Inappropriate Underdosing of Direct Oral Anticoagulants in Atrial Fibrillation Patients: Results from the START2-AF Registry

Background: Direct oral anticoagulants (DOACs) are recommended for stroke prevention in non-valvular atrial fibrillation (NVAF) patients. We aimed to describe the prevalence of inappropriate DOACs dose prescription in the START2-AF Registry, the outcomes according to the appropriateness of the dosage, and the factors associated with inappropriate dose prescription. Methods: Patients' demographics and clinical data were prospectively collected as electronic files in an anonymous form on the website of the START2-Registry; DOACs dosage was determined to be appropriate when prescribed according to the European Heart Rhythm Association Guidelines. Results: We included 5943 NVAF patients on DOACs; 2572 (46.3%) were female patients. The standard dose (SD) was prescribed to 56.9% of patients and the low dose (LD) was prescribed to 43.1% of patients; 38.9% of all NVAF patients received an inappropriate LD DOAC and 0.3% received inappropriate SD. Patients treated with LD DOAC had a significantly higher rate of all bleedings (RR 1.5; 95% CI 1.2-2.0), major bleedings (RR 1.8; 95% CI 1.3-1.7), and mortality (RR 2.8; 95% CI 1.9-4.1) with respect to patients treated with SD DOAC. No difference was found among patients treated with appropriate and inappropriate LD regarding bleeding, thrombotic, and mortality rates. Age, body weight <60 kg, and renal failure were significantly associated with inappropriate LD DOAC prescription. Conclusions: Inappropriate LD DOACs in NVAF patients is not associated with a reduction in bleeding risk, nor with an increased thrombotic risk. Instead, it is associated with higher mortality rate, suggesting that, in clinical practice, underdosing is preferred for patients at particularly high risk for adverse events.

Risk of reoperation in bioprosthetic valve patients with indication for long-term anticoagulation. Results from the observational retrospective multicentre PLECTRUM study

Objective

Several factors should be considered when a prosthetic heart valve, bioprosthetic valve (BV) or mechanical valve is to be implanted: thrombogenicity, life expectancy and the risk of reoperation.

Methods

We conducted an observational retrospective multicentre study among Italian Thrombosis Centers on patients with BV on long-term vitamin K antagonist (VKA) treatment to evaluate the risk of reoperation and the rate of bleeding and thrombotic events.

Results

We analysed 612 patients (median age 71.8 years) with BV on long-term VKA treatment for the presence of atrial fibrillation (AF) (78.4%) or other indications (21.6%). Thirty-four major bleeding events (rate 1.1×100 patient-years) and 29 thromboembolic events (rate 0.9×100 patient-years) were recorded, and 46 patients (rate 1.5×100 patient-years) underwent reoperation. The rate of reoperation was higher among younger patients: 32.9% in patients <60 years and 3.9% in patients ≥60 years (relative risk (RR) 3.8, 95% CI 2.1 to 7.2; p=0.0001). When patients were analysed according to age <65 or ≥65 years and <75 or ≥70 years, younger patients still were at higher risk for reoperation (RR 3.1, 95% CI 1.7 to 6.0 and 3.7, 95% CI 1.7 to 8.6, respectively).

Conclusions

Our findings suggest that the threshold of 65 years for implanting a BV should be carefully evaluated, considering the high risk for reoperation and the high risk of AF occurrence with persisting need for long-term anticoagulation. The high risk for reoperation of young patients implanted with BV and the availability of a safer and easier way to conduct VKA treatment, such as the use of point-of-care devices, should be considered when the type of valve must be chosen.

[Normal values of carboxyhemoglobinemia and methemoglobinemia in a sample of conscripts]

Carboxyhemoglobin (COHb) and methemoglobin (MetHb) values in blood were measured in a population of 296 asymptomatic conscripts who were not under medical treatment and had no occupational exposure. The mean COHb value was 3.25 (S.D. = 1.45%) in smokers and 1.34 (S.D. = 0.8) in non-smokers, with a wide variability in both subgroups, particularly among smokers. The COHb levels in moderate smokers were lower than in heavy smokers, but smoking just before the blood test greatly increased the COHb levels. Non-smoking country dwellers had lower COHb levels than non-smoking city dwellers, but the COHb levels of smokers were independent of residence and were only smoking-related. The sample MetHb level was 0.81 (S.D. = 0.37) and was influenced by country living and smoking. Levels were lowest in non-smoking country dwellers (0.66, S.D. = 0.38%) and increased with moderate smoking (0.71, S.D. = 0.40%). Heavy smoker levels were independent of residence. Smoking just before the blood test had no effect on the value.

Insulin receptors in children's erythrocytes. Study on aging cells

Aim of this study was to evaluate the influence of the red cell aging process on insulin receptor binding. In erythrocytes from 8 children with high reticulocyte count and 9 healthy age-matched subjects we studied insulin receptor binding in correlation with pyruvate kinase (PK) activity and creatine levels. Moreover maximum 125I-insulin bound % and PK activity were tested in four red cell fractions of different age. Our data show a significant correlation between 125I-insulin bound and either PK activity or creatine levels. In vitro experiments on red cell fractions of different age (as tested by creatine levels) evidence a lower decay of PK activity than insulin bound (p less than 0.05). Our results indicate that creatine content is the best marker of red cell age for insulin receptor studies.