Endocrine Abstracts

Background: The growth hormone system (growth hormone, GH and insulin-like-growth-factor I, IGF-I) might be implicated in congestive heart failure (CHF). In experimental models IGF-I increases cardiac contractility and reduces apoptosis of myocytes exposed to ischemic injury. In clinical studies GH-therapy has been used in CHF. One previous population based investigation showed that low levels of IGF-I was associated with an increased incidence of CHF. The result of this investigation was limited by lack of echocardiographic examination at baseline and the established riskmarker B-type natriuretic peptide (BNP) was not taken into consideration.

Objective: To examine the relationship between levels of IGF-I and the risk of development of CHF.

Method: A population based prospective study of 584 individuals (age 50–89 years) without a history of CHF and with normal systolic function at baseline assessed by echocardiography (left ventricular ejection fraction ≥50%). Development of CHF was ascertained after 5-years follow-up.

Cox proportional hazard regression analyses were used for the risk calculations. Results are given by P values and hazard ratio, HR (95% confidence limits) per 1 standard deviation increase in logarithmically transformed IGF-I level.

Results: Nineteen patients developed CHF (3.3%). They had significantly higher baseline levels of age-adjusted IGF-I levels compared to the rest of the population, 89 vs 72 ng/ml, P=0.01 (IGF-I adjusted to a 70-year old individual).

Age-adjusted IGF-I was associated to increased risk of development of CHF, HR=1.64 (1.15–2.35), P=0.007. A multivariable model adjusted for age, levels of N-terminal proBNP (NT-proBNP), the presence of hypertension, atrial fibrillation and diabetes did not attenuate the association, HR=1.67 (1.16–2.40), P=0.006.

Conclusions: In a large middle-aged and elderly normal population high level of IGF-I was an independent riskfactor for development of CHF. The result was unexpected and in contrast to a previous reported protective role of IGF-I.