Early antithrombotic therapy for aortic valve bioprostheses: is there an indication for routine use?

Benefit of Anticoagulation Early After Surgical Aortic Valve Replacement Using Bioprosthetic Valves

OBJECTIVE

To compare all-cause mortality and thromboembolic events in patients undergoing surgical aortic valve replacement (sAVR) receiving anticoagulation with warfarin versus patients with no systemic anticoagulation.

PATIENTS AND METHODS

Using data from the OptumLabs Data Warehouse, we investigated adult patients having bioprosthetic sAVR with or without coronary artery bypass from January 1, 2007, through December 31, 2019. Patients were classified into groups of nonwarfarin or warfarin (≥30 days of continuous prescription coverage after sAVR). One-to-one propensity score (PS) matching was used to adjust for group differences.

RESULTS

Of 10,589 patients having sAVR, 7659 (72.3%) were in the nonwarfarin group and 2930 (27.7%) were in the warfarin group. After PS matching, 2930 pairs of patients were analyzed. Median follow-up was 4.1 months (interquartile range [IQR], 2.6-7.4 months) for the warfarin group and 21.3 months (IQR, 7.8-24.0 months) for the nonwarfarin group. Overall mortality was lower for the warfarin group than for the nonwarfarin group (hazard ratio [HR], 0.68; 95% confidence interval [CI], 0.47 to 1.00; P=.047), and there was a trend toward decreased cumulative incidence of thromboembolic events (subdistribution HR [SHR], 0.62; 95% CI, 0.35 to 1.07; P=.09). Cumulative incidence of major bleeding events was higher for the warfarin group vs the nonwarfarin group (SHR, 1.94; 95% CI, 1.28 to 2.94; P=.002). Results were similar in a subgroup analysis of patients undergoing isolated sAVR.

CONCLUSION

During the prescription coverage period, warfarin use after bioprosthetic sAVR was associated with lower all-cause mortality and decreased risk of thromboembolism compared with not receiving warfarin. However, warfarin use was associated with an increased risk of major bleeding events.

Risks and benefits of concurrent treatment with antiplatelet and anticoagulation therapy in post-op bioprosthetic aortic valve replacement patients

BACKGROUND AND AIM

Among patients receiving surgical bioprosthetic aortic valve replacement (bAVR), there is an elevated risk of thromboembolic events postoperatively. However, the risks and benefits of varying anticoagulation strategies remain controversial. The aim of this study is to compare the risks and benefits of aspirin monotherapy to aspirin plus warfarin ("concurrent therapy") in patients receiving bAVR.

METHODS

A retrospective cohort study was conducted using patients' data from Kaiser Permanente Northern California, including those who underwent bAVR with or without coronary artery bypass grafting between 2009 and 2018. Patients were identified as having been discharged with aspirin only or concurrent therapy. The outcomes were mortality, thromboembolic events, and clinically relevant bleeding during a 6-month follow-up. The event rates were compared using the Kaplan-Meier method. Multivariable survival analysis, incorporating propensity scores, was used to estimate adjusted hazard ratios (aHRs) for each outcome.

RESULTS

The cohort consisted of 3047 patients. Approximately 58% of patients received aspirin only and 42% received concurrent therapy. Patients who received concurrent therapy were more likely to be older, have hypertension, previous stroke, and longer hospital stays. After adjustment using multivariable analysis, concurrent therapy was associated with a higher risk of clinically relevant bleeding (aHR, 2.33; 95% confidence interval, 1.67-3.25). There was no significant difference in the risk of thromboembolic events or mortality between the two groups.

CONCLUSION

Patients who underwent bAVR and were discharged on concurrent therapy compared to aspirin only had a significantly increased risk of bleeding without a significant difference in thromboembolic events.

Antithrombotic Strategies After Bioprosthetic Aortic Valve Replacement: A Systematic Review

BACKGROUND

The optimal antithrombotic regimen after bioprosthetic aortic valve replacement (bAVR) is unclear. We conducted a systematic review of various anticoagulation strategies following surgical or transcatheter bAVR (TAVR).

METHODS

We searched Medline, PubMed, Embase, Evidence-Based Medicine Reviews, and gray literature through June 2017 for controlled clinical trials and cohort studies that directly compared different antithrombotic strategies in nonpregnant adults who had undergone bAVR. We assessed risk of bias and graded the strength of the evidence using established methods.

RESULTS

Of 4,554 titles reviewed, 6 clinical trials and 13 cohort studies met inclusion criteria. We found moderate-strength evidence that mortality, thromboembolic events, and bleeding rates are similar between aspirin and warfarin after surgical bAVR. Observational data suggest lower mortality and thromboembolic events with aspirin combined with warfarin compared with aspirin alone after surgical bAVR, but the effect size is small and the combination is associated with a substantial increase in bleeding risk. We found insufficient evidence for all other treatment comparisons in surgical bAVR. In TAVR patients, we found moderate-strength evidence that mortality, stroke, and major cardiac events are similar between dual antiplatelet therapy and aspirin alone, though a nonsignificantly lower rate of bleeding occurred with aspirin alone.

CONCLUSIONS

Treatment with warfarin or aspirin leads to similar outcomes after surgical bAVR. Combining aspirin with warfarin may lead to a small decrease in thromboembolism and mortality, but is accompanied by increased bleeding. For TAVR patients, aspirin is equivalent to dual antiplatelet therapy for reducing thromboembolism and mortality, with a possible decrease in bleeding.

Oral anticoagulation, stroke and thromboembolism in patients with atrial fibrillation and valve bioprosthesis

Vitamin K antagonists are currently recommended in patients with ‘valvular’ atrial fibrillation (AF), e. g. those having mitral stenosis or artificial heart valves. We compared thromboembolic risk in patients with ‘non valvular’ AF and in those with AF and biological valve replacement (valve bioprosthesis). Among 8962 AF patients seen between 2000 and 2010, a diagnosis of ‘non-valvular AF’ was found in 8053 (94 %). Among patients with ‘valvular’ AF, 549 (6 %) had a biological prosthesis. The patients with bioprosthesis were older and had a higher CHA2DS2-VASc score than those with non valvular AF. After a follow-up of 876 é 1048 days (median 400 days, interquartile range 12–1483), the occurrence of thromboembolic events was similar in AF patients with bioprosthesis compared to those with ‘non valvular’ AF (hazard ratio [HR] 1.10 95 % confidence interval [CI] 0.83–1.45, p=0.52, adjusted HR 0.93, 95 %CI 0.68–1.25, p=0.61). Factors independently associated with increased risk of stroke/TE events were older age (HR 1.25, 95 %CI 1.16–1.34 per 10-year increase, p> 0.0001) and higher CHA2DS2-VASc score (HR 1.35, 95 %CI 1.24–1.46, p> 0.0001) whilst female gender (HR 0.75, 95 %CI 0.62–0.90, p=0.002), use of vitamin K antagonist (HR 0.83, 95 %CI 0.71–0.98, p=0.03) were independently associated with a lower risk of stroke/TE. Neither the presence of bioprosthesis nor the location of bioprosthesis was independent predictor for TE events. In conclusion, AF patients with bioprosthesis had a non-significantly higher risk of stroke/TE events compared to patients with non-valvular AF. Second, the CHA2DS2-VASc score was independently associated with an increased risk of TE events, and was a valuable determinant of TE risk both in AF patients with non-valvular AF as well as those with bioprosthesis, whether treated or not treated with OAC.

Note: The review process for this paper was fully handled by Christian Weber, Editor in Chief.

[Evaluation of the antithrombotic strategy in low thrombotic risk patients who underwent aortic valve replacement with a bioprosthesis]

According to current guidelines, in patients without additional risk factors who have undergone aortic valve replacement with a bioprosthesis, anticoagulation in the first 3 months after surgery is still a matter of debate. According to current evidence, aspirin in low doses is a reasonable alternative to vitamin K antagonists (VKA). A comparison is made between the incidence of thrombotic and haemorrhagic complications in patients with low thrombotic risk who underwent aortic valve replacement with a bioprosthesis in the National Institute of Cardiology of Ignacio Chávez of Mexico. The hypothesis: aspirin as monotherapy has a beneficial effect compared to VKA. The studied patients were the low thrombotic risk patients who underwent aortic valve replacement with a bioprosthesis in the National Institute of Cardiology of Ignacio Chávez of Mexico from 2011 to 2015. The groups studied were: aspirin only, VKA only, and the combination of VKA plus aspirin. The patients were retrospectively followed-up for 12 months, and the thrombotic and haemorrhagic complications were documented. Of the 231 patients included in the study, only one patient in the VKA only group presented with a haemorrhagic complication. No thrombotic complications were observed. In the present study no thrombotic complications were observed in patients who did not receive anticoagulation in the first 3 months after an aortic valve replacement with a bioprosthesis after a follow up period of 12 months. This suggests that the use of aspirin only is safe during this period.

Safety and Use of Anticoagulation After Aortic Valve Replacement With Bioprostheses: A Meta-Analysis

BACKGROUND

The American College of Cardiology guidelines recommend 3 months of anticoagulation after replacement of the aortic valve with a bioprosthesis. However, there remains great variability in the current clinical practice and conflicting results from clinical studies. To assist clinical decision making, we pooled the existing evidence to assess whether anticoagulation in the setting of a new bioprosthesis was associated with improved outcomes or greater risk of bleeding.

METHODS AND RESULTS

We searched the PubMed database from the inception of these databases until April 2015 to identify original studies (observational studies or clinical trials) that assessed anticoagulation with warfarin in comparison with either aspirin or no antiplatelet or anticoagulant therapy. We included the studies if their outcomes included thromboembolism or stroke/transient ischemic attacks and bleeding events. Quality assessment was performed in accordance with the Newland Ottawa Scale, and random effects analysis was used to pool the data from the available studies. I(2) testing was done to assess the heterogeneity of the included studies. After screening through 170 articles, a total of 13 studies (cases=6431; controls=18210) were included in the final analyses. The use of warfarin was associated with a significantly increased risk of overall bleeding (odds ratio, 1.96; 95% confidence interval, 1.25-3.08; P<0.0001) or bleeding risk at 3 months (odds ratio, 1.92; 95% confidence interval, 1.10-3.34; P<0.0001) compared with aspirin or placebo. With regard to composite primary outcome variables (risk of venous thromboembolism, stroke, or transient ischemic attack) at 3 months, no significant difference was seen with warfarin (odds ratio, 1.13; 95% confidence interval, 0.82-1.56; P=0.67). Moreover, anticoagulation was also not shown to improve outcomes at time interval >3 months (odds ratio, 1.12; 95% confidence interval, 0.80-1.58; P=0.79).

CONCLUSIONS

Contrary to the current guidelines, a meta-analysis of previous studies suggests that anticoagulation in the setting of an aortic bioprosthesis significantly increases bleeding risk without a favorable effect on thromboembolic events. Larger, randomized controlled studies should be performed to further guide this clinical practice.

Antithrombotic strategy in the three first months following bioprosthetic heart valve implantation

Heart valve prosthesis unquestionably improve quality of life and survival of patients with severe valvular heart disease, but the need for antithrombotic therapy to prevent thromboembolic complications is a major challenge to clinicians and their patients. Of the articles analyzed, most were retrospective series of cases or historical cohorts obtained from the database. The few published randomized trials showed no statistical power to assess the primary outcome of death or thromboembolic event. In this article, we decided to perform a systematic literature review, in an attempt to answer the following question: what is the best antithrombotic strategy in the first three months after bioprosthetic heart valve implantation (mitral and aortic)? After two reviewers applying the extraction criteria, we found 1968 references, selecting 31 references (excluding papers truncated, which combined bioprosthesis with mechanical prosthesis, or without follow-up). Based on this literature review, there was a low level of evidence for any antithrombotic therapeutic strategy evaluated. It´s therefore interesting to use aspirin 75 to 100 mg / day as antithrombotic strategy after bioprosthesis replacement in the aortic position, regardless of etiology, for patients without other risk factors such as atrial fibrillation or previous thromboembolic event. In the mitral position, the risk of embolism, although low, is more relevant than in the aortic position, according to published series and retrospective cohorts comprised mostly of elderly non-rheumatic patients.

Optimal thromboprophylaxis following bioprosthetic aortic valve replacement: still a matter of debate?

Optimal thromboprophylaxis following bioprosthetic aortic valve replacement (AVR) remains controversial. The main objective, which is the effective prevention of central nervous or peripheral embolic events, especially in the early postoperative period, will have to be weighed against the haemorrhagic risk that is associated with the utilization of different antithrombotic regimes. Most governing bodies in cardiovascular medicine have issued recommendations on thromboprophylaxis after the surgical implantation of aortic bioprostheses. However, the level of evidence to support these recommendations remains low, largely due to the inherent limitations of conducting appropriately randomized and adequately powered clinical research in this area. It is apparent from the recent surveys and large registries that there is a great variability in antithrombotic practice at an institutional or individual-clinician level reflecting this controversy and the lack of robust evidence. While organizational, financial or conceptual limitations could hinder the conduct and availability of conclusive research on optimal thromboprophylaxis after aortic bioprosthesis, it is imperative that all evidence is presented in a systematic way in order to assist the decision-making for the modern clinician. In this review, we provide an outline of the current recommendations for thromboprophylaxis, followed by a comprehensive and analytical presentation of all comparative studies examining anticoagulation vs. antiplatelet therapy after bioprosthetic AVR.

Clinical and prognostic implications of atrial fibrillation in patients undergoing transcatheter aortic valve implantation

AIM

To study a cohort of consecutive patients undergoing transcatheter aortic valve implantation (TAVI) and compare the outcomes of atrial fibrillation (AF) patients vs patients in sinus rhythm (SR).

METHODS

All consecutive patients undergoing TAVI in our hospital were included. The AF group comprised patients in AF at the time of TAVI or with history of AF, and were compared with the SR group. Procedural, echocardiographic and follow-up variables were compared. Likewise, the CHA(2)DS(2)-VASC stroke risk score and HAS-BLED bleeding risk score and antithrombotic treatment at discharge in AF patients were compared with that in SR patients.

RESULTS

From a total of 34 patients undergoing TAVI, 17 (50%) were allocated to the AF group, of whom 15 (88%) were under chronic oral anticoagulation. Patients in the AF group were similar to those in the SR group except for a trend (P = 0.07) for a higher logistic EuroSCORE (28% vs 19%), and a higher prevalence of hypertension (82% vs 53%) and chronic renal failure (17% vs 0%). Risk of both stroke and bleeding was high in the AF group (mean CHA(2)DS(2)-VASC 4.3, mean HAS-BLED 2.9). In the AF group, treatment at discharge included chronic oral anticoagulation in all except one case, and in association with an antiplatelet drug in 57% of patients. During a mean follow-up of 11 mo (maximum 32), there were only two strokes, none of them during the peri-procedural period: one in the AF group at 30 mo and one in the SR group at 3 mo. There were no statistical differences in procedural success, and clinical outcome (survival at 1 year 81% vs 74% in AF and SR groups, respectively, P = NS).

CONCLUSION

Patients in AF undergoing TAVI show a trend to a higher surgical risk. However, in our cohort, patients in AF did not have a higher stroke rate compared to the SR group, and the prognosis was similar in both groups.

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.

Anticoagulation or antiplatelet therapy of bioprosthetic heart valves recipients: an unresolved issue

Improvements in the performance and longevity of biological valve prostheses have steadily increased their rates of implantation in recent years. Aortic bioprostheses, which are commonly used in the elderly or when the risks of anticoagulating are high, have generally been associated with low rates of long-term complications. Freedom from anticoagulation, therefore, represents the main theoretical advantage of biological, compared with mechanical, aortic prostheses. While a variety of anticoagulant and antiplatelet drug regimens have been described, a precise antithrombotic protocol for the early postoperative period after bioprosthetic aortic valve replacement has not been developed. There are also important differences between the international guidelines published. This review examines the clinical evidence concerning the use of vitamin K antagonist and antiplatelet therapy in the early management of the antithrombotic complications after bioprosthetic aortic valve replacement.