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Effects of cardiac resynchronization therapy on insulin-like growth factor-1 in patients with advanced heart failure

Background Although a more favorable neurohormonal balance may contribute to improving symptoms following cardiac resynchronization therapy (CRT), no information is available regarding the effects of CRT on insulin-like growth factor-1 (IGF-1). This study assessed the effects of CRT on IGF-1 levels and their correlation with changes in quality of life and left ventricular (LV) function. Methods and Results Patients with cardiomyopathy in New York Heart Association class III or IV (n = 18; age 71 ± 10 years), left ventricular ejection fraction (LVEF) ≤ 40% and QRS ≥ 130 ms or ventricular dyssynchrony were enrolled in the study and followed up for 6 months. After 3 months, there was an improvement in LVEF (from 29 ± 7 to 33 ± 10%, P = 0.0136) and quality of life (from 33 ± 14 to 13 ± 12, P = 0.0000) and an increase in IGF-1 levels (from 137 ± 79 to 175 ± 111 ng/ml, P = 0.01353). The change in quality of life correlated with changes in IGF-1 levels (P = 0.02) but not with LVEF changes. Conclusions In patients with advanced heart failure, CRT leads to a significant increase in plasma IGF-1 levels within 3 months. This increase is correlated with the improvement in quality of life, whereas the increase in LVEF is not. This finding suggests that IGF-1 may play a role as a mediator in the early phase of symptomatic improvement after CRT.