RT-PCR Cycle Threshold for Predicting COVID-19-related Cardiac Complications: A Case-control Study

Introduction: Coronavirus disease-2019 (COVID-19) causes several cardiovascular (CV) complications. The cycle threshold (Ct) value of reverse transcription-polymerase chain reaction is inversely related to the viral load. Thus, it could be used as a predictor of outcomes. We aimed to present the risk factors for developing CV events and to determine whether the Ct value can be used as a predictor of CV events in patients with COVID-19. Materials and Methods: This case-control study included 296 hospitalized patients with a confirmed COVID-19 infection. The patients were divided into two groups based on the occurrence of CV events: cardiac (n=60) and non-cardiac (n=236). The clinical manifestation, comorbidities history, and laboratory and radiographic findings were compared between the two groups. In order to assess the link between CV complications and Ct values while controlling for confounders, binary logistic regression analysis was used. The receiver operating characteristic (ROC) curve analysis was used for estimating the cut-off Ct value for predicting the occurrence of CV events. Results: Approximately 50% of the patients were male. The mean age was 60.85±19.57 years. Binary logistic regression analysis demonstrated that a lower Ct value at the time of admission [odds ratio (OR)=0.836, 95% confidence interval (CI): 0.753-0.928, p=0.001], higher troponin level (OR=1.209, 95% CI: 1.050-1.392, p=0.008), smoking history (OR=7.336, 95% CI: 3.34-16.114, p<0.001), advanced age (OR=1.022, 95% CI: 1.001-1.044, p=0.039), and the male sex (OR=2.742, 95% CI: 1.271-5.919, p=0.010) were independent risk factors of CV events in patients with COVID-19. The median Ct for all participants was 24.6 (21-28). The Ct value demonstrated a sensitivity of 72%, specificity of 72%, negative predictive value of 91%, and positive predictive value of 40% for the prediction of CV complications at a cut-off value of 23, according to an ROC curve analysis. Conclusion: A Ct of <23 at the time of admission for COVID-19 could predict the risk of a CV event. Thus, if patients with risk factors for CV events have a Ct of <23 Ct on admission, they should be evaluated by a competent COVID-19 heart team