M icroRNAs (miRNAs) are small noncoding RNAs with cell-type specific expression patterns that are released by cells into the circulation as part of membranous particles or protein complexes.1 Thus, miRNAs can be readily quantified by real-time polymerase chain reactions (qPCRs) in plasma and serum and have generated increasing interest as potential new biomarkers.2 Our group has previously identified plateletrelated miRNA signatures that are predictive of cardiovascular events. 3 In addition, we measured miRNAs in healthy volunteers and in patients with symptomatic atherosclerosis before and after initiation of dual antiplatelet therapy and demonstrated reduced plasma levels of platelet-related miRNAs on platelet inhibition. Kaudewitz et al Plasma MicroRNAs and Platelet Function 421Dual oral antiplatelet therapy (acetylsalicylic acid [ASA]+a P2Y 12 inhibitor) is commonly used for the management of non-ST-segment-elevation acute coronary syndromes (ACS) and ST-segment-elevation myocardial infarction.5 ASA irreversibly inhibits cyclooxygenase 1 in platelets, thereby repressing thromboxane A 2 (TxA 2 ) synthesis and, consequently, platelet activation. Clopidogrel, prasugrel, and ticagrelor target the P2Y 12 receptor for ADP. However, interindividual variability in the platelet response to clopidogrel has been reported. Prasugrel and ticagrelor exhibit a more consistent antiplatelet effect and have shown benefits over clopidogrel in patients with ACS but also increase the risk of bleeding. 6,7 It is currently unclear whether plasma levels of platelet-related miRNAs correlate with the residual platelet activity in patients with ACS and how different antiplatelet agents alter miRNAs.In this study, we used RNA sequencing to characterize small RNAs in plasma. Then, we compared the effect of different antiplatelet agents and explored the association of small RNAs (miRNAs and YRNAs) with platelet function tests in patients with ACS. Moreover, we correlated their plasma levels to platelet activation markers in the prospective, population-based Bruneck study 3 and investigated whether a single-nucleotide polymorphism (SNP) that facilitates miR-126 processing 8 alters circulating miR-126 levels and platelet reactivity. These epidemiological observations were complemented by preclinical studies, assessing platelet function in mice on treatment with antagomiRs directed against miR-126 and by mechanistic studies measuring miR-126 targets. MethodsAn expanded Methods section is available in the Online Data Supplement. Next-Generation SequencingSmall RNA libraries were generated from non-normalized RNA (ranging from 375 pg to 1 ng) extracted from equal volumes of platelet-poor plasma (PPP) and platelet-rich plasma (PRP) from healthy human volunteers. Before library preparation, RNA was spiked with equal amounts of C. elegans miR-39 star (cel-miR-39*) to assist in normalization. Libraries were prepared using the small RNA library preparation kit version 2.0 (Illumina Cambridge Ltd) according to manufacturer's protocol with limi...

Over the last few years, several groups have evaluated the potential of microRNAs (miRNAs) as biomarkers for cardiometabolic disease. In this review, we discuss the emerging literature on the role of miRNAs and other small noncoding RNAs in platelets and in the circulation, and the potential use of miRNAs as biomarkers for platelet activation. Platelets are a major source of miRNAs, YRNAs, and circular RNAs. By harnessing multiomics approaches, we may gain valuable insights into their potential function. Because not all miRNAs are detectable in the circulation, we also created a gene ontology annotation for circulating miRNAs using the gene ontology term extracellular space as part of blood plasma. Finally, we share key insights for measuring circulating miRNAs. We propose ways to standardize miRNA measurements, in particular by using platelet-poor plasma to avoid confounding caused by residual platelets in plasma or by adding RNase inhibitors to serum to reduce degradation. This should enhance comparability of miRNA measurements across different cohorts. We provide recommendations for future miRNA biomarker studies, emphasizing the need for accurate interpretation within a biological and methodological context.

Background: YouTube is a highly utilized Web site that contains a large amount of medical educational material. Although some studies have assessed the education material contained on the Web site, little analysis of cardiology content has been made. This study aimed to assess the quality of videos relating to heart sounds and murmurs contained on YouTube. Hypothesis: We hypothesized that the quality of video files purporting to provide education on heart auscultation would be highly variable. Methods: Videos were searched for using the terms ''heart sounds,'' ''heart murmur,'' and ''heart auscultation.'' A built-in educational filter was employed, and manual rejection of non-English language and nonrelated videos was undertaken. Remaining videos were analyzed for content, and suitable videos were scored using a purpose-built tool. Results: YouTube search located 3350 videos in total, and of these, 22 were considered suitable for scoring. The average score was 4.07 out of 7 (standard deviation, 1.35). Six videos scored 5.5 or greater and 5 videos scoring 2.5 or less. There was no correlation between video score and YouTube indices of preference (hits, likes, dislikes, or search page). The quality of videos found in this study was highly variable. YouTube indications of preference were of no value in determining the value of video content. Therefore, teaching institutions or professional societies should endeavor to identify and highlight good online teaching resources. Conclusions: YouTube contains many videos relating to cardiac auscultation, but very few are valuable education resources.

Hypertension is associated with heightened cardiac sympathetic drive whilst statins reduce angiotensin II (ATII) signalling, superoxide anion production and increase nitric oxide bioavailability, events that can potentially reduce peripheral cardiac sympathetic neurotransmission. We therefore investigated whether pravastatin alters peripheral cardiac sympathetic control in the spontaneously hypertensive rat (SHR). SHRs (16–18 weeks) had significantly (p < 0.05) enhanced atrial 3H-norepinephrine (3H-NE) release to field stimulation compared to normotensive WKYs. 2-week pravastatin supplementation significantly reduced 3H-NE release to levels observed in the WKY. In-vivo, pravastatin lowered resting heart rate (HR) in the SHR despite not affecting arterial blood pressure or serum cholesterol. In SHR atria/right stellate ganglion preparations, the HR response to stellate stimulation (1, 3, and 5 Hz) was also significantly reduced by pravastatin whilst the HR response to exogenous NE (0.025–5 μmol) remained similar. The nitric oxide synthase (NOS) inhibitor l-NAME (1 mmol/l) increased 3H-NE release by similar amounts in atria from supplemented and non-supplemented SHRs, whilst Western blotting showed no difference in protein levels of nNOS, eNOS, guanylyl cyclase, or the NADPH oxidase subunits Gp91 and P40phox. Pravastatin significantly reduced cardiac ATII levels and angiotensin converting enzyme 1 and 2 expressions whilst protein levels of the ATII receptor (ATR1) remained unchanged in the SHR. Immunohistochemistry co-localised ATR1 with tyrosine hydroxylase positive neurons in the stellate ganglion. The ATR1 antagonist Losartan (5 μmol) equalised release of 3H-NE to comparable levels in supplemented and non-supplemented SHRs. These results suggest 2-week pravastatin treatment reduces cardiac ATII, and prevents its facilitatory effect on NE release thus normalising cardiac sympathetic hyper-responsiveness in SHRs.

A best evidence topic in cardiothoracic surgery was written according to a structured protocol. The question addressed was in adults with atrial fibrillation (AF), what preoperative size of left atrium impairs maze surgery success in terms of recurrence of AF. Altogether 422 papers were found using the reported search, of which 12 represented the best evidence to answer the clinical question. The authors, journal. date and country of publication, patient group studied, study type, relevant outcomes and results of these papers are tabulated. Nine of 12 papers found that preoperative left atrial (LA) size was significantly larger in patients who experienced recurrent AF. When left atrial diameter (LAD) was found to be statistically different between sinus conversion and recurrent AF groups the mean LAD was consistently >60 mm in the recurrent AF group, whereas it was <60 mm in all but one of the sinus conversion groups. In terms of a cut-off value for LA size, a left atrial volume index >135 ml/m(2) was found to confer 100% specificity for maze failure and a LAD >60 mm was found to be 100% sensitive for maze failure. A preoperative LAD <48.3 mm was shown in one study to be 100% sensitive for sinus conversion by the maze procedure. Despite much evidence highlighting preoperative LAD as a risk factor for maze failure, relatively few studies seek to define a definitive cut-off value for LA size beyond which the risks of the procedure (such as bleeding, infection or stroke) outweigh the chance of sinus recovery. We conclude that since mean preoperative LAD in AF groups is consistently over 60 mm caution should be exercised when offering these patients the maze procedure. Furthermore, the relationship between preoperative LAD and maze failure appears continuous and so patients should be counselled as to their increased risk of failure the further they deviate from a LAD of 60 mm. There is some evidence for and no available evidence to the contrary that a LAD < 43 mm is associated with complete maze success. Hence, these patients should be offered the maze procedure unless there are alternate strong contraindications.

YouTube contains a large volume of medical educational material. This study assessed the quality of respiratory auscultation videos contained in YouTube. Videos were searched for using the terms 'breath sounds', 'respiratory sounds', 'respiratory auscultation' and/or 'lung sounds'. In total, 6,022 videos were located, 36 of which were considered suitable for scoring for video accuracy, comprehensiveness and quality. The average score was 3.32/6 (55.3%±1.30). Video score correlated with time-adjusted YouTube metadata: hits per day (0.496, p=0.002) and likes per day (0.534, p=0.001). Video score also correlated with the fi rst search page on which the video was located in the 'breath sounds' and 'lung sounds' searches (-0.571, p=0.001; -0.445, p=0.014, respectively). The quality of videos was variable. Correlation between video score and some metadata values suggests that there is value for their use in judging video quality. However, the large number of videos found and inability to fi lter these results quickly makes locating educational content diffi cult.

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Re-expansion pulmonary oedema (REPO) is a rare complication of pleural fluid thoracocentesis and has been associated with a high mortality rate. There is limited evidence to inform on its most effective management. We present two cases of large volume thoracocentesis resulting in acute respiratory decompensation that was treated by reintroducing the drained pleural fluid back into the pleural cavity. We also present a review of the literature specifically assessing the reported incidence rate of REPO after pleural fluid drainage. In both of our cases, symptoms and signs of respiratory instability were promptly reversed on reintroduction of the drained pleural fluid into the patient's pleural space-a therapy we have termed 'rapid pleural space re-expansion'. This was not associated with any short-term adverse outcomes. The occurrence of REPO is a rare event with most cohort studies reporting an incidence of between 0% and 1%.