Effects of treatment with somatostatin analogues on QT interval duration in acromegalic patients.
OBJECTIVE
Cardiovascular disease is a major contributor to the increased mortality of acromegalic patients. Prolongation of the QT interval is considered an established risk factor for potentially fatal cardiac arrhythmias, an event frequently observed in acromegaly. Changes in ventricular repolarization have been observed with the use of octreotide, one of the somatostatin analogues (SSA) currently used for the medical treatment of this disease. Furthermore, octreotide is listed among the drugs able to prolong the QT interval. Thus, we elected to study the effects of long-term SSA administration on QT duration and left ventricular mass (LVM) in a group of acromegalic patients.


METHODS
In a retrospective study, 30 acromegalic patients (19 women and 11 men, aged 25-77 years) were studied under basal conditions; 24 of them (15 women and nine men, aged 25-77 years) were studied again after 3-63 months of treatment (median 18 months) with SSA. Twenty-four healthy volunteers served as controls.


METHODS
Patients and controls underwent electrocardiographic (ECG) analysis, and QT interval duration corrected for heart rate (QTc) was established according to the Bazett formula. In 17 of the SSA-treated patients, M- and B-mode echocardiography for the assessment of LVM index (LVMi) was performed.


RESULTS
Baseline QTc was significantly longer in patients than in controls. SSA administration was followed by a significant decrease in QTc, which reached a mean value similar to that measured in the controls. In particular, treatment with SSA normalized QTc in three out of the six patients with abnormally elevated values at baseline. After treatment, a significant reduction in heart rate was recorded, while LVMi displayed a slight but not significant decrease.


CONCLUSIONS
Acromegalic patients frequently display an abnormally prolonged QT interval, a known risk factor for potentially fatal arrhythmias. Treatment of these patients with SSA is able to improve and even normalize this alteration, probably contributing to the beneficial effects of these drugs on cardiac rhythm in this endocrine disorder. The inclusion of octreotide in the list of drugs that may increase QTc should be reconsidered as regards its indication in acromegaly.
Fatti
Letizia Maria
LM
University of Milan, Division of Endocrinology, Ospedale San Luca IRCCS, Istituto Auxologico Italiano, Italy.
Scacchi
Massimo
M
Lavezzi
Elisabetta
E
Pecori Giraldi
Francesca
F
De Martin
Martina
M
Toja
Paola
P
Michailidis
Georgios
G
Stramba-Badiale
Marco
M
Cavagnini
Francesco
F
D000172:Acromegaly / Q000097:blood / Q000188:drug therapy* / Q000503:physiopathology; D000328:Adult; D000368:Aged; D018931:Antineoplastic Agents, Hormonal / Q000627:therapeutic use*; D016022:Case-Control Studies; D004452:Echocardiography / Q000187:drug effects; D004562:Electrocardiography / Q000187:drug effects; D005260:Female; D013006:Growth Hormone / Q000097:blood; D006329:Heart Conduction System / Q000187:drug effects*; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000032:analysis; D016014:Linear Models; D008133:Long QT Syndrome / Q000188:drug therapy; D008297:Male; D008875:Middle Aged; D015282:Octreotide / Q000627:therapeutic use*; D012189:Retrospective Studies
D018931:Antineoplastic Agents, Hormonal; D007334:Insulin-Like Growth Factor I; D013006:Growth Hormone; D015282:Octreotide