated with anticoagulant therapy, but this may not be true if the proportion of major bleeds with the most serious consequences differs according to the indication for anticoagulant therapy.

OBJECTIVE

To determine whether the indication for long-term oral anticoagulant therapy influences the proportion of major bleeds that are intracranial and fatal.

PATIENTS/METHODS

 Two authors abstracted intracranial and fatal bleeds from randomized trials of patients who received anticoagulant therapy for a minimum of 6months for atrial fibrillation, ischemic heart disease, venous thromboembolism, prosthetic heart valves and ischemic stroke.

RESULTS

There were 877 major bleeds among 23,518 patients in 39 studies. The proportion of bleeds that were intracranial was significantly higher in patients with ischemic stroke (36%; 95% CI, 22-52%; P=0.02) compared with patients with venous thromboembolism (10%; 95% CI, 5-20%). The difference in the proportion of bleeds that were intracranial among atrial fibrillation, ischemic heart disease, venous thromboembolism and prosthetic heart valves was not statistically significant; however, the estimates varied from 10% to 27%. The proportion of bleeds that were fatal did not differ significantly according to indication, but varied from 8% to 20%. For all indications for anticoagulation, intracranial bleeds were much more likely to be fatal than extracranial major bleeds (44% vs. 4% overall).

CONCLUSIONS

 In current practise, the indication for oral anticoagulant therapy has limited influence on the proportion of major bleeds that are intracranial or fatal.

Major hemorrhagic and thromboembolic complications in patients with mechanical heart valves receiving oral anticoagulant therapy

INTRODUCTION

Patients with mechanical heart valve prostheses are obligated to receive lifelong oral anticoagulant therapy to prevent thromboembolic complications; however, this treatment is associated with an increased risk of bleeding. The aim of this study was to evaluate the frequency of major hemorrhagic and thromboembolic complications in patients with mechanical heart valves who received oral anticoagulant therapy.

MATERIALS AND METHODS

The analysis involved 225 patients who underwent successful surgery in 2000; the mean (+/-SD) follow-up period was 43.3 +/- 9.2 months. Aortic, mitral, and double valve replacement was performed in 128 (56.7%), 70 (31.1%), and 27 (12.1%) of the patients, respectively. There were 128 men (57.3%), and the mean patient age was 57.9 +/- 18.8 years. The following data were assessed: rate of major hemorrhagic and thromboembolic complications, frequency of international normalized ratio (INR) rate measurements, and percentage of results within the therapeutic range.

RESULTS

Major hemorrhagic and thromboembolic complications occurred in 25 patients (11.1%). Seventeen patients (7.5%) survived, and 8 (3.6%) died of the complications. Major hemorrhagic and thromboembolic complications occurred in 17 patients (7.6%) and 8 patients (3.6%), respectively. The mean time between sequential measurements was 4.3 +/- 3.0 weeks, and of all the INR values collected, 42.4% were within, 31.3% were below, and 26.3% were above the target ranges.

CONCLUSIONS

Patients with a mechanical heart valve prosthesis receiving acenocoumarol are susceptible to major hemorrhagic and thromboembolic complications, some of which lead to death. Despite the danger related to these complications, patients receiving anticoagulant therapy still have difficulty achieving INR values within the therapeutic range.

Combined oral anticoagulants and antiplatelets: benefits and risks

Combined antiplatelet and anticoagulant therapy has been suggested for those clinical conditions in which conventional antithrombotic regimens have shown suboptimal efficacy, and in patients with indication for both: antiplatelet and anticoagulant therapy. Clinical trials aimed at assessing the clinical benefit of the association with respect to mono-therapy have been conducted in patients with atrial fibrillation, in patients with recent myocardial infarction, and in patients with prosthetic heart valves. Overall, a favorable benefit-risk profile of combined therapy in comparison to anticoagulant alone has been observed in patients with mechanical prosthetic heart valves and in those with coronary artery disease while no clear advantage has been shown in patients with atrial fibrillation. In almost all these studies, however, a higher risk of major bleeding has been observed in patients receiving combined therapy in comparison to patients receiving warfarin alone. Thus, a combined regimen of anticoagulant and antiplatelet therapy should be reserved for selected patients at high risk of thromboembolic events who have a low risk of bleeding.

Antithrombotic management of patients with prosthetic heart valves: current evidence and future trends

Over 4 million people worldwide have received a prosthetic heart valve, and an estimated 300,000 valves are being implanted every year. Prosthetic heart valves improve quality of life and survival of patients with severe valvular heart disease, but the need for antithrombotic therapy to prevent thrombotic complications in valve recipients poses challenges for clinicians and patients. Here, we review antithrombotic therapies for patients with prosthetic heart valves and management of thromboembolic complications. Advances in antithrombotic therapy and valve technologies are likely to improve the management of patients with prosthetic heart valves in developed countries, but the most important unmet need and potential for benefit from these new therapies is in developing countries where a massive and rapidly increasing burden of valvular heart disease exists.

Platelet reactivity in patients with a history of obstructive prosthetic valve thrombosis

One of the most serious complications of mechanical valves is obstructive prosthetic valve thrombosis (OPVT or "stuck valve"). Some patients develop OPVT despite an international normalized ratio (INR) in the therapeutic recommended range. We hypothesized that patients who develop OPVT have hyper-reactive platelets. We, therefore, examined platelet reactivity in patients who developed OPVT, despite a therapeutic or near-therapeutic INR, compared with a matched control group. We compared platelet reactivity between patients who had had an OPVT episode, despite a therapeutic or near-therapeutic INR (n = 18), and a matched group of patients with mechanical valves who did not develop this complication (n = 18) from 1996 to 2007. Platelet reactivity was evaluated by platelet aggregation in response to various agonists, platelet deposition under flow conditions in the Impact-R system, and plasma levels of platelet activation markers (soluble CD40 ligand and P-selectin). In the OPVT group, the average INR during the index episode was 3.1 +/- 1.5, and 44.6 +/- 40 months had elapsed from the index episode to the present study. Both groups were matched for gender, age +/-10 years, valve position and type, active smoking, and diabetes. Patients with an OPVT history had a greater aggregation in response to collagen (p = 0.05), greater platelet deposition in the Impact-R system (p = 0.01), and tended to have higher levels of soluble P-selection and soluble CD40 ligand (p = 0.07) than their control counterparts. In conclusion, patients with a history of OPVT appear to have increased platelet reactivity, which might contribute to an increased risk of thrombotic complications. These patients would, therefore, likely benefit from the addition of antiplatelet therapy to their standard anticoagulant treatment.

Clinical trials in heart valve disease

PURPOSE OF REVIEW

To summarize evidence from clinical trials of heart valve disease and identify areas where further trials are needed.

RECENT FINDINGS

Recent randomized studies suggest that statins do not influence progression of aortic stenosis. Other medical therapies with the potential to reduce progression of valve disease or decrease myocardial dysfunction include vasodilators in aortic regurgitation, angiotensin II receptor antagonists or beta-blockers in mitral regurgitation and angiotensin-converting enzyme inhibitors in aortic stenosis. However, these treatments have not been evaluated or have been evaluated only in small studies. Meta-analysis of randomized studies of antithrombotic strategies in patients with mechanical valves suggests overall risk is lower with the combination of warfarin with a lower target international normalized ratio and an antiplatelet drug. Novel anticoagulants have the potential to replace warfarin but have not yet been evaluated for this indication. Clinical trials are also needed to reliably evaluate different surgical strategies and novel percutaneous technology.

SUMMARY

Clinical trials in heart valve disease have important limitations, including the small number of trials undertaken and the small size of most studies. Many trials were undertaken more than 10-20 years ago in patients with earlier generation valve prostheses. To improve outcomes for patients with heart valve disease more clinical trials of contemporary approaches are needed.