Citalopram is a more potent platelet function inhibitor than paroxetine in a case-control study

Neuroregeneration and Vascular Protection by Citalopram in Acute Ischemic Stroke (TALOS)

Background and Purpose- Recent studies indicate a possible beneficial effect on neuroregeneration and vascular protection of selective serotonin reuptake inhibitors after stroke. We conducted a national multicentre study to explore these effects. Methods- The TALOS study (The Efficacy of Citalopram Treatment in Acute Stroke) is a Danish placebo-controlled, randomized, double-blind study of citalopram started within 7 days after symptom onset to detect improvement in functional outcomes and cardiovascular protection in nondepressed, first-ever ischemic stroke. Study medication was given as add-on to standard medical care and treatment duration and follow-up was 6 months. There were 2 coprimary outcomes: changes in functional disability from 1 to 6 months on the modified Rankin Scale, and a composite vascular end point of transient ischemic attack/stroke, myocardial infarction, or vascular mortality during the first 6 months. Results- We enrolled 642 patients randomized to either citalopram (n=319) or placebo (n=323). Median National Institutes of Health Stroke Scale was 5.3 (range, 0-27) versus 4.8 (range, 0-28) at admission. Improvement in functional recovery from 1 to 6 months occurred in 160 (50%) patients on citalopram and 136 (42%) on placebo (odds ratio, 1.27; 95% CI, 0.92-1.74; P=0.057). When dropouts before 31 days were excluded (n=90), the analysis population showed an odds ratio of 1.37 (95% CI, 0.97-1.91; P=0.07). During a median follow-up of 150 days, 23 (7%) patients in the citalopram group and 26 (8%) patients in the placebo group had a primary, vascular end point (hazard ratio, 0.89; 95% CI, 0.50-1.60; P=0.24). A total of 28 patients (4%) died (16 versus 12; P=0.42) during the study. Conclusions- Early citalopram treatment did not improve functional recovery in nondepressed ischemic stroke patients within the first 6 months, although a borderline statistical significant effect was observed in the analysis population. The risk of cardiovascular events was similar between treatment groups, and citalopram treatment was well tolerated. Clinical Trial Registration- URL: https://www.clinicaltrials.gov . Unique identifier: NCT01937182. URL: https://www.clinicaltrialsregister.eu/ . EudraCT number: 2013-002253-30.

SSRI/SNRI Therapy is Associated With a Higher Risk of Gastrointestinal Bleeding in LVAD Patients

BACKGROUND

Gastrointestinal bleeding (GIB) is common in left ventricular assist device (LVAD) patients. Serotonin release from platelets promotes platelet aggregation, and selective serotonin reuptake inhibitor/serotonin-norepinephrine reuptake inhibitor (SSRI/SNRI) therapy inhibits the transporter responsible for re-uptake.

METHODS

We reviewed the records of LVAD (HeartMateII™, Abbott Medical, Lake Bluff, IL, USA and Heartware™, Medtronic, Minneapolis, MN, USA) patients at the Medical University of South Carolina and Johns Hopkins Hospital between January 2009 and January 2016. After exclusions, 248 patients were included for analysis. After univariate analysis, logistic regression multivariate analysis was performed to adjust for any demographic, cardiovascular, and laboratory data variables found to be associated with GI bleeding post-LVAD.

RESULTS

Gastrointestinal bleeding occurred in 85 patients (35%) with 55% of GIBs due to arteriovenous malformations (AVMs). Of the total cohort, 105 patients received an SSRI or SNRI during LVAD support. Forty-four (44) SSRI/SNRI (41.9%) and 41 non-SSRI/SNRI (28.7%) patients had a GIB (RR 1.46, p = 0.03). Twenty-six (26) (24.8%) of the SSRI/SNRI patients had a GIB due to AVMs versus 21 (14.7%) of the non-SSRI/SNRI patients (RR 1.69, p = 0.05). In fully-adjusted multivariate regression analysis, SSRI/SNRI therapy was independently associated with GIB (OR 1.78, p = 0.045). For GIB, the number needed to harm (NNH) was 7.6.

CONCLUSION

In conclusion, SSRI/SNRI therapy is independently associated with an increased risk of GIB in LVAD patients.

The Human Carbonic Anhydrase II in Platelets: An Underestimated Field of Its Activity

Carbonic anhydrases constitute a group of enzymes that catalyse reversible hydration of carbon dioxide leading to the formation of bicarbonate and proton. The platelet carbonic anhydrase II (CAII) was described for the first time in the '80s of the last century. Nevertheless, its direct role in platelet physiology and pathology still remains poorly understood. The modulation of platelet CAII action as a therapeutic approach holds promise as a novel strategy to reduce the impact of cardiovascular diseases. This short review paper summarises the current knowledge regarding the role of human CAII in regulating platelet function. The potential future directions considering this enzyme as a potential drug target and important pathophysiological chain in platelet-related disorders are described.

Baseline Platelet Activation and Reactivity in Patients with Critical Limb Ischemia

Background

Patients with critical limb ischemia (CLI) have a high risk to develop cardiovascular events (CVE). We hypothesized that in CLI patients platelets would display increased baseline activation and reactivity.

Objectives

We investigated baseline platelet activation and platelet reactivity in patients with CLI.

Patients/Methods

In this study baseline platelet activation and platelet reactivity in response to stimulation of all major platelet activation pathways were determined in 20 CLI patients (11 using aspirin and 9 using vitamin K-antagonists) included in the Juventas-trial (clinicaltrials.gov NCT00371371) and in 17 healthy controls. Platelet activation was quantified with flow cytometric measurement of platelet P-selectin expression and fibrinogen binding.

Results

CLI patients not using aspirin showed higher baseline platelet activation compared to healthy controls. Maximal reactivity to stimulation of the collagen and thrombin activation pathway was decreased in CLI patients compared to healthy controls. In line, attenuated platelet reactivity to stimulation of multiple activation pathways was associated with several traditional risk factors for cardiovascular disease.

Conclusions

Baseline platelet activation was increased in CLI patients, whereas the reactivity of circulating platelets to several stimulatory agents is decreased. Reactivity of platelets was inversely correlated with cardiovascular risk factors.

Major depression induces oxidative stress and platelet hyperaggregability

We have previously demonstrated an impairment of intraplatelet L-arginine-nitric oxide-cGMP pathway in major depression (MD) associated to platelet dysfunction. Here, we evaluated arginase pathway and phosphodiesterase 5 (PDE5) expression in platelets, systemic and intraplatelet oxidative status in untreated MD patients, and their effects on platelet aggregation. Blood samples were collected from 22 treatment naive MD patients (31 ± 2 yr) and 27 healthy subjects (33 ± 2 yr). MD patients presented with an activation of platelet arginase II, which competes with L-arginine for the production of nitric oxide (NO). An increase in protein carbonylation, overexpression of NADPH oxidase and PDE5, an enzyme that inactivates cGMP, was observed in platelets from MD patients compared to controls. In this context, platelet hyperaggregability was found in MD patients. On the other hand, antioxidant enzymes catalase, glutathione peroxidase and superoxide dismutase activities in serum and in platelets did not differ between groups. The increased activation of intraplatelet arginase and platelet aggregability, in addition to an overexpression of PDE5 and oxidative stress may contribute to alterations in L-arginine-NO-cGMP pathway and in platelet function, and consequently to the increased thrombotic risk in MD.

Increased platelet reactivity is associated with circulating platelet-monocyte complexes and macrophages in human atherosclerotic plaques

OBJECTIVE

Platelet reactivity, platelet binding to monocytes and monocyte infiltration play a detrimental role in atherosclerotic plaque progression. We investigated whether platelet reactivity was associated with levels of circulating platelet-monocyte complexes (PMCs) and macrophages in human atherosclerotic carotid plaques.

METHODS

Platelet reactivity was determined by measuring platelet P-selectin expression after platelet stimulation with increasing concentrations of adenosine diphosphate (ADP), in two independent cohorts: the Circulating Cells cohort (n = 244) and the Athero-Express cohort (n = 91). Levels of PMCs were assessed by flow cytometry in blood samples of patients who were scheduled for percutaneous coronary intervention (Circulating Cells cohort). Monocyte infiltration was semi-quantitatively determined by histological examination of atherosclerotic carotid plaques collected during carotid endarterectomy (Athero-Express cohort).

RESULTS

We found increased platelet reactivity in patients with high PMCs as compared to patients with low PMCs (median (interquartile range): 4153 (1585-11267) area under the curve (AUC) vs. 9633 (3580-21565) AUC, P<0.001). Also, we observed increased platelet reactivity in patients with high macrophage levels in atherosclerotic plaques as compared to patients with low macrophage levels in atherosclerotic plaques (mean ± SD; 8969 ± 3485 AUC vs. 7020 ± 3442 AUC, P = 0.02). All associations remained significant after adjustment for age, sex and use of drugs against platelet activation.

CONCLUSION

Platelet reactivity towards ADP is associated with levels of PMCs and macrophages in human atherosclerotic carotid plaques.

Platelet Activation Test in Unprocessed Blood (Pac-t-UB) to Monitor Platelet Concentrates and Whole Blood of Thrombocytopenic Patients

BACKGROUND

Platelet concentrate transfusion is the standard treatment for hemato-oncology patients to compensate for thrombocytopenia. We have developed a novel platelet activation test in anticoagulated unprocessed blood (pac-t-UB) to determine platelet function in platelet concentrates and in blood of thrombocytopenic patients.

METHODS

We have measured platelet activity in a platelet concentrate and in anticoagulated unprocessed blood of a post-transfusion thrombocytopenic patient.

RESULTS

Our data show time-dependent platelet activation by GPVI agonist (collagen related peptide; CRP), PAR-1 agonist (SFLLRN), P2Y12 agonist (ADP), and thromboxane receptor agonist (U46619) in a platelet concentrate. Furthermore, pac-t-UB showed time-dependent platelet activation in unprocessed blood of a post-transfusion patient with thrombocytopenia. Testing platelet function by different agonists in relation to storage show that 3-day-old platelet concentrates are still reactive to the studied agonists. This reactivity rapidly drops for each agonists during longer storage.

DISCUSSION

Pac-t-UB is a novel tool to estimate platelet function by different agonists in platelet concentrates and in unprocessed blood of thrombocytopenic patients. In the near future, we will validate whether pac-t-UB is an adequate test to monitor the quality of platelet concentrates and whether pac-t-UB predicts the bleeding risk of transfused thrombocytopenic patients.