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Purpose: The COVID-19 pandemic posed unprecedented demands on health care. This study aimed to characterize COVID-19 inpatients and examine trends and risk factors associated with hospitalization duration, intensive care unit (ICU) admission, and in-hospital mortality. Methods: This retrospective study analyzed patients with SARS-CoV-2 infection hospitalized at an integrated health system between February 2, 2020, and December 12, 2020. Patient characteristics and clinical outcomes were obtained from medical records. Backward stepwise logistic regression analyses were used to identify independent risk factors of ICU admission and in-hospital mortality. Cox proportional hazards models were used to evaluate relationships between ICU admission and in-hospital mortality. Results: Overall, 9647 patients were analyzed. Mean age was 64.6 ± 18 years. A linear decrease was observed for hospitalization duration (0.13 days/week, R2=0.71; P<0.0001), ICU admissions (0.35%/week, R2=0.44; P<0.001), and hospital mortality (0.16%/week, R2=0.31; P<0.01). Bacterial co-infections, male sex, history of chronic lung and heart disease, diabetes, and Hispanic ethnicity were identified as independent predictors of ICU admission (P<0.001). ICU admission and age of ≥65 years were the strongest independent risk factors associated with in-hospital mortality (P<0.001). The in-hospital mortality rate was 8.3% (27.4% in ICU patients, 2.6% in non-ICU patients; P<0.001). Conclusions: Results indicate that, over the pandemic's first 10 months, COVID-19 carried a heavy burden of morbidity and mortality in older patients (>65 years), males, Hispanics, and those with bacterial co-infections and chronic comorbidities. Although disease severity has steadily declined following administration of COVID-19 vaccines along with improved understanding of effective COVID-19 interventions, these study findings reflect a "natural history" for this novel infectious disease in the U.S. Midwest.
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Multielectrode array (MEA) technology has been extensively used for field potential recordings from excitable cells. However, its application for action potential (AP) measurements has not been harnessed. Here, we report a novel platform for high-resolution intracellular AP recordings from induced pluripotent stem cell-cardiomyocyte constructs derived from human cardiac fibroblasts. To gain intracellular access, micro-gold MEAs were used to electroporate multiple constructs simultaneously. High-throughput AP measurements were obtained from 41 multicellular constructs. Repeated electroporations of the same cells did not affect the signal stability. Our model has the capability to distinguish subtle differences in AP morphology to characterize the network profile. Furthermore, we confirm the reliability of the system by recapitulating known drug-induced physiological and arrhythmogenic responses. Overall, the model provides a unique cardio-electronic interface for non-invasive measurements of AP dynamics for drug screening and disease modeling. This technology opens the door for identifying novel cardio-factors to enhance electrophysiological maturation.