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) < or = 40% and QRS > or = 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.