Arrhythmic Risk Assessment of Hypokalaemia Using Human Pluripotent Stem Cell-Derived Cardiac Anisotropic Sheets

Nonlinear analysis of beat-to-beat variability of action potential time series data identifies dynamic re-entrant substrates in a hypokalaemic mouse model of acquired long QT syndrome

Background

Previous studies have quantified repolarization variability using time-domain, frequency-domain and nonlinear analysis in mouse hearts. Here, we investigated the relationship between these parameters and ventricular arrhythmogenicity in a hypokalaemia model of acquired long QT syndrome.

Methods

Left ventricular monophasic action potentials (MAPs) were recorded during right ventricular regular 8 Hz pacing during normokalaemia (5.2 mM [K+]), hypokalaemia modeling LQTS (3 mM [K+]) or hypokalaemia with 0.1 mM heptanol in Langendorff-perfused mouse hearts.

Results

During normokalaemia, mean APD was 33.5 ± 3.7 ms. Standard deviation (SD) of APDs was 0.63 ± 0.33 ms, coefficient of variation was 1.9 ± 1.0% and the root mean square (RMS) of successive differences in APDs was 0.3 ± 0.1 ms. Low- and high-frequency peaks were 0.6 ± 0.5 and 2.3 ± 0.7 Hz, respectively, with percentage powers of 38 ± 22 and 61 ± 23%. Poincaré plots of APDn+1 against APDn revealed ellipsoid morphologies with SD along the line-of-identity (SD2) to SD perpendicular to the line-of-identity (SD1) ratio of 4.6 ± 1.1. Approximate and sample entropy were 0.49 ± 0.12 and 0.64 ± 0.29, respectively. Detrended fluctuation analysis revealed short- and long-term fluctuation slopes of 1.62 ± 0.27 and 0.60 ± 0.18, respectively. Hypokalaemia provoked ventricular tachycardia in six of seven hearts, prolonged APDs (51.2 ± 7.9 ms), decreased SD2/SD1 ratio (3.1 ± 1.0), increased approximate and sample entropy (0.68 ± 0.08 and 1.02 ± 0.33) and decreased short-term fluctuation slope (1.23 ± 0.20) (ANOVA, P < 0.05). Heptanol prevented VT in all hearts studied without further altering the above repolarization parameters observed during hypokalaemia.

Conclusion

Reduced SD2/SD1, increased entropy and decreased short-term fluctuation slope may reflect arrhythmic risk in hypokalaemia. Heptanol exerts anti-arrhythmic effects without affecting repolarization variability.

Assessment of hypokalemia and clinical prognosis in Patients with COVID-19 in Yangzhou, China

Background

Hypokalemia is a frequent electrolyte imbalance in patients with COVID-19. The aim of this study was to estimate the association between hypokalemia and clinical prognosis in patients with moderate COVID-19.

Methods

A single-center, retrospective, observational study was conducted on 81 non-ICU admitted patients with moderate COVID-19 according to the criteria issued by the Chinese Health Bureau in the Third People’s Hospital of Yangzhou (Northern Jiangsu People’s Hospital New District Branch) from 4th to 25th August 2021. The demographic, clinical, and laboratory data were reviewed and collected, then the correlation between hypokalemia and prognosis was determined.

Results

The level of serum potassium of patients ranged from 2.80 mmol/L to 4.70 mmol/L. Hypokalemia was detected in 39 out of the 81 included patients (48.15%) during hospitalization. Patients with hypokalemia had prolonged days of negative nucleic acid conversion and hospital stay. Correlation analysis showed that the level of serum potassium was negatively correlated with days of negative nucleic acid conversion and length of hospital stay. Bivariate logistic regression analysis proved that hypokalemia was a risk factor for prolonged hospital stay in patients with moderate COVID-19.

Conclusion

Hypokalemia was prevalent in patients with moderate COVID-19 in Yangzhou, China. Hypokalemia was associated with the prolonged hospital stay in patients with moderate COVID-19.