14th International Congress
THE "NEW FRONTIERS"
OF ARRHYTHMIAS 2000

Jan. 29 - Feb. 5, 2000
Marilleva, Trento, Italy

RT-143

Growth hormone (GH) acute effects on electrophysiological cardiac parameters in humans

Cristoforo D’Ascia, Antonio Cittadini, Giuseppe Riccio, Luigi De Vito, Salvatore Longobardi, Salvatore Luca D’Ascia, Carlo Pappone*, Luigi Sacca.
Department of Internal Medicine, “Federico II” University Medical School Naples, *San Raffaele Hospital, Milan, Italy

Background

The first description of cardiac arrhythmias in acromegalic patients dates back to 100 hundred years ago¹. In acromegalic patients, life expectancy was reduced by approximately 80% due to cardiovascular diseases². This observation is not entirely congruent with a recent retroscpective study which found a mortality rate of only 24% in acromegalic patients due to cardiovascular complications³.

Furthermore, in a subsequent prospective study performed in 57 acromegalics, the acromegalic cardiopathy was present only in patients with concomitant hypertension or congestive heart failure⁴.

Echocardiographic studies, radionuclide imaging, and cardiac catheterization have documented abnormal left ventricular measurements in a considerable proportion of acromegalic patients^5-7.

However, little is know about the incidence and the severity of cardiac arrhythmias in acromegaly and their relation to endocrine and clinical parameters. In a controlled study, cardiac involvement and arrhythmia profile were correlated with endocrine parameters (Growth hormone, GH, and Insuline like growth factor I, IGF-I), clinical score, and duration of disease⁸. Specifically, prevalence and severity of ventricular arrhythmias were significantly higher in acromegalics compared to controls and no correlation was found between the severity of ventricular arrhythmias and hormonal levels. The severity of ventricular arrhythmias was correlated with both left ventricular mass and with the clinical activity score. As expected, also left ventricular hypertrophy was found at echocardiography⁸.

To date, no study has addressed whether GH administration modifies electrophysiological cardiac parameters and/or the induction of arrhythmias in an acute setting. Thus, the purpose of this controlled study was 1) to evaluate the endocavitary electrophysiological profile in patients without structural cardiac abnormalities, whose chief complain was palpitations, during acute administration of growth hormone and, 2) to investigate the correlation between hormone levels (GH and IGF-I) and cardiac arrhythmias.