Alterations in atrial electrogram amplitude as steady sinus rhythm transitions to paroxysmal atrial fibrillation during continuous monitoring in patients with implantable cardiac devices: Insights from the IMPACT study.

OBJECTIVES: We aimed to evaluate whether device measured amplitudes of atrial electrogram (AEGM) would change when measured in sinus rhythm (SR) transitioning to paroxysmal atrial fibrillation (AF) from previous steady SR, and significance of such change. METHODS: From the IMPACT trial's database we selected two groups; (A) those who developed AF (n = 164), and (B) propensity-matched control (n = 459) who stayed in SR during continuous Home Monitoring (HM) to compare AEGMs amplitudes at baseline SR and transition phase. RESULTS: During 420.0 ± 349.2 days (mean ± SD) from first postenrollment HM transmission to AF event transmission in Group A, and corresponding 515.3 ± 407.0 days in Group B, baseline and transition AEGM amplitude were 2.88 ± 1.146 and 2.74 ± 1.186 mV, respectively, for Group A (p = .1), and 2.88 ± 1.155 and 2.79 ± 1.145, respectively, for Group B (p < .005). Comparison of differences of AEGM amplitude, 0.14 ± 1.072 mV in Group A and 0.09 ± 0.893 mV in Group B were insignificant (p = .3). Age, sex, and hypertension identified as confounders had no association to AEGM changes (p = NS). CONCLUSIONS: Independent of age, sex, and hypertension, AEGMs amplitudes decline over a long period of time in patients with defibrillators and substrate for AF. The significance of such change remains unclear as it occurs whether patients develop AF or not, but raises a possibility of progressive atrial myopathy that patients with substrate for AF may be predisposed to.

Watching for Disease: the Changing Paradigm of Disease Screening in the Age of Consumer Health Devices.

There has been a recent proliferation of consumer health devices (CHDs) that enable user-initiated screening for a variety of diseases. These devices represent a paradigm shift in the deployment of disease screening, a process that has historically been led by clinicians following the guidance of professional bodies. The detection of AF via CHDs is a contemporary example of this phenomenon and highlights several important implications of the shift of disease screening from clinicians to CHD users. These include responsibility for patient data and outcomes, healthcare costs and access, and an evolution of the patient-provider relationship. However, as CHD technologies mature and become more affordable, they have the potential to detect actionable subclinical disease and improve health. Rather than allow CHDs to enter the marketplace organically with the potential for unintended negative consequences, it is critical that clinical, research, and industry communities proactively collaborate and establish best practices for their use.

The Effects of the Removal of Electronic Devices for 48 Hours on Sleep in Elite Judo Athletes.

This study examined the effects of evening use of electronic devices (i.e., smartphones, etc.) on sleep quality and next-day athletic and cognitive performance in elite judo athletes. Over 6 consecutive days and nights, 23 elite Australian judo athletes were monitored while attending a camp at the Australian Institute of Sport (AIS). In 14 athletes, all electronic devices were removed on days 3 and 4 (i.e., for 48 hours: the "device-restricted group"), whereas 9 were permitted to use their devices throughout the camp (the "control group"). All athletes wore an activity monitor (Readiband) continuously to provide measures of sleep quantity and quality. Other self-reported (diary) measures included time in bed, electronic device use, and rate of perceived exertion during training periods. Cognitive performance (Cogstate) and physical performance (single leg triple hop test) were also measured. When considering night 2 as a "baseline" for each group, removal of electronic devices on nights 3 and 4 (device-restricted group) resulted in no significant differences in any sleep-related measure between the groups. When comparing actigraphy-based measures of sleep to subjective measures, all athletes significantly overestimated sleep duration by 58 ± 85 minutes (p = 0.001) per night and underestimated time of sleep onset by 37 ± 72 minutes (p = 0.001) per night. No differences in physical or cognitive function were observed between the groups. CONCLUSION: This study has shown that the removal of electronic devices for a period of two nights (48 hours) during a judo camp does not affect sleep quality or quantity or influence athletic or cognitive performance.

Emergent reversal of vitamin K antagonists: addressing all the factors.

BACKGROUND: Reversal of warfarin-induced coagulopathy after traumatic injury may be done exclusively with prothrombin complex concentrates (PCCs). No direct comparisons between different PCC regimens exist to guide clinical decision-making. Our institution has used 2 distinct PCC strategies for warfarin reversal; a 3-Factor PCC (Profilnine) combined with activated Factor VII (3F-PCC+rVIIa), and a 4-Factor PCC (Kcentra) given without additional factor supplementation. METHODS: Retrospective review of all PCC administrations to trauma patients with acute bleeding who were taking warfarin before injury. Primary endpoints were international normalized ratio (INR) reduction, in-hospital mortality, and diagnosis of deep venous thrombosis (DVT). RESULTS: Eighty-seven patients were identified from 2011 to 2015. Fifty-three were treated with 3F-PCC+rVIIa and 34 with 4F-PCC. Patient demographics, injury severity, and presenting laboratory data were similar. The 3F-PCC+rVIIa produced a lower median (IQR) INR postreversal compared with 4F-PCC (.75 (.69, 1.00) vs 1.28 (1.13, 1.36), P<.001). Both regimens were able to obtain an INR lower than 1.5 immediately after administration (3F+rVIIA 93.9% vs 4F 97.1%, P =.51). In the 4F-PCC group, there was a significant decrease in the incidence of DVT (2.9% vs 22.6%), P < .01), and a nonsignificant reduction in mortality (2.9% vs 17.0%, P = .08). CONCLUSIONS: Use of 4F-PCC for warfarin reversal after traumatic hemorrhage is associated with a less severe decrease in INR, a significant reduction in DVT rates and a trend toward reduced mortality when compared with similar patients treated with 3F-PCC+rVIIa.

Nitrate supplementation and high-intensity performance in competitive cyclists.

Consumption of inorganic nitrate (NO3(-)) is known to enhance endurance exercise performance in recreationally trained subjects. Here we report the effect on a high-intensity performance task in national-level cyclists. The performance test consisted of 2 cycle ergometer time trials of 4 min duration with 75 min between trials. In a randomized crossover design, 26 cyclists performed the test under the following 4 conditions (each separated by a 6-day washout): consumption of 70 mL of nitrate-rich beetroot juice at 150 min or 75 min before the first time trial, addition of a 35 mL "top-up dose" following the first time trial in the 150 min condition, and consumption of a placebo. A linear mixed model with adjustments for learning effects and athlete fitness (peak incremental power) was used to estimate effects on mean power, with probabilistic inferences based on a smallest important effect of 1.0%. Peak plasma nitrite (NO2(-)) concentration was greatest when nitrate was taken 75 min before the first time trial. Relative to placebo, the mean effect of all 3 nitrate treatments was unclear in the first time trial (1.3%, 90% confidence limits: ±1.7%), but possibly harmful in the second time trial (-0.3%, ±1.6%). Differences between nitrate treatments were unclear, as was the estimate of any consistent individual response to the treatments. Allowing for sampling uncertainty, the effect of nitrate on performance was less than previous studies. Under the conditions of our experiment, nitrate supplementation may be ineffective in facilitating high-intensity exercise in competitive athletes.

Does hydrotherapy help or hinder adaptation to training in competitive cyclists?

PURPOSE: Cold water immersion (CWI) may be beneficial for acute recovery from exercise, but it may impair long-term performance by attenuating the stimuli responsible for adaptation to training. We compared effects of CWI and passive rest on cycling performance during a simulated cycling grand tour. METHODS: Thirty-four male endurance-trained competitive cyclists were randomized to CWI for four times per week for 15 min at 15°C or control (passive recovery) groups for 7 d of baseline training, 21 d of intensified training, and an 11-d taper. Criteria for completion of training and testing were satisfied by 10 cyclists in the CWI group (maximal aerobic power, 5.13 ± 0.21 W·kg; mean ± SD) and 11 in the control group (5.01 ± 0.41 W·kg). Each week, cyclists completed a high-intensity interval cycling test and two 4-min bouts separated by 30 min. CWI was performed four times per week for 15 min at 15°C. RESULTS: Between baseline and taper, cyclists in the CWI group had an unclear change in overall 4-min power relative to control (2.7% ± 5.7%), although mean power in the second effort relative to the first was likely higher for the CWI group relative to control (3.0% ± 3.8%). The change in 1-s maximum mean sprint power in the CWI group was likely beneficial compared with control (4.4% ± 4.2%). Differences between groups for the 10-min time trial were unclear (-0.4% ± 4.3%). CONCLUSION: Although some effects of CWI on performance were unclear, data from this study do not support recent speculation that CWI is detrimental to performance after increased training load in competitive cyclists.