Endocrine Abstracts

Background: Testosterone treatment has been shown to increase exercise capacity in men with chronic heart failure but the mechanism of benefit is unclear. The purpose of this study was to examine the acute haemodyamic effects of testosterone in men with heart failure.

Methods: Twelve men with stable heart failure (age 62.8 (8.8)years; ejection fraction 30.9 (6.3)% (NR>60%)) were enrolled in a double-blind, placebo-controlled cross-over study. Cardiac output and left ventricular pre-load and after-load were assessed invasively using a balloon-flotation catheter. Subjects were given testosterone 60mg or placebo. Measurements were recorded at t=0, 30, 60, 120, 180, 240, 300 and 360 minutes, and repeated the following day with the second test drug. The order of drug administration was randomised. Changes in parameters were compared between the two treatments by ANCOVA and are presented as % change from baseline.

Results: Serum total testosterone levels rose rapidly in the active treatment arm, from 13.5 (4.5)nmol/L to 96.2 (47.8)nmol/L. Throughout each treatment period, cardiac index fell, but this was markedly attenuated by testosterone treatment (p<0.0001), with maximum treatment effect at 180 minutes (10.3 (4.6)% from baseline, p=0.035; 95% CI 0.8 to 19.8). Similarly, a rise in systemic vascular resistance during placebo treatment was significantly reduced by testosterone (p<0.0001), with maximum treatment effect at 180 minutes (-17.4 (9.6)% from baseline, p=0.085, 95% CI -37.3 to +2.6). The treatment effect was significantly greater throughout the study in men with bio-available testosterone levels below the median value at baseline (p<0.0001 for both cardiac index and systemic vascular resistance, ANCOVA). There was no effect of treatment on heart rate, arterial blood pressure or measures of left ventricular pre-load.

Conclusion: Acute administration of testosterone augments cardiac output compared with placebo, apparently via reduction of left ventricular afterload.