Relationship between interleukin-6 and cardiac involvement in systemic sclerosis.

Objectives: To explore the relationship between IL-6 levels and echocardiographic abnormalities, and N-terminal probrain natriuretic peptide (NT-proBNP) levels in SSc patients and to correlate tested parameters with European Scleroderma Activity (EUSTAR) score.

Methods: This case-control study included 31 SSc patients with preserved left ventricular ejection fraction (LVEF) and 32 matched healthy controls. Serum IL-6 and NT-proBNP levels were measured and subjects were evaluated by conventional and pulsed-wave tissue Doppler echocardiography.

Results: The level of IL-6 was significantly increased in patients with SSc (3.2 vs 2.2 pg/ml, P < 0.001). SSc patients had significantly lower values of LV systolic (7.7 vs 9.25 cm/s, P < 0.001) and early diastolic (8.7 vs 10.3 cm/s, P = 0.014) myocardial velocities and higher E/e' (9.04 vs 7.37, P = 0.001) ratio, although there was no between-group difference according to LVEF (68% vs 65%, P = 0.248). On evaluating the right ventricle there was no significant between-group difference in systolic tricuspid annular velocity (13 vs 13.9 cm/s, P = 0.105), but the peak early diastolic velocity was significantly lower (11.7 vs 13.6, P = 0.044) and E/e' was significantly higher (4.3 vs 3.38, P = 0.008) in SSc patients. IL-6 level showed correlation with LV mean e' (r = -0.57, P = 0.001), E/e' (r = 0.55, P = 0.001) and NT-proBNP (r = 0.52, P = 0.003). EUSTAR score correlated with LV E/e' (r = 0.48, P = 0.006), mean e' (r = -0.67, P < 0.001), mean s' (r = -0.51, P = 0.004), NT-proBNP (r = 0.60, P < 0.001) and IL-6 (r = 0.79, P < 0.001).

Conclusion: IL-6 level is increased in patients with SSc and significantly correlates with LV diastolic dysfunction, NT-proBNP and EUSTAR score. These results support the role of IL-6 in the development of cardiac disease in SSc patients.