Heart is composed of muscle cells called cardiomyocytes, including a specialized population, named pacemaker cells, that form the Cardiac Conduction System (CCS), responsible for generating the action potential dictating heart contractions. Failure of the CCS system leads to cardiac arrhythmias requiring complicated therapies and often surgical implantation of electrical pacemakers. However, recent research focusses on development of novel therapies using biological pacemakers aiming to substitute electrical devices. While most signalling pathways and transcription factors involved in the development of the pacemaker cells are known, the upstream regulatory networks need to be predicted through computer-based databases, mathematical modelling as well as functional testing of the regulatory elements in vivo, indicating the need for further research. Here we summarise the current knowledge about the vertebrate myocardial CCS system and development of the pacemaker cells and emphasise areas of future research to clarify the regulation of muscle pacemaker cells and ease development of biological therapies.

Background: This is a comparative analysis of upgrade to cardiac resynchronisation therapy (CRT) of an existing pacemaker implanted for bradyarrhythmia or an implantable cardioverter defibrillator (ICD). International guidelines recommend an upgrade to CRT for both groups based on the same criteria; this may lead to a hypothesis of whether we are under-treating a population that would otherwise benefit more from a CRT than the other. Methods: So far, this is the largest multicentre retrospective study that includes in total, 151 (93 upgrades to CRT-P and 58 upgrades to CRT-D) participants who had an upgrade to a CRT device between January 2010 and January 2020. Clinical and echocardiographic parameters were analysed both, before and after an upgrade to CRT. Results: EF was greater in patients with PPM, both before and after upgrade. Moreover, the post upgrade increase in EF was significantly greater in patients with PPM. Patients with ICD have, on average, an NYHA class ranking greater than PPM patients, both before and after upgrade. Conclusions: These data show that the PPM group patients have a greater response to upgrade to CRT compared to those from the ICD group. It also demonstrates that patients with non-ischaemic cardiomyopathy are better responders compared to those with ischaemic aetiology.

Drosophila circadian circuit is one of the best described neural circuits but is complex enough to obscure our understanding of how it actually works. Animals’ rhythmic behavior, the seemingly simple outcome of their internal clocks, relies on the interaction of heterogeneous clock neurons that are spread across the brain. Direct observations of their coordinated network interactions can bring us forward in understanding the circuit. The current challenge is to observe activity of each of these neurons over a long span of time –hours to days– in live animals. Here we review the progress in circadian circuit interrogation powered by in vivo calcium imaging.

Background: Gastrointestinal stromal tumors (GIST) are rare mesenchymal neoplasms of the gastrointestinal tract (GIT) that represent approximately 1 to 2 percent of primary gastrointestinal (GI) cancers. Owing to their rarity, very little is known about the overall epidemiology and prognostic factors of the pathology. The purpose of this study is to investigate the clinical characteristics, survival outcomes, and independent prognostic factors of patients with GIST in the past decade. Methods: A total of 2,374 patients diagnosed with GIST, between 2010 and 2017, were ultimately enrolled in our study by retrieving the Surveillance, Epidemiology, and End Results (SEER) database. We analyzed demographics, clinical characteristics, and overall mortality (OM) as well as cancer-specific mortality (CSM) of GIST. Variables with a p value < 0.01 in the univariate Cox regression were incorporated into the multivariate Cox model to determine the independent prognostic factors, with a hazard ratio (HR) of greater than 1 representing adverse prognostic factors. Results: Multivariate cox proportional hazard regression analyses of factors affecting all-cause mortality and GIST related mortality among US patients between 2010 and 2017 revealed higher overall mortality in Non-Hispanic Blacks (HR= 1.516, 95% CI 1.172-1.961, p= 0.002), age 80+ (HR= 9.783, 95% CI4.185-22.868, p= 0), followed by age 60-79 (HR= 3.408, 95% CI 1.488-7.807, p=0.004); male patients (HR= 1.795 , 95% CI 1.461-2.206, p=0); advanced disease with distant metastasis (HR= 3.865 , 95% CI 2.977-5.019, p=0), followed by regional involvement by both direct extension and lymph node involvement (HR= 3.853, 95% CI 1.551-9.57, p=0.004); and widowed patients (HR= 1.975, 95% CI 1.494-2.61, p= 0), followed by single patients (HR= 1.53, 95% CI 1.154-2.028, p=0.003). The highest CSM was observed in the same groups, except widowed patients and patients aged 60-79. The highest CSM was also observed among patients that underwent chemotherapy (HR= 1.687, 95% CI 1.19-2.392, p= 0.003). Conclusion: In this United States population-based retrospective cohort study using the SEER database, we found that non-Hispanic blacks, male patients, and patients older than 60 years have a higher mortality with GIST. Furthermore, patients who received chemotherapy have a higher GIST specific mortality and married patients had a lower mortality. However, we do not know to what extent these independent prognostic factors interact with each other to influence mortality. This study paves the way for future studies addressing those interactions. The results of this study may help treating clinicians to identify patient populations associated with dismal prognosis as those may require closer follow-up and more intensive therapy; furthermore, with married patients having a better survival, we hope to encourage clinicians to involve family members of the affected patients early in the disease course as the social support might impact the prognosis.

Cardiac amyloidosis is caused by amyloid fibrils that deposit in the myocardial interstitium, causing restrictive cardiomyopathy and eventually death. The electromechanical, inflammatory, and autonomic changes due to amyloid deposition result in arrhythmias. Atrial fibrillation is by far the most common arrhythmia. Rate control strategy is generally poorly tolerated due to restrictive filling physiology and heart rate dependance, favoring adoption of rhythm control strategy. Anticoagulation for stroke prophylaxis is warranted irrespective of CHA2DS2Vasc score in patients with favorable bleeding profile; data on left appendage closure devices is still insufficient. Ventricular arrhythmias are also not uncommon and the role of implantable cardioverter-defibrillator in cardiac amyloidosis is controversial. There is no evidence of improvement in outcomes when used for primary prevention in these patients. Bradyarrhythmia is most commonly associated with sudden cardiac death in cardiac amyloidosis. Pacemaker implantation can help provide symptomatic relief but does not confer mortality benefit.

Introduction: The aim of our study was to assess the role of ECG-gated Coronary CT Angiography (CCTA) in the diagnosis, imaging follow-up, and treatment guidance in post-procedural/surgical interventions of the heart and thoracic aorta (PTCA, TAVI, PMK/ICD placement, CABGs).