Abstract
BACKGROUND
Interleukin-6 (IL-6) is an inflammation-related cytokine associated with an elevated risk of cardiovascular events. In a previous study, we demonstrated that increased IL-6 was predictive of sub-clinical atherosclerotic coronary disease in intermediate-risk patients undergoing coronary angiography. In the present study, we investigated whether increased serum IL-6 is predictive of cardiovascular events in high-risk patients.
METHODS
In this observational study, consecutive patients referred for elective coronary angiography due to stable chest pain/myocardial ischemia had IL-6 measured immediately before the procedure. Long-term follow-up was performed by phone call or e-mail, and their clinical registries were revised. The primary outcome was a composite of new myocardial infarction, new ischemic stroke, hospitalization due to heart failure, new coronary revascularization, cardiovascular death, and death due to all causes.
RESULTS
From the 141 selected patients, 100 completed the IL-6 analysis and were followed for a mean of 5.5 years. The median age was 61.1 years, 44% were men, and 61% had type-2 diabetes. The median overall time-to-event for the primary outcome was 297 weeks (95% confidence interval [CI] = 266.95–327.16). A receiver operator characteristic curve defined the best cut-off value of baseline serum IL-6 (0.44 pg/mL) with sensitivity (84.37%) and specificity (38.24%) to define two groups. High IL-6 level was moderately predictive of cardiovascular events. ( p for interaction = 0.015) (hazard ratio = 2.81; 95% CI = 1.38–5.72, p=0.01). The subgroup analysis did not find interactions between patients with or without diabetes, obesity, or hypertension.
CONCLUSION
This preliminary study indicates that, in high-risk symptomatic patients undergoing elective coronary angiography, increased pre-procedure serum levels of IL-6 predicted long-term cardiovascular outcomes. These results were similar irrespective of diabetes, hypertension, or obesity status. IL-6 must be studied in larger long-term follow-up studies as a potential tool to re-classify patients with increased cardiovascular risk.
Increased serum IL-6 is predictive of long-term cardiovascular events in high-risk patients submitted to coronary angiography: an observational study.
