Additive prognostic value of interleukin-6 at peak phase of dobutamine stress echocardiography in patients with coronary artery disease. A 6-year follow-up study

Background Interleukin-6 (IL-6) and tissue factor (TF) are elevated after myocardial ischemia during dobutamine stress echo (DSE). We examined the incremental prognostic value of IL-6 or TF measured during DSE over echocardiographic and clinical factors in patients with chronic coronary artery disease (CAD). Methods We studied 106 patients with angiographically documented CAD. IL-6 and TF were measured at rest, peak, and during recovery. A wall motion score index was calculated. Results Fifty-seven (54%) patients had ischemia at DSE. During follow-up (63.7 ± 20 months), 36 patients (33%) had an adverse event (12 cardiac deaths, 24 acute coronary events). Patients with events had a higher peak IL-6 ( P = .02) but similar rest and recovery IL-6 than those without. Patients with peak IL-6 ≥3.14 pg/mL (upper tertile) had a hazard ratio of 2.7 (95% CI 1.44-5.37) ( P < .01 for an adverse event). The addition of peak wall motion score index in a multivariable model including risk factors, ejection fraction, revascularization, and multivessel disease increased the model's c statistic from 0.66 to 0.70 ( P = .04). The addition of peak IL-6 further increased the model's c statistic to 0.75 ( P = .04). Tissue factor was not related with cardiac events. Conclusions Interleuikin-6 levels measured during the peak phase of DSE incrementally contribute to risk stratification in patients with chronic CAD.