Background Cardiac muscle hypercontractility is a key pathophysiological abnormality in hypertrophic cardiomyopathy, and a major determinant of dynamic left ventricular outflow tract (LVOT) obstruction. Available pharmacological options for hypertrophic cardiomyopathy are inadequate or poorly tolerated and are not disease-specific. We aimed to assess the efficacy and safety of mavacamten, a first-in-class cardiac myosin inhibitor, in symptomatic obstructive hypertrophic cardiomyopathy. Methods In this phase 3, randomised, double-blind, placebo-controlled trial (EXPLORER-HCM) in 68 clinical cardiovascular centres in 13 countries, patients with hypertrophic cardiomyopathy with an LVOT gradient of 50 mm Hg or greater and New York Heart Association (NYHA) class II-III symptoms were assigned (1:1) to receive mavacamten (starting at 5 mg) or placebo for 30 weeks. Visits for assessment of patient status occurred every 2-4 weeks. Serial evaluations included echocardiogram, electrocardiogram, and blood collection for laboratory tests and mavacamten plasma concentration. The primary endpoint was a 1•5 mL/kg per min or greater increase in peak oxygen consumption (pVO 2) and at least one NYHA class reduction or a 3•0 mL/kg per min or greater pVO 2 increase without NYHA class worsening. Secondary endpoints assessed changes in post-exercise LVOT gradient, pVO 2 , NYHA class, Kansas City Cardiomyopathy Questionnaire-Clinical Summary Score (KCCQ-CSS), and Hypertrophic Cardiomyopathy Symptom Questionnaire Shortness-of-Breath subscore (HCMSQ-SoB). This study is registered with ClinicalTrials.gov, NCT03470545.

Both autonomic nerve activity and electrical remodeling are important in atrial arrhythmogenesis. Therefore, dogs with sympathetic hyperinnervation, myocardial infarction (MI), and complete atrioventricular block (CAVB) may have a high incidence of atrial arrhythmias. We studied eight dogs (experimental group) with MI, CAVB, and sympathetic hyperinnervation induced either by nerve growth factor infusion (n = 4 dogs) or subthreshold electrical stimulation (n = 4 dogs) of the left stellate ganglion. Cardiac rhythm was continuously monitored by a Data Sciences International transmitter for 48 (SD 27) days. Three normal control dogs were also monitored. Six additional normal dogs were used for histology control. Paroxysmal atrial fibrillation (PAF) and paroxysmal atrial tachycardia (PAT) were documented in all dogs in the experimental group, with an average of 3.8 (SD 3) episodes/day, including 1.3 (SD 1.6) episodes of PAF and 2.5 (SD 2.2) episodes of PAT. The duration averaged 298 (SD 745) s (range, 7-4,000 s). There was a circadian pattern of arrhythmia onset (P < 0.01). Of 576 episodes of PAF and PAT, 236 (41%) episodes occurred during either sustained or nonsustained ventricular tachycardia (VT). Among these 236 episodes, 53% started before VT, whereas 47% started after the onset of VT. Normal dogs did not have either PAF or PAT. The hearts from the experimental group had a higher density of nerve structures immunopositive (P < 0.01) for three different nerve specific markers in both right and left atria than those of the control dogs. We conclude that the induction of nerve sprouting and sympathetic hyperinnervation in dogs with CAVB and MI creates a high yield model of PAF and PAT.

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Background-Beta3-adrenergic receptor (beta3-AR) stimulation inhibits cardiac contractility.

Objective Transcatheter aortic valve implantation (TAVI) provokes early injury response, represented in part by dynamic changes in the inflammatory markers. The association of self-expanding valves (SEVs) and balloon-expandable valves (BEVs) with the consequent inflammatory response remains uncertain. Materials and methods Patients with severe symptomatic aortic stenosis who underwent transfemoral TAVI: SEVs or BEVs, from January 2010 to December 2019 were enrolled. Whole white blood cells (WBC) and subpopulation dynamics as well the neutrophil to lymphocyte ratio (NLR) were evaluated. Results Three-hundred seventy consecutive patients (mean age 81.75 ± 6.8 years, 199 women’s) were enrolled. In the entire population, significant kinetic changes in the WBC response (p <0.0001) between admission and first 24 hours post procedure, with a significant increase in total WBC (7.46 ± 2.26 to 10.08 ± 3.55) and absolute neutrophil count (4.97 ± 2.06 to 8.19 ± 3.43), NL ratio (3.72 ± 2.8 to 9.76 ± 7.29), and a meaningful decrease in absolute lymphocytes count (1.67 ± 1.1 to 1.1 ± 0.76). When compared between the types of valves, SEVs were associated with a more pronounced inflammatory response than BEVs, with total WBC (10.44 ± 3.86 vs. 9.45 ± 3.19) neutrophils (8.56 ± 3.75 vs. 7.55 ± 3.06) with p 0.016 and 0.012 respectively. Conclusion This is the first description of a differential inflammatory response between the two leading delivery systems. SEV appears to trigger a more robust inflammatory response as compared to BEV. Clinical studies are warranted to assess the long term effect of our findings.