Introductions. Inflammation plays a crucial role in the occurrence and progression of atherosclerosis. Recent studies have explored the clinical effects of inflammatory reactions in the development of coronary heart disease. They found that different subtypes of leukocytes—specifically neutrophils, lymphocytes, and monocytes—provide more predictive value for assessing the risk of cardiovascular disease than just the total leukocyte count. Additionally, several studies have reported hematological abnormalities in COVID-19 patients. These abnormalities include an increase in white blood cell count, as well as a decrease in red blood cell count and hemoglobin levels. Such alterations are associated with a higher risk of severe disease and poorer outcomes. Smoking is also a recognized risk factor, as noted in the Framingham Heart Study. Smokers face an increased risk of myocardial infarction or sudden cardiac events.
Aim. To evaluate the levels of leukocyte inflammatory markers in patients with unstable angina and post-COVID-19 syndrome, based on smoking status.
Materials and Methods. The study involved 147 patients with unstable angina aged between 35 and 76 years, with a mean age of 60.32 ± 0.66 years. Among the participants, 17.69% (n=26) were women, while 82.31% (n=121) were men. The presence of post-COVID syndrome was assessed using the POSTCOVID-19 Functional Status Scale, which allowed for the division of patients into two groups: group (I) comprised 87 patients (59.18%) with post-COVID syndrome, and group (II) included 60 individuals (40.81%) without post-COVID syndrome. Each group was further categorized into subgroups based on smoking status: subgroup IA and IIA consisted of smokers, while subgroup IB and IIB comprised non-smokers. The study measured several leukocyte inflammatory markers, including the Neutrophil-to-Lymphocyte Ratio (NLR), Monocyte-to-Lymphocyte Ratio (MLR), Systemic Immune Inflammation Index (SII), Systemic Inflammation Response Index (SIRI), and Aggregate Index of Systemic Inflammation (AISI). Comparisons were made between the subgroups: IA and IIB, IA and IIA, as well as IB and IIB, taking into account the presence or absence of post-COVID syndrome and smoking status.
Results and discussion. The data obtained revealed that mean Neutrophil-Lymphocyte Ratio (NLR) levels were significantly higher in the smoking subgroup experiencing post-COVID syndrome (designated as IA) compared to the non-smoking subgroup without post-COVID syndrome (designated as IIB). Specifically, NLR levels in subgroup IA were 50% greater, measuring 3.47±0.85×10⁹/L, compared to 1.73±0.12×10⁹/L in subgroup IIB (p<0.03). Additionally, the average Monocyte-Lymphocyte Ratio (MLR) was also significantly elevated in subgroup IA by 37.9%, with values of 0.29±0.04×10⁹/L for IA versus 0.18±0.02×10⁹/L for IIB (p<0.03). The aggregate indices of leukocyte inflammation, including Systemic Inflammatory Index (SII), Systemic Inflammatory Response Index (SIRI), and Aggregate Immune Score Index (AISI), were significantly higher in subgroup IA, ranging from 52% to 62% compared to subgroup IIB. Specifically, SII was 52.7% higher (803.81±163.64×10⁹/L for IA vs. 380.42±34.78×10⁹/L for IIB, p<0.009), SIRI was 60.8% higher (2.02±0.60×10⁹/L for IA vs. 0.80±0.09×10⁹/L for IIB, p<0.02), and AISI was 62.7% higher (466.64±115.80×10⁹/L for IA vs. 174.06±24.32×10⁹/L for IIB, p<0.01). When comparing smokers with post-COVID syndrome (IA) to smokers without post-COVID syndrome (IIA), MLR was 37.93% higher in the IA subgroup (0.29±0.04×10⁹/L for IA vs. 0.18±0.02×10⁹/L for IIA, p<0.02). SIRI was 55.9% higher (803.81±163.64×10⁹/L for IA vs. 380.42±34.78×10⁹/L for IIA, p<0.05), and AISI was 53.99% higher (466.64±115.80×10⁹/L for IA vs. 174.06±24.32×10⁹/L for IIA, p<0.03). Among non-smokers, individuals with post-COVID syndrome (IB) exhibited significantly higher levels of inflammatory leukocyte markers compared to non-smokers without post-COVID syndrome (IIB), showing increases of 33% to 40%. Specifically, NLR was 34.2% higher (2.63±0.22×10⁹/L for IB vs. 1.73±0.12×10⁹/L for IIB, p<0.005), SII was 39.16% higher (625.26±57.12×10⁹/L for IB vs. 380.42±34.78×10⁹/L for IIB, p<0.001), SIRI was 33.88% higher (1.21±0.12×10⁹/L for IB vs. 0.80±0.09×10⁹/L for IIB, p<0.01), and AISI was 39.57% higher (288.05±32.20×10⁹/L for IB vs. 174.06±24.32×10⁹/L for IIB, p<0.006).
Conclusions. Patients with unstable angina who present with both post-COVID syndrome and a history of smoking (IA) demonstrate the highest average levels of leukocyte inflammatory markers. In comparison, smokers without post-COVID syndrome (IIA) and non-smokers in general (IB and IIB) exhibit lower levels. It is noteworthy that non-smokers with post-COVID syndrome (IB) still display elevated levels of leukocyte inflammatory markers relative to non-smokers without post-COVID syndrome (IIB). These results indicate that both post-COVID syndrome and smoking may independently exert pro-inflammatory effects, leading to a significantly enhanced inflammatory response, as reflected by increased average levels of leukocyte inflammatory markers in the affected subgroups. The interplay between these factors serves to amplify their individual effects, culminating in a markedly pronounced inflammatory response.
Keywords: ischemic heart disease, unstable angina, COVID-19, post-COVID syndrome, smoking, inflammation markers.