Factors Associated with Coronary In-Stent Restenosis after Drug-Eluting Stent Implantation in Patients on Chronic Hemodialysis.

AIMS: Recently, drug-eluting stents (DESs) have been widely adopted for patients on chronic hemodialysis (HD). However, whether DES implantation is associated with a reduced rate of in-stent restenosis (ISR) is unclear. We investigated the incidence of ISR and its predictors in patients on HD after DES implantation. METHODS AND RESULTS: We analyzed 194 consecutive patients (331 lesions) on HD who underwent follow-up angiography after DES implantation. ISR was observed in 74 lesions (22.4%). Angiographically, the relative incidence of AHA/ACC type C lesion was increased (47 vs. 32%; p = 0.043), the minimal lumen diameter (MLD) before DES implantation was smaller (0.82 ± 0.49 vs. 0.97 ± 0.45 mm; p < 0.01), and the lesion length (LL) was increased (30.2 ± 16.1 vs. 24.4 ± 12.1 mm; p = 0.023) in lesions with ISR compared to those without ISR. The rate of rotational atherectomy use was also increased in lesions with ISR compared to those without ISR (50% vs. 25%; p < 0.01). In a multivariate analysis, the MLD before DES implantation (odds ratio [OR] = 0.50, 95% confidence interval [CI] 0.27-0.91, p = 0.024), LL (OR = 1.02, 95% CI 1.00-1.04, p = 0.030) and the use of rotational atherectomy (OR = 2.71, 95% CI 1.55-4.72, p < 0.01) were independent predictors of ISR. The incidence of ISR was similar between lesions treated with the first-generation (25.8%) and the second-generation DESs (20.4%). CONCLUSIONS: ISR was observed in 74 lesions (22.4%). A small MLD, long LL, and the use of rotational atherectomy were independent predictors of ISR after DES implantation in patients on HD. There was no significant difference in the ISR rate between the first- and the second-generation DESs.

Neural Correlates of Strategy Switching in the Macaque Orbital Prefrontal Cortex.

We can adapt flexibly to environment changes and search for the most appropriate rule to a context. The orbital prefrontal cortex (PFo) has been associated with decision making, rule generation and maintenance, and more generally has been considered important for behavioral flexibility. To better understand the neural mechanisms underlying the flexible behavior, we studied the ability to generate a switching signal in monkey PFo when a strategy is changed. In the strategy task, we used a visual cue to instruct two male rhesus monkeys either to repeat their most recent choice (i.e., stay strategy) or to change it (i.e., shift strategy). To identify the strategy switching-related signal, we compared nonswitch and switch trials, which cued the same or a different strategy from the previous trial, respectively. We found that the switching-related signal emerged during the cue presentation and it was combined with the strategy signal in a subpopulation of cells. Moreover, the error analysis showed that the activity of the switch-related cells reflected whether the monkeys erroneously switched or not the strategy, rather than what was required for that trial. The function of the switching signal could be to prompt the use of different strategies when older strategies are no longer appropriate, conferring the ability to adapt flexibly to environmental changes. In our task, the switching signal might contribute to the implementation of the strategy cued, overcoming potential interference effects from the strategy previously cued. Our results support the idea that ascribes to PFo an important role for behavioral flexibility.SIGNIFICANCE STATEMENT We can flexibly adapt our behavior to a changing environment. One of the prefrontal areas traditionally associated with the ability to adapt to new contingencies is the orbital prefrontal cortex (PFo). We analyzed the switching related activity using a strategy task in which two rhesus monkeys were instructed by a visual cue either to repeat or change their most recent choice, respectively using a stay or a shift strategy. We found that PFo neurons were modulated by the strategy switching signal, pointing to the importance of PFo in behavioral flexibility by generating control over the switching of strategies.

Late kidney injury after transcatheter aortic valve replacement.

BACKGROUND: Information on early to late-phase kidney damage in patients who underwent transcatheter aortic valve replacement (TAVR) is scarce. We aimed to identify the predictive factors for late kidney injury (LKI) at 1-year and patient prognosis beyond 1-year after TAVR. METHODS: We retrospectively reviewed 1,705 patients' data from the Japanese TAVR multicenter registry. Acute kidney injury (AKI) and LKI, defined as an increase of at least 0.3 mg/dL in creatinine level, a relative 50% decrease in kidney function from baseline to 48 hours and 1-year, were evaluated. The patients were categorized into the 4 groups as AKI-/LKI- (n = 1.362), AKI+/LKI- (n = 95), AKI-/LKI+ (n = 199), and AKI+/LKI+ (n = 46). RESULTS: The cumulative 3-year mortality rates were significantly increased across the four groups (12.5%, 15.8%, 24.6%, 25.8%, P < .001). Multivariate analysis revealed that chronic kidney disease, coronary artery disease, periprocedural AKI, and heart failure-related re-admission within 1-year were significantly associated with LKI. The Cox regression analysis revealed that AKI-/LKI+ and AKI+/LKI+ were independent predictors of increased late mortality beyond 1-year after TAVR (P = .001 and P = .01). CONCLUSIONS: LKI was influenced by adverse cardio-renal events and was associated with increased risks of late mortality beyond 1-year after TAVR.

The incidence, natural history, and predictive factors for tissue protrusion after drug-eluting stent implantation.

OBJECTIVES AND BACKGROUND: Although tissue protrusion (TP) between the stent struts after stent implantation has been implicate as a potential factor of stent failure, the incidence, natural history, and predictive factor of TP after stent implantation remains unclear. This prospective study evaluated the fate of TP after drug-eluting stent (DES) deployment using optical coherence tomography (OCT). METHOD AND RESULT: This study analyzed TP for 42 lesions after DES in which three serial OCTs, including preprocedure, postprocedure, and 1-month after the procedure were performed. TP was classified into the five groups: (a) persistent, (b) progressive, (c) healed, (d) regressive, and (e) late-acquired. Immediately after the procedure, 100 TPs in 37 lesions (88%) were identified. Of those, 53 (53%) were persistent, 3 (3%) were progressive, 20 (20%) were healed, and 24 (24%) were regressed at 1-month follow-up. Seven TPs in five patients (13%) were observed only at 1-month follow-up (late-acquired). CONCLUSION: In lesions with late-acquired TP, calcified nodule was identified as an underlying plaque morphology on preprocedural OCT. A serial OCT analysis found TP occurred not only immediately after DES implantation, but also 1-month after DES implantation.

Additional decrease in fractional flow reserve in the left anterior descending artery after hand-grip exercise during pharmacological coronary hyperemia.

Maximal hyperemia at the time of fractional flow reserve (FFR) measurement is generally induced by vasodilators, even when hyperemia at the onset of angina symptoms is caused by exercise stress. This study was designed to evaluate whether pharmacological hyperemia could be used as a substitute for exercise-induced hyperemia during FFR measurement. Twenty-two patients with angiographically intermediate stenosis in the left anterior descending artery (LAD) were prospectively enrolled. FFR measurements were repeated in the following two conditions while the pressure-wire was positioned in the same segment; (1) during pharmacological hyperemia induced by intracoronary administration of 2 mg nicorandil, (2) immediately after isotonic hand-grip exercise for 90 s (50% of maximum voluntary contraction) followed by intracoronary administration of 2 mg nicorandil. Isotonic hand-grip exercise increased systolic blood pressure (130 ± 19 versus 150 ± 22 mmHg, p < 0.001), heart rate (71 ± 11 versus 79 ± 13 bpm, p < 0.001), and cardiac output (5.1 ± 1.2 versus 5.9 ± 1.5 L/min, p < 0.001), which indicated an increased afterload on the left ventricle. After the hand-grip exercise, FFR significantly decreased from 0.86 ± 0.06 to 0.84 ± 0.06 (p < 0.001). A percent increase in systolic blood pressure and cardiac output after hand-grip exercise strongly correlated with ΔFFR (r = - 0.65, p < 0.001 and r = - 0.55, p < 0.001, respectively). An increase in cardiac output with hand-grip exercise during pharmacological hyperemia could induce an additional decrease in FFR for lesions located in the LAD.

Influence of different physiological hemodynamics on fractional flow reserve values in the left coronary artery and right coronary artery.

BACKGROUND: Although the left coronary artery (LCA) has a flow profile in that most blood flow occurs during diastole rather than systole, the right coronary artery (RCA) has a flow pattern that is less diastolic dominant. This study assessed whether coronary pressure waveforms distal to stenoses with the same fractional flow reserve (FFR) was the same between the LCA and RCA. METHODS: A total of 347 vessels from 318 patients who underwent FFR measurements were included. Conventional FFR was calculated as the ratio of the mean coronary distal pressure (Pd) to the mean aortic pressure (Pa) at maximal hyperemia. The pressure drop ratios in systole (PDRsystole) and diastole (PDRdiastole) were calculated as the sum of (Pa minus Pd) divided by the sum of Pa at the intracoronary diastolic and systolic pressure phases, respectively. RESULTS: Analysis of covariance of the regression line of correlation between conventional FFR and PDRsystole revealed that the slope was significantly greater in the RCA than in the left anterior descending artery (LAD) and left circumflex artery (LCX) (-0.765, -0.578, and -0.589, p < 0.001). On the other hand, the regression line of correlation between conventional FFR and PDRdiastole found that the slope was significantly greater in the LAD and LCX than in the RCA (-1.349, -1.318, and -1.223, p < 0.001). CONCLUSIONS: The pressure waveform distal to the stenosis differs between the LCA and RCA. In the LCA, the decrease in diastolic pressure mainly contributed to the drop in FFR, whereas in the RCA, it was the decrease in systolic pressure.

Prognostic impact and periprocedural complications of chronic steroid therapy in patients following transcatheter aortic valve replacement: Propensity-matched analysis from the Japanese OCEAN registry.

OBJECTIVE: This study aimed to assess the effect of chronic steroid use on periprocedural complications and clinical outcomes after transcatheter aortic valve replacement (TAVR). BACKGROUND: Chronic steroid use increases the risk of periprocedural complications and mortality during surgery. METHODS: We investigated 1,313 consecutive patients with aortic stenosis who underwent transfemoral (TF)-TAVR using data from a Japanese multicenter registry. The baseline characteristics, periprocedural complications including vascular complications (VCs), access route related VCs, and clinical outcomes were compared between patients in the steroid group and nonsteroid group. RESULTS: Major VCs and access route VCs occurred more in the steroid group than in the nonsteroid group (13.4 vs. 5.8%, p = .019; 20.9% vs. 9.8%, p = .004). Especially in the surgical cut-down group, the rate of access route VCs was differed between the two groups (28.0% vs. 7.5%, p = .003). The 30-day mortality rates were similar between the two groups (0% vs. 1.4%, p = .39). In the propensity score-matched model, the higher incidence of major VCs in the steroid group was maintained, although early mortality was similar in the two groups. CONCLUSIONS: Although chronic steroid therapy is not associated with increased early mortality, chronic steroid use may affect periprocedural VCs and access route VCs mainly due to surgical cut-down in patients following TF-TAVR.

Autocorrelation Structure in the Macaque Dorsolateral, But not Orbital or Polar, Prefrontal Cortex Predicts Response-Coding Strength in a Visually Cued Strategy Task.

In previous work, we studied the activity of neurons in the dorsolateral (PFdl), orbital (PFo), and polar (PFp) prefrontal cortex while monkeys performed a strategy task with 2 spatial goals. A cue instructed 1 of 2 strategies in each trial: stay with the previous goal or shift to the alternative goal. Each trial started with a fixation period, followed by a cue. Subsequently, a delay period was followed by a "go" signal that instructed the monkeys to choose one goal. After each choice, feedback was provided. In this study, we focused on the temporal receptive fields of the neurons, as measured by the decay in autocorrelation (time constant) during the fixation period, and examined the relationship with response and strategy coding. The temporal receptive field in PFdl correlated with the response-related but not with the strategy-related modulation in the delay and the feedback periods: neurons with longer time constants in PFdl tended to show stronger and more prolonged response coding. No such correlation was found in PFp or PFo. These findings demonstrate that the temporal specialization of neurons for temporally extended computations is predictive of response coding, and neurons in PFdl, but not PFp or PFo, develop such predictive properties.

Diastolic wall strain as a predictor of age-related cardiovascular events in patients with preserved left ventricular ejection fraction.

Diastolic wall strain (DWS) was reported as a simple and feasible echocardiographic index in assessing left ventricular (LV) diastolic stiffness. We sought to evaluate whether DWS predicts age-related cardiovascular events. Patients referred for transthoracic echocardiogram, those with preserved LV ejection fraction and no clinical heart failure were studied. Cardiovascular events were ascertained using Framingham criteria (myocardial infarction, coronary insufficiency, stroke, transient ischemic attack, congestive heart failure, or cardiovascular death). DWS was calculated with a validated formula. Cox proportional hazards modeling was used to assess the risk of cardiovascular events. Of a total number of 962 patients (mean age 60.9 ± 14.9 years, 48.0% men), 69 (7.2%) developed at least 1 cardiovascular event during a mean follow-up of 43 ± 32 months. After adjusting for cardiovascular comorbidities in a multivariable model, low DWS (≦ 0.33) was a significant independent predictor of cardiovascular events [hazard ratio (HR): 1.87, 95% confidential interval (CI) 1.04-3.36, P = 0.04]. Echocardiographic assessment of DWS may help in identifying the patients at increased risk for future age-related cardiovascular events.

Firing Variability of Frontal Pole Neurons during a Cued Strategy Task.

In previous reports, we described neuronal activity in the polar (PFp), dorsolateral (PFdl), and orbital (PFo) PFC as monkeys performed a cued strategy task with two spatial goals. On each trial, a cue instructed one of two strategies: Stay with the previous goal or shift to the alternative. A delay period followed each cue, and feedback followed each choice, also at a delay. Our initial analysis showed that the mean firing rate of a population of PFp cells encoded the goal chosen on a trial, but only near the time of feedback, not earlier in the trial. In contrast, PFdl cells encoded goals and strategies during the cue and delay periods, and PFo cells encoded strategies in those task periods. Both areas also signaled goals near feedback time. Here we analyzed trial-to-trial variability of neuronal firing, as measured by the Fano factor (FF): the ratio of variance to the mean. Goal-selective PFp neurons had two properties: (1) a lower FF from the beginning of the trial compared with PFp cells that did not encode goals and (2) a weak but significant inverse correlation between FF throughout a trial and the degree of goal selectivity at feedback time. Cells in PFdl and PFo showed neither of these properties. Our findings indicate that goal-selective PFp neurons were engaged in the task throughout a trial, although they only encoded goals near feedback time. Their lower FF could improve the ability of other cortical areas to decode its selected-goal signal.

Independent coding of absolute duration and distance magnitudes in the prefrontal cortex.

The estimation of space and time can interfere with each other, and neuroimaging studies have shown overlapping activation in the parietal and prefrontal cortical areas. We used duration and distance discrimination tasks to determine whether space and time share resources in prefrontal cortex (PF) neurons. Monkeys were required to report which of two stimuli, a red circle or blue square, presented sequentially, were longer and farther, respectively, in the duration and distance tasks. In a previous study, we showed that relative duration and distance are coded by different populations of neurons and that the only common representation is related to goal coding. Here, we examined the coding of absolute duration and distance. Our results support a model of independent coding of absolute duration and distance metrics by demonstrating that not only relative magnitude but also absolute magnitude are independently coded in the PF. NEW & NOTEWORTHY: Human behavioral studies have shown that spatial and duration judgments can interfere with each other. We investigated the neural representation of such magnitudes in the prefrontal cortex. We found that the two magnitudes are independently coded by prefrontal neurons. We suggest that the interference among magnitude judgments might depend on the goal rather than the perceptual resource sharing.

Context-Dependent Duration Signals in the Primate Prefrontal Cortex.

The activity of some prefrontal (PF) cortex neurons distinguishes short from long time intervals. Here, we examined whether this property reflected a general timing mechanism or one dependent on behavioral context. In one task, monkeys discriminated the relative duration of 2 stimuli; in the other, they discriminated the relative distance of 2 stimuli from a fixed reference point. Both tasks had a pre-cue period (interval 1) and a delay period (interval 2) with no discriminant stimulus. Interval 1 elapsed before the presentation of the first discriminant stimulus, and interval 2 began after that stimulus. Both intervals had durations of either 400 or 800 ms. Most PF neurons distinguished short from long durations in one task or interval, but not in the others. When neurons did signal something about duration for both intervals, they did so in an uncorrelated or weakly correlated manner. These results demonstrate a high degree of context dependency in PF time processing. The PF, therefore, does not appear to signal durations abstractedly, as would be expected of a general temporal encoder, but instead does so in a highly context-dependent manner, both within and between tasks.

Autonomous encoding of irrelevant goals and outcomes by prefrontal cortex neurons.

Two rhesus monkeys performed a distance discrimination task in which they reported whether a red square or a blue circle had appeared farther from a fixed reference point. Because a new pair of distances was chosen randomly on each trial, and because the monkeys had no opportunity to correct errors, no information from the previous trial was relevant to a current one. Nevertheless, many prefrontal cortex neurons encoded the outcome of the previous trial on current trials. A smaller, intermingled population of cells encoded the spatial goal on the previous trial or the features of the chosen stimuli, such as color or shape. The coding of previous outcomes and goals began at various times during a current trial, and it was selective in that prefrontal cells did not encode other information from the previous trial. The monitoring of previous goals and outcomes often contributes to problem solving, and it can support exploratory behavior. The present results show that such monitoring occurs autonomously and selectively, even when irrelevant to the task at hand.

Automatic comparison of stimulus durations in the primate prefrontal cortex: the neural basis of across-task interference.

Rhesus monkeys performed two tasks, both requiring a choice between a red square and a blue circle. In the duration task, the two stimuli appeared sequentially on each trial, for varying durations, and, later, during the choice phase of the task, the monkeys needed to choose the one that had lasted longer. In the matching-to-sample task, one of the two stimuli appeared twice as a sample, with durations matching those in the duration task, and the monkey needed to choose that stimulus during the choice phase. Although stimulus duration was irrelevant in the matching-to-sample task, the monkeys made twice as many errors when the second stimulus was shorter. This across-task interference supports an order-dependent model of the monkeys' choice and reveals something about their strategy in the duration task. The monkeys tended to choose the second stimulus when its duration exceeded the first and to choose the alternative stimulus otherwise. For the duration task, this strategy obviated the need to store stimulus-duration conjunctions for both stimuli, but it generated errors on the matching-to-sample task. We examined duration coding in prefrontal neurons and confirmed that a population of cells encoded relative duration during the matching-to-sample task, as expected from the order-dependent errors.

Neural representational geometries reflect behavioral differences in monkeys and recurrent neural networks.

Animals likely use a variety of strategies to solve laboratory tasks. Traditionally, combined analysis of behavioral and neural recording data across subjects employing different strategies may obscure important signals and give confusing results. Hence, it is essential to develop techniques that can infer strategy at the single-subject level. We analyzed an experiment in which two male monkeys performed a visually cued rule-based task. The analysis of their performance shows no indication that they used a different strategy. However, when we examined the geometry of stimulus representations in the state space of the neural activities recorded in dorsolateral prefrontal cortex, we found striking differences between the two monkeys. Our purely neural results induced us to reanalyze the behavior. The new analysis showed that the differences in representational geometry are associated with differences in the reaction times, revealing behavioral differences we were unaware of. All these analyses suggest that the monkeys are using different strategies. Finally, using recurrent neural network models trained to perform the same task, we show that these strategies correlate with the amount of training, suggesting a possible explanation for the observed neural and behavioral differences.

Neuronal activity during a cued strategy task: comparison of dorsolateral, orbital, and polar prefrontal cortex.

We compared neuronal activity in the dorsolateral (PFdl), orbital (PFo), and polar (PFp) prefrontal cortex as monkeys performed three tasks. In two tasks, a cue instructed one of two strategies: stay with the previous response or shift to the alternative. Visual stimuli served as cues in one of these tasks; in the other, fluid rewards did so. In the third task, visuospatial cues instructed each response. A delay period followed each cue. As reported previously, PFdl encoded strategies (stay or shift) and responses (left or right) during the cue and delay periods, while PFo encoded strategies and PFp encoded neither strategies nor responses; during the feedback period, all three areas encoded responses, but not strategies. Four novel findings emerged from the present analysis. (1) The strategy encoded by PFdl and PFo cells during the cue and delay periods was modality specific. (2) The response encoded by PFdl cells was task and modality specific during the cue period, but during the delay and feedback periods it became task and modality general. (3) Although some PFdl and PFo cells responded to or anticipated rewards, we could rule out reward effects for most strategy- and response-related activity. (4) Immediately before feedback, only PFp signaled responses that were correct according to the cued strategy; after feedback, only PFo signaled the response that had been made, whether correct or incorrect. These signals support a role in generating responses by PFdl, assigning outcomes to choices by PFo, and assigning outcomes to cognitive processes by PFp.

Increased prefrontal oxygenation related to distractor-resistant working memory in children with attention-deficit/hyperactivity disorder (ADHD).

This study aimed at investigating the effect of distraction on working memory and its underlying neural mechanisms in children with attention-deficit/hyperactivity disorder (ADHD). To this end, we studied hemodynamic activity in the prefrontal cortex using near-infrared spectroscopy while 16 children with ADHD and 10 typically developing (TD) children performed a working memory task. This task had two conditions: one involved a distraction during the memory delay interval, whereas the other had no systematic distraction. The ADHD patients showed significantly poorer behavioral performance compared with the TD group, particularly under the distraction. The ADHD group exhibited significantly higher level of prefrontal activation than did TD children. The activity level was positively correlated with the severity of ADHD symptoms. These results suggest that the impairment in the inhibition of distraction is responsible for the working memory deficits observed in ADHD children. Inefficient processing in the prefrontal cortex appears to underlie such deficits.

[Incidence and clinical outcome of contrast-induced nephropathy in the elderly patients].

BACKGROUND: Aging is an established risk factor for contrast-induced nephropathy (CIN). However, little information is available on the incidence and clinical outcome of CIN for the elderly patients in Japan. OBJECTIVES: We determined the incidence and clinical outcome of CIN in the Japanese elderly patient. METHODS: We studied 292 patients who had mild renal dysfunction (estimated glomerular filtration rate (eGFR) <60 ml/min/1.73 m(2)) at baseline and underwent coronary angiography. Patients were divided into two groups base on their age: the elderly group (age ≥ 75, n=108) and the control group (age<75, n=184). CIN was defined as a 25% increase in serum creatinine or an increase in serum creatinine by>0.5 mg/dl above the baseline value at or within 2 days post procedure. RESULTS: Patients in the elderly group had a higher incidence of CIN (14%) than those in the control group (9%). In patients who developed CIN, there was no significant difference between the two groups in baseline GFR and GFR on days 1, 2, 7 and 30 after the procedure. However, the relative increase in GFR above baseline on day 7 (-4.0 ± 6.1 vs -8.3 ± 8.0 ml/min P=0.096) and day 30 (1.5 ± 9.4 vs -10.1 ± 9.6 ml/min P=0.0017) in the elderly group was higher than that in the control group. Furthermore, death occurred in 3 patients in the elderly group (20%) whereas no patient died in the control group (P=0.092). CONCLUSION: Aging (age ≥ 75) is a risk factor for CIN in Japanese. CIN in the elderly patients may be associated with prolonged renal dysfunction and poor prognosis.

Comparison of strategy signals in the dorsolateral and orbital prefrontal cortex.

Abstract behavior-guiding rules and strategies allow monkeys to avoid errors in rarely encountered situations. In the present study, we contrasted strategy-related neuronal activity in the dorsolateral prefrontal cortex (PFdl) and the orbital prefrontal cortex (PFo) of rhesus monkeys. On each trial of their behavioral task, the monkeys responded to a foveal visual cue by making a saccade to one of two spatial targets. One response required a leftward saccade, the other required a saccade of equal magnitude to the right. The cues instructed the monkeys to follow one of two response strategies: to stay with their most recent successful response or to shift to the alternative response. Neurons in both areas encoded the stay and shift strategies after the cue appeared, but there were three major differences between the PFo and the PFdl: (1) many strategy-encoding cells in PFdl also encoded the response (left or right), but few, if any, PFo cells did so; (2) strategy selectivity appeared earlier in PFo than in PFdl; and (3) on error trials, PFo neurons encoded the correct strategy-the one that had been cued but not implemented-whereas in PFdl the strategy signals were weak or absent on error trials. These findings indicate that PFo and PFdl both contribute to behaviors guided by abstract response strategies, but do so differently, with PFo encoding a strategy and PFdl encoding a response based on a strategy.