Acquired thrombocytopenia after transcatheter aortic valve replacement: clinical correlates and association with outcomes.

AIMS: This study aimed to evaluate incidence and correlates for low platelet count after transcatheter aortic valve replacement (TAVR) and to determine a possible association between acquired thrombocytopenia and clinical outcomes. METHODS AND RESULTS: Patients undergoing TAVR from two medical centres were included in the study. They were stratified according to nadir platelet count post procedure: no/mild thrombocytopenia, ≥100 × 10(9)/L; moderate, 50-99 × 10(9)/L; and severe, <50 × 10(9)/L. A total of 488 patients composed of the study population (age 84.7 ± 7.5 years). At a median time of 2 days after TAVR, 176 patients (36.1%) developed significant thrombocytopenia: 149 (30.5%) moderate; 27 patients (5.5%) severe. Upon discharge, the vast majority of patients (90.2%) had no/mild thrombocytopenia. Nadir platelet count <50 × 10(9)/L was highly specific (96.3%), and a count <150 × 10(9)/L highly sensitive (91.2%), for predicting 30-day death (C-statistic 0.76). Patients with severe acquired thrombocytopenia had a significantly higher mortality rate at 1 year (66.7% for severe vs. 16.0% for no/mild vs. 20.1% for moderate; P < 0.001). In multivariate logistic regression, severe thrombocytopenia was independently associated with 1-year mortality (hazard ratio 3.44, CI: 1.02-11.6; P = 0.046). CONCLUSIONS: Acquired thrombocytopenia was common after TAVR and was mostly resolved at patient discharge. The severity of thrombocytopenia after TAVR could be used as an excellent, easily obtainable, marker for worse short- and long-term outcomes after the procedure.

Contrast sensitivity in pigeons: a comparison of behavioral and pattern ERG methods.

Contrast sensitivity (CS) is often used to assess spatial and temporal vision in animals. Conventional behavioral psychophysical techniques are both time and labor intensive, whereas measurement of CS functions by means of the pattern electroretinogram (PERG) is considerably more rapid and efficient. Are the two methods comparable, however? To answer this question, contrast-sensitivity functions were obtained using both the PERG and behavioral psychophysics in the same subjects, which were White Carneaux pigeons. The stimuli, in both methods, were phase-reversing, contrast-modulated sweeps of sinusoidal gratings. The PERG-CS functions were recorded via corneal electrodes and the behavioral data were collected using a modified staircase method that used moderate food deprivation and food reward. The results indicated that the PERG-CS functions had comparable bandwidth and peak spatial frequency to the behavioral CS functions. The PERG-CS functions, however, were lower on average than the behavioral curves by about 54%. The visual acuity of the two methods, as estimated from the high-frequency cutoff of the CS functions, differed by 37%. Both of these values are roughly consistent with the square root of 2 advantage of binocular viewing (behavioral method) over monocular viewing (PERG method). In addition, the peak spatial frequency showed a decrease of 0.125 c/deg with the PERG method and bandwidth was reduced by approximately 0.5 octave. These findings suggest that the PERG is an acceptable alternative to behavioral measurement of CS functions, especially in animal psychophysics, if one takes into account the underestimation of CS by the PERG method and the small changes in peak spatial frequency and bandwidth.