Increased troponin I blood level and in-hospital outcome across successive COVID-19 waves

Abstract Introduction Troponin I blood level (TnI) is often elevated in patients hospitalized due to COVID-19, and high TnI is associated with adverse outcomes, in this scenario. However, the case rate of high TnI in hospitalized patients and respective case fatality rates (CFR) across different COVID-19 waves still demand investigation, as emerging SARS-CoV-2 variants may affect the cardiac tissue diversely. This study investigated the case rate of high TnI and respective in-hospital outcome in patients hospitalized due to COVID-19 during successive pandemic waves. Methods In a retrospective observational cohort study, patients hospitalized due to COVID-19 from March 1st 2020 to July 31st 2022 in a reference hospital were analyzed. Inclusion criteria were: positive SARS-CoV-2 RT-PCR, hospitalization in a COVID-19 cohort ward or ICU, and at least one TnI assessed during hospitalization. Patients presenting acute coronary syndromes were excluded. TnI was assessed using electrochemiluminescence technique, and the highest value during hospital stay considered for analysis. TnI was positive (+) if above normality reference level and negative (-), otherwise. Outcome was in-hospital survival. Age on admission, total length-of-stay (TLOS), TnI(+) case rate, and CFR (the rate of non-survivors to COVID-19 admissions) were analyzed. COVID-19 waves were analyzed on 7-day moving average positive cases series (1), and respective onset and offset assessed by change point detection algorithm and visual inspection. In each wave period, dominants circulating variants from surveillance data (2,3) were matched. Discrete variables were described as percentage and analyzed by Chi-squared test. Continuous variables were described as mean ± SD, and compared by Student t or 1-factor ANOVA test as appropriate. Bicaudal 95% confidence interval (CI) was calculated as needed. Alpha error level was set at 0.05. Results From March 1st 2020 to July 31st 2022, six COVID-16 waves were identified, and 628 patients met the inclusion criteria. Overall, TnI(+) case rate was 72.0% (95% CI [68.4% - 75.4%]), and CFR was higher among TnI(+) (63.7%) than TnI(-) (32.4%; p < 0.001). As of March 1st 2020, there was a significant trend toward increasing TnI(+) case rate (p trend < 0.001) and decreasing CFR in both TnI(+) (p trend < 0.001) and TnI(-) (p trend < 0.01) across successive COVID-19 waves. Patients with TnI(+) were older (66.1 ± 14.7 years old) and had a longer TLOS (27.8 ± 24.5 days) than with TnI(-) (respectively, 59.0 ± 15.7 years old and 20.6 ± 17.0 days; p < 0.001 for both). TnI(+) case rate, TnI(+)-related and TnI(-)-related CFR, age, and TLOS across COVID-19 waves are in Table 1. Conclusion From March 1st 2020 to July 31st 2022, in patients hospitalized due to COVID-19, TnI(+) was associated with increased case fatality rate as compared to TnI(-), across six successive COVID-19 waves. Patients presenting TnI(+) were older and had longer total length-of-stay as compared to TnI(-).Table 1