Poor prognosis of patients with severe COVID-19 admitted to an infectious disease intensive care unit during the pandemic caused by the Delta variant in Japan.

During the surge of coronavirus disease (COVID-19) caused by the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) delta variant, our institution operated an intensive care unit (ICU) for patients with severe COVID-19. The study aim was to determine the survival rate and treatment outcomes of patients with severe COVID-19 treated in the ICU during the surge. A total of 23 consecutive patients with severe COVID-19 were admitted to the ICU between August 5 and October 6, 2021. Patients received multidrug therapy consisting of remdesivir, tocilizumab, heparin, and methylprednisolone. The patients were divided into two groups based on the ordinal scale (OS): a non-invasive oxygen therapy (OS-6) group, and an invasive oxygen therapy (OS-7) group. There were 13 (57%) and 10 (43%) patients in the OS-7 and OS-6 groups, respectively. All patients were unvaccinated. Sixteen patients (70%) were male. The median age was 53 years; the median body mass index (BMI) was 30.3 kg/m2; and the median P/F ratio on admission was 96. The 30-day survival rate was 69% and was significantly poorer in the OS-7 group (54%) than in the OS-6 group (89%; p = 0.05). The prevalence of obesity (p = 0.05) and the Sequential Organ Failure Assessment (SOFA) score on admission (p < 0.01) were significantly higher in the OS-7 group. Seven patients in the OS-7 group (54%) developed bacteremia. A low P/F ratio on admission was a significant unfavorable prognostic factor (hazard ratio: 10.9; p = 0.03). The survival rate was poor, especially in patients requiring invasive oxygen therapy. More measures are needed to improve the treatment outcomes of patients with severe COVID 19.

Increased predominance of the matured ventricular subtype in embryonic stem cell-derived cardiomyocytes in vivo.

Accumulating evidence suggests that human pluripotent stem cell-derived cardiomyocytes can affect "heart regeneration", replacing injured cardiac scar tissue with concomitant electrical integration. However, electrically coupled graft cardiomyocytes were found to innately induce transient post-transplant ventricular tachycardia in recent large animal model transplantation studies. We hypothesised that these phenomena were derived from alterations in the grafted cardiomyocyte characteristics. In vitro experiments showed that human embryonic stem cell-derived cardiomyocytes (hESC-CMs) contain nodal-like cardiomyocytes that spontaneously contract faster than working-type cardiomyocytes. When transplanted into athymic rat hearts, proliferative capacity was lower for nodal-like than working-type cardiomyocytes with grafted cardiomyocytes eventually comprising only relatively matured ventricular cardiomyocytes. RNA-sequencing of engrafted hESC-CMs confirmed the increased expression of matured ventricular cardiomyocyte-related genes, and simultaneous decreased expression of nodal cardiomyocyte-related genes. Temporal engraftment of electrical excitable nodal-like cardiomyocytes may thus explain the transient incidence of post-transplant ventricular tachycardia, although further large animal model studies will be required to control post-transplant arrhythmia.