Dual versus single antiplatelet therapy after transcatheter aortic valve replacement: a systematic review and meta-analysis

Background

Transcatheter aortic valve replacement (TAVR) is the intervention of choice for patients with severe symptomatic aortic stenosis who have high or intermediate surgical risk. TAVR valves are at risk of thrombosis and serious sequelae including stroke, peripheral embolism, and valve dysfunction requiring intervention. The optimal method of antithrombotic therapy to reduce risk of thrombosis with an acceptable increase in risk of bleeding is uncertain.

Objectives

This systematic review and meta-analysis assesses the effects of dual antiplatelet therapy (DAPT) versus single antiplatelet therapy (SAPT) on mortality, thrombosis and bleeding in patients undergoing TAVR.

Methods

We systematically searched EMBASE, MEDLINE and CENTRAL from January 1, 2002 until February 9, 2021 for randomized trials comparing DAPT to SAPT after TAVR. Two reviewers independently screened titles and abstracts, and then the full text of potentially relevant articles in duplicate. Data abstraction and risk of bias was also performed in duplicate. Risk ratios and 95% confidence intervals were pooled using the Mantel-Haenzel method and random effects modelling. We assessed the certainty of the evidence for each outcome using the Grading of Recommendations, Assessments, Development and Evaluation (GRADE) approach.

Results

We included 4 randomized controlled trials of 1086 patients. Risk of bias was low or somewhat concerning for all studies. We found no difference in mortality (risk ratio (RR) 1.02, 95% confidence interval (CI), 0.63 to 1.63) or stroke (RR 1.03, 95% CI 0.57–1.84), but a significant increase in major bleeding (RR 2.04, 95% CI, 1.31–3.19), with DAPT compared to SAPT. There were too few events to conduct meta-analysis for clinical valve thrombosis, subclinical valve thrombosis, transvalvular gradients on echocardiography, or aortic valve reintervention. The certainty of the evidence was low or very low due to risk of bias, inconsistency, and imprecision.

Conclusions

There is very low certainty evidence that DAPT has little to no effect compared to SAPT on mortality and stroke. There is low certainty evidence that DAPT likely causes more major bleeding than SAPT.

Funding Acknowledgement

Type of funding sources: None.

VEGF induced hyperpermeability in bovine aortic endothelial cell and inhibitory effect of salvianolic acid B

AIM

To examine the effect of recombinant human vascular endothelial growth factor (VEGF) on the low density lipoprotein (LDL) permeability of bovine aortic endothelial cells (BAEC) and the inhibitory effect of salvianolic acid B in vitro.

METHODS

The confluence BAEC monolayers were cultured with normal medium and with medium containing VEGF or salvianolic acid B at various concentrations and for various time periods. The iodine labeled LDL flux across the monolayers was then performed, and radioactivity was measured by SN-695 automatic liquid scintillation counter.

RESULTS

Addition of purified human recombinant VEGF to the BAEC monolayers could significantly increase the permeability of the monolayer to 125I-LDL (P < 0.01). The permeability-increasing activity of VEGF on the BAEC monolayers was both dose and time dependent. Salvianolic acid B could markedly inhibit the VEGF-induced hyperpermeability in BAECs (P < 0.01).

CONCLUSION

VEGF plays a role in the formation and development of atherosclerosis, and salvianolic acid B has inhibitory effect on VEGF-induced hyperpermeability in BAEC.

Influence of insulin on follicular development and the intrafollicular insulin-like growth factor I (IGF-I) system in sows after weaning

Twenty-four crossbred primiparous sows were used to investigate the influence of insulin administration after weaning on the intrafollicular insulin-like growth factor i (IGF-I) system. Sows received 0.4 i.u. insulin kg-1 bodyweight or an equivalent volume of saline for 3 days (n = 5 insulin; n = 4 saline) or 5 days (n = 5 insulin; n = 6 saline) after weaning or served as untreated controls on day 1 (n = 4). The number and diameters of ovarian follicles were recorded, and fluid was aspirated from the 20 largest follicles for determination of oestradiol and IGF-I by radioimmunoassay and of insulin-like growth factor-binding proteins (IGFBPs) by western ligand blotting. The walls of the follicles were collected for mRNA analysis by RNase protection assay or granulosa cells were collected for estimation of apoptosis by flow cytometry. Insulin treatment resulted in smaller diameters of all follicles (P < 0.05) and tended (P < 0.07) to increase the number of follicles available on day 5 compared with saline-treated animals (19.8 versus 17.8). The concentration of oestradiol in follicular fluid from large (7-10 mm) follicles on days 3 and 5 was reduced (treatment by size class interaction; P < 0.05) by insulin treatment. Insulin also reduced intrafollicular concentrations of IGF-I at days 3 and 5 after weaning (treatment by day interaction; P < 0.02) while the amounts of IGFBP-3 and IGFBPs of molecular mass 30 and 22 kDa decreased from day 3 to day 5 in saline-treated animals only (treatment by day interaction; P < 0.05). Gene expression for IGF-I increased in saline-treated animals but decreased fourfold in insulin-treated sows from day 3 to day 5 (treatment by day interaction; P < 0.002). Gene expression for IGFBP-d decreased (P < 0.04) from day 3 to day 5, while expression of IGFBP-2 was unaffected by treatment or day. Overall, insulin influenced the IGF-I system in a manner consistent with slowing follicular growth and possibly allowed more follicles to become available for ovulation.

Fluid dynamics of venous valve closure

In vitro experiment was performed on a stented bovine jugular vein valve (VV, 14 mm I.D. x 2 cm long) and a stentless bovine jugular vein valve conduit (10 mm I.D. x 6 cm long) in a hydraulic flow loop with a downstream oscillatory pressure source to mimic respiratory changes. Simultaneous measurements were made on the valve opening area, conduit and sinus diameter changes using a specially designed laser optic system. Visualization of flow fields both proximal and distal to the venous valve, and the valve opening area were simultaneously recorded by using two video cameras. Laser Doppler anemometer surveys were made at three cross sections: the valve inlet, the valve exist, and 2 cm downstream of the venous valve to quantity flow reflux at valve closure. The experiment confirmed that the VV is a pressure-operated rather than a flow-driven device and that little or no reflux is needed to close the valve completely. The experiment further demonstrated that the VV sinus expands rapidly against back pressure, a critical character to consider in venous prosthesis design.

The change of carnitine content in seminal plasma after reversible injection occlusion of vas deferens

The change in carnitine content in seminal plasma after reversible injection occlusion of vas deferens (RIOVD) was observed. RIOVD is a safe, effective and simple method of male fertility control. Carnitine was determined by microenzymatic method. The incidence of sperm disappearance increased with the duration of RIOVD and reached 90% at the end of 12 months after operation. Before RIOVD, the mean value of carnitine in seminal plasma was 336.9 +/- 78.1 nmol/ml (X +/- SD, n = 58); after RIOVD, the mean value of seminal plasma carnitine was 112.7 +/- 50.7 nmol/ml (n = 172) in the group with sperm disappearance, and 172.5 +/- 71.7 nmol/ml (n = 51) in the group without sperm disappearance. There was a significant difference in carnitine content between pre-operation and postoperation (p < 0.01). After RIOVD, the carnitine concentration in seminal plasma of the group with sperm disappearance was lower than that of the group without sperm disappearance (p < 0.01). The results suggest that carnitine content in seminal plasma following RIOVD may be a reference index for judging the success or failure of the operation.