Growth Hormone Therapy

, Is it Always Good for the Heart?

Vicente Climenta,*, Francisco Marína, Antonio Picób and Francisco Sogorba

a Department of Cardiology, General Hospital of Alicante, Alicante, Spain
b Deparment of Endocrinology, General Hospital of Alicante, Alicante, Spain

* Corresponding author: Vicente E. Climent, Department of Cardiology, General Hospital of Alicante, Pintor Baeza s/n. 03002 Alicante, Spain
E-mail address: vcliment{at}coma.es

Received 27 July 2003; revised 4 August 2003; accepted 14 August 2003

We read with interest the article of Cittadini et al.1about the effects of growth hormone (GH) therapy on cardiac structure and function in Becker and Duchenne muscular dystrophies. Large evidences demonstrate that the growth hormone/insuline-like growth factor-1 (GH/IGF-1) axis could have great relevance for the regulation of cardiac growth, structure and function.2However, recent studies have raised the point that the use of GH therapy in GH deficient (GHD) adults in order to improve cardiac function is debatable.3

We have studied 51 adult patients (35 men; mean age 37±15 years; 23 childhood-onset growth hormone deficiency) with chronic GH deficient syndrome and 31 normal subjects (17 men; mean age 38±14 years). We did not find any significant differences in left ventricular mass, systolic or diastolic function indices compared with controls. By contrast, blood pressure (BP) values were lower in patients than in controls (Systolic BP: 113 (108–117) vs 135 (131–140)mmHg; Diastolic BP: 68 (59–71) vs 76 (69–83); P<0.01. Results are expressed as median and interquartile range). The duration of the exercise on the treadmill test was shorter in the GHD group (9'40'' (6'20''-10'51'') vs 12'42'' (12'00''-14'05'') minutes; P<0.01).4

Patients who initiated GH therapy were re-evaluated at 6, 12 and 24 months under GH therapy (11, 8 and 12 patients, respectively). No changes were observed in echocardiographic or exercise parameters after GH treatment. In view of these results we may conclude that short and long-term GH substitution in GHD syndrome is not associated with significant changes in cardiac structure or function.

Controversial data exists about the use of GH in primary heart diseases such as dilated cardiomyopathy. Previous non-randomized clinical studies using GH demonstrated an improvement in the clinical status of patients with idiopathic cardiomyopathy, whilst recent randomized placebo-controlled studies did not confirm these results.5In the article of Cittadini et al., the authors found after only 3-month therapy in Becker and Duchene dystrophies a significant increase in left ventricular mass. An important limitation of this study, as pointed by authors in the discussion, is the small sample size treated with GH (3 patients in Duchenne group and 6 patients in Becker group) and the high prevalence of GH/IGF-1 axis abnormalities in the group treated with GH. On the other hand, therapy with recombinant human GH, commonly administered as a single weekly dose, resulting in a constant, and small elevation of circulating GH concentrations which confers a pattern completely different than pulsatile fashion. This constant elevation of GH could be similar to the situation observed in acromegalic patients, which have typically lost the pulsatile secretion. It may result in a higher rate of complications. We should not forget that the most common cause of mortality in acromegaly is cardiovascular diseases.2Moreover, the GH-induced left ventricular hypertrophy is not usually accompanied by an improvement in left ventricular ejection fraction as it is shown in the article of Cittadini. From thisevidence, a careful attitude concerning the clinical utility of GH as coadjutant treatment in cardiomyopathies should be maintained until further data areavailable.

References

  1. Cittadini A, Comi L, Longobardi S et al. A preliminary randomized study of growth hormone administration in Becker and Duchenne muscular dystrophies. Eur Heart J. 2003;24:664–672.[Abstract/Free Full Text]
  2. Saccá L, Cittadini A, Fazio S. Growth Hormone and the Heart. Endocr Rev. 1994;15:555–573.[Abstract]
  3. Vance ML, Mauras N. Growth hormone therapy in adults and children. N Eng J Med. 1999;341:1206–1216.[Free Full Text]
  4. Climent V, Marín F, Valencia P et al. Influence of growth hormone in rhythm of blood pressure. Results in adults patients with deficiency in this hormone. Rev Esp Cardiol. 2001;54:469–475.[Medline]
  5. Acevedo M, Carbalán R, Chamorro G et al. Administration of growth hormone to patients with advanced cardiac heart failure: effects upon left ventricular function, exercise capacity, and neurohormonal status. Int J Cardiol. 2003;87:185–191.[CrossRef][Medline]