Background: Cannabis use is increasing worldwide as legalization becomes more common. Prior studies have reported an association between cannabis use and increased risk of atrial fibrillation (AF). However, these have been cross-sectional and generally relied on diagnostic coding to identify cannabis users, which may not be representative of the typical recreational cannabis user. Goals: To examine the association between recreational cannabis use and AF risk. Methods: We utilized the UK Biobank, a prospective cohort study with serial assessments of lifestyle and medical diagnoses. Those who completed the cannabis use questionnaire and without prevalent AF were analyzed. Cannabis exposure was ascertained by self-reported lifetime use. AF events were identified using healthcare coding. Cox proportional hazard regression models were used to estimate the hazard ratios between the cannabis use groups and incident AF. Models were adjusted for age, sex, race, alcohol, coffee, smoking, education, and baseline cardiovascular comorbidities. Results: 157,305 participants (mean age 55.9 ± 7.7 years, 57.0% female, and 22.1% having used cannabis at least once) were followed for a mean 13.5 ± 1.7 years. Before multivariable adjustment, AF risk was found to be lower among occasional cannabis users (hazard ratio [HR] 0.71, 95% confidence interval [CI] 0.66 to 0.75, p < 0.001) and frequent cannabis users (HR 0.63, 95% CI 0.53 to 0.75, p < 0.001) compared to never users. However, after multivariable adjustment and compared to no cannabis use, neither occasional nor frequent cannabis use was associated with statistically significant differences in incident AF (HR 0.98, 95% CI 0.91 to 1.05, p = 0.58 and HR 0.98, 95% CI 0.82 to 1.18, p = 0.86 respectively) (Figure). Conclusions: Contrary to previous evidence relying on healthcare coding of cannabis use, this large prospective cohort study failed to reveal any evidence that cannabis use was associated with an increased risk of AF.

Importance Self-measured blood pressure (SMBP) with commercially available connected smartphone applications may help patients effectively use SMBP measurements. Objective To determine if enhanced SMBP paired with a connected smartphone application was superior to standard SMBP for blood pressure (BP) reduction or patient satisfaction. Design, Setting, and Participants This randomized clinical trial was conducted among 23 health systems participating in PCORnet, the National Patient-Centered Clinical Research Network, and included patients who reported having uncontrolled BP at their last clinic visit, a desire to lower their BP, and a smartphone. Enrollment and randomization occurred from August 3, 2019, to December 31, 2020, which was followed by 6 months of follow-up for each patient. Analysis commenced shortly thereafter. Interventions Eligible participants were randomly assigned to enhanced SMBP using a device that paired with a connected smartphone application (enhanced) or a standard device (standard). Participants received their device in the mail, along with web-based educational materials and phone-based support as needed. No clinician engagement was undertaken, and the study provided no special mechanisms for delivering measurements to clinicians for use in BP management. Main Outcomes and Measures Reduction in systolic BP, defined as the difference between clinic BP at baseline and the most recent clinic BP extracted from electronic health records at 6 months. Results Enrolled participants (1051 enhanced [50.0%] vs 1050 standard [50.0%]; 1191 women [56.7%]) were mostly middle-aged or older (mean [SD] age, 58 [13] years), nearly a third were Black or Hispanic (645 [31%]), and most were relatively comfortable using technology (mean [SD], 4.1 [1.1] of 5). The mean (SD) change in systolic BP from baseline to 6 months was -10.8 (18) mm Hg vs -10.6 (18) mm Hg (enhanced vs standard: adjusted difference, -0.19 mm Hg; 95% CI, -1.83 to 1.44; P = .81). Secondary outcomes were mostly null, except for documented attainment of BP control to lower than 140/<90 mm Hg, which occurred in 32% enhanced vs 29% standard groups (odds ratio, 1.15; 95% CI, 1.01-1.34). Most participants were very likely to recommend their SMBP device to a friend (70% vs 69%). Conclusions and Relevance This randomized clinical trial found that enhanced SMBP paired with a smartphone application is not superior to standard SMBP for BP reduction or patient satisfaction. Trial Registration ClinicalTrials.gov Identifier: NCT03796689.

The purpose of this study was to investigate the contribution of calcineurin-related intracellular signal for heat-stress-associated muscle hypertrophy. Wistar strain male rats (7-week-old) were randomly divided into four groups: (1) control (CC, n=15), (2) control with the injection of cyclosporine A (CsA) (CA, n=15), (3) heat-stressed (HC, n=15), and (4) heat-stressed with the injection of CsA (HA, n=15). The heat-stress groups (HC and HA) were exposed to heat (41°C for 60min) in a controlled heat chamber without anesthesia. Soleus and extensor digitorum longus (EDL) muscles were dissected and weighed 1, 7, and 14 days after the exposure. Wet and dry weights of soleus were increased 7 days following heat exposure. The expressions of heat shock protein 72 (HSP72) and calcineurin in both muscles were also increased within 1 and 7 days following heat-stress, respectively. Administration of CsA, a specific inhibitor for calcineurin, depressed heat-stress-associated increase of muscle weight and calcineurin expression, especially in soleus. These observations suggest that a calcineurin-dependent signaling pathway may play an important role in the heat-stress-related skeletal muscular hypertrophy. Application of heat-stress to skeletal muscles may be a useful tool to gain muscular mass and force generation not only in athletes, but also in patients during rehabilitation.