A retrospective analysis of anticoagulant safety among heart transplant recipients undergoing endomyocardial biopsy

BACKGROUND

Transvenous endomyocardial biopsy is an invasive procedure which is used to diagnose rejection following an orthotopic heart transplant. Endomyocardial biopsy is widely regarded as low risk with all-cause complication rates below 5% in most safety studies. Following transplant, some patients require therapeutic anticoagulation. It is unknown whether anticoagulation increases endomyocardial biopsy bleeding risk.

METHODS

Records from 2061 endomyocardial biopsies performed for post-transplant rejection surveillance at our institution between November 2016 and August 2022 were reviewed. Bleeding complications were defined as vascular access-related hematoma or bleeding, procedure-related red blood cell transfusion, and new pericardial effusion. Relative risk and small sample-adjusted 95% confidence interval was calculated to investigate the association between bleeding complications and anticoagulation.

RESULTS AND CONCLUSIONS

The overall risk of bleeding was 1.2% (25/2061 cases). There was a statistically significant increase in bleeding among patients on intravenous (RR 4.46, CI 1.09-18.32) but not oral anticoagulants (RR .62, CI .15-2.63) compared to patients without anticoagulant exposure. There was a trend toward increased bleeding among patients taking warfarin with INR ≥ 1.8 (RR 3.74, CI .90-15.43). Importantly, no bleeding events occurred in patients taking direct oral anticoagulants such as apixaban. Based on these results, intravenous rather than oral anticoagulation was associated with a significantly higher risk of bleeding complications following endomyocardial biopsy.

Maturation of Heterogeneity in Afferent Synapse Ultrastructure in the Mouse Cochlea

Auditory nerve fibers (ANFs) innervating the same inner hair cell (IHC) may have identical frequency tuning but different sound response properties. In cat and guinea pig, ANF response properties correlate with afferent synapse morphology and position on the IHC, suggesting a causal structure-function relationship. In mice, this relationship has not been fully characterized. Here we measured the emergence of synaptic morphological heterogeneities during maturation of the C57BL/6J mouse cochlea by comparing postnatal day 17 (p17, ∼3 days after hearing onset) with p34, when the mouse cochlea is mature. Using serial block face scanning electron microscopy and three-dimensional reconstruction we measured the size, shape, vesicle content, and position of 70 ribbon synapses from the mid-cochlea. Several features matured over late postnatal development. From p17 to p34, presynaptic densities (PDs) and post-synaptic densities (PSDs) became smaller on average (PDs: 0.75 to 0.33; PSDs: 0.58 to 0.31 μm²) and less round as their short axes shortened predominantly on the modiolar side, from 770 to 360 nm. Membrane-associated synaptic vesicles decreased in number from 53 to 30 per synapse from p17 to p34. Anatomical coupling, measured as PSD to ribbon distance, tightened predominantly on the pillar side. Ribbons became less spherical as long-axes lengthened only on the modiolar side of the IHC, from 372 to 541 nm. A decreasing gradient of synaptic ribbon size along the modiolar-pillar axis was detected only at p34 after aligning synapses of adjacent IHCs to a common reference frame (median volumes in nm³ × 10⁶: modiolar 4.87; pillar 2.38). The number of ribbon-associated synaptic vesicles scaled with ribbon size (range 67 to 346 per synapse at p34), thus acquiring a modiolar-pillar gradient at p34, but overall medians were similar at p17 (120) and p34 (127), like ribbon surface area (0.36 vs. 0.34 μm²). PD and PSD morphologies were tightly correlated to each other at individual synapses, more so at p34 than p17, but not to ribbon morphology. These observations suggest that PDs and PSDs mature according to different cues than ribbons, and that ribbon size may be more influenced by cues from the IHC than the surrounding tissue.

Randomized secondary prevention trial of azithromycin in patients with coronary artery disease and serological evidence for Chlamydia pneumoniae infection: The Azithromycin in Coronary Artery Disease: Elimination of Myocardial Infection with Chlamydia (ACADEMIC) study

BACKGROUND

Chlamydia pneumoniae commonly causes respiratory infection, is vasotropic, causes atherosclerosis in animal models, and has been found in human atheromas. Whether it plays a causal role in clinical coronary artery disease (CAD) and is amenable to antibiotic therapy is uncertain.

METHODS AND RESULTS

CAD patients (n=302) who had a seropositive reaction to C pneumoniae (IgG titers >/=1:16) were randomized to receive placebo or azithromycin, 500 mg/d for 3 days, then 500 mg/wk for 3 months. Circulating markers of inflammation (C-reactive protein [CRP], interleukin [IL]-1, IL-6, and tumor necrosis factor [TNF]-alpha), C pneumoniae antibody titers, and cardiovascular events were assessed at 3 and 6 months. Treatment groups were balanced, with age averaging 64 (SD=10) years; 89% of the patients were male. Azithromycin reduced a global rank sum score of the 4 inflammatory markers at 6 (but not 3) months (P=0. 011) as well as the mean global rank sum change score: 531 (SD=201) for active drug and 587 (SD=190) for placebo (P=0.027). Specifically, change-score ranks were significantly lower for CRP (P=0.011) and IL-6 (P=0.043). Antibody titers were unchanged, and number of clinical cardiovascular events at 6 months did not differ by therapy (9 for active drug, 7 for placebo). Azithromycin decreased infections requiring antibiotics (1 versus 12 at 3 months, P=0.002) but caused more mild, primarily gastrointestinal, adverse effects (36 versus 17, P=0.003).

CONCLUSIONS

In CAD patients positive for C pneumoniae antibodies, global tests of 4 markers of inflammation improved at 6 months with azithromycin. However, unlike another smaller study, no differences in antibody titers and clinical events were observed. Longer-term and larger studies of antichlamydial therapy are indicated.

Specimen type as a source of variability in the reproducibility and timing of cytomegalovirus identification by culture

Cytomegalovirus (CMV) is a significant contributor to morbidity and mortality among immunocompromised individuals; therefore, rapid and accurate diagnosis is essential. We compared positive cultures (n = 147) from different specimen types as to (a) the incubation time to a positive result and (b) the reproducibility of positive findings in replicate cultures. Five replicate shell vials were inoculated from each specimen: Two vials were stained at 24 h, two at 48 h, and one held and observed for a maximum of 30 days. Positive cultures from tissue biopsy specimens required the shortest incubation (mean = 1.9 days) and urine specimens the longest (mean = 3.9 days) (P < .005). Tissue biopsy specimens were the most reproducible (48.4% of specimens were positive in five of five replicates) and urine specimens the least (no specimens were positive in five of five replicate vials) (P < = .0002). The observed interspecimen variability is important because failure to understand and adjust for these differences could negatively influence the ability to identify CMV in culture.