Supraphysiological Testosterone Levels Shorten the QT Interval but doNot Alter Total Anatomic Myocardial Infarct Size in Rabbits with AcuteMyocardial Infarction

Introduction: A growing number of men are using exogenous testosterone (T) to treat hypogonadism and to enhance athletic performance. However, some studies suggested that T increased adverse cardiovascular events. Although T has been shown to increase apoptosis, its effect on total acute myocardial infarction (MI) size is largely unknown. We hypothesized that T might increase MI size. Materials and Methods: Male rabbits received an intramuscular injection of either T (50 mg/kg) or saline one week before receiving 30 minutes of coronary artery occlusion/3 hours of coronary artery reperfusion. Results: The T levels in the treated group were higher than those of the control group: 15 ± 1 ng/mL T (n=18) versus 1 ± 1 ng/mL control (n= 20, P<0.01). Anatomic MI size (tetrazolium staining) expressed as a percentage of the ischemic risk zone (blue dye technique) was similar in both groups: 37 ± 3% in controls and 37 ± 5% in the T group (P= 0.96). T significantly shortened the QTc interval by 9% (P=0.03). Conclusions: Supra physiological levels of T did not increase infarct size. T shortened the QTc interval, which may create an anti-arrhythmic substrate.