Heart failure is a devastating condition that occurs when the heart becomes too weak to pump enough blood to meet the body’s needs. In time the condition leads to a build-up of fluid in the lungs, resulting in breathlessness and swelling of different parts of the body. There are currently no effective treatments for heart failure.
Now a new study, funded by the British Heart Foundation, reports that a common drug used to treat erectile dysfunction can slow and even reverse the progression of heart failure in sheep.
The study is a considered a major breakthrough in the treatment of heart failure, a disease with a five-year survival rate that is lower than most common cancers.
The study of Tadalafil – which is in the same class as Viagra – proves that the drug is biologically effective as a treatment for heart failure in sheep. Lead author Professor Andrew Trafford argues the effect is likely to also be shown in humans. The study is published in the journal Scientific Reports.
“This discovery is an important advance in a devastating condition which causes misery for thousands of people across the UK and beyond,” said Professor Trafford.
“We do have limited evidence from human trials and epidemiological studies that show Tadalafil can be effective in treating heart failure.
The study provides further confirmation, adds mechanistic details and demonstrates that Tadalafil could now be a possible therapy for heart failure.
“It’s entirely possible that some patients taking it for erectile dysfunction have also unwittingly enjoyed a protective effect on their heart.”
Sheep were used by the team as the physiology their hearts is similar to human hearts. The team administered the drug to animals with heart failure, and within a short period of time the progressive worsening of the heart failure stopped. Significantly, the drug also reversed the effects of heart failure.
The biological cause of breathlessness in heart failure – the inability of the heart to respond to adrenaline – was almost completely reversed.
The dose given to the sheep was similar to the dose given to humans being treated for erectile dysfunction.
Tadalafil works by blocking an enzyme called Phosphodiesterase 5, or PDE5S for short, which regulates how body tissues respond to hormones like adrenaline.
The research team found that in heart failure, the drug altered the signaling cascade – a series of chemical reactions in the body – to restore the hearts ability to respond to adrenaline. And that increases the ability of the heart to force blood around the body when working harder.
According to Professor Metin Avkiran, Associate Medical Director at the British Heart Foundation: “Viagra-type drugs were initially developed as potential treatments for heart disease before they were found to have unexpected benefits in the treatment of erectile dysfunction. We seem to have gone full-circle, with findings from recent studies suggesting that they may be effective in the treatment of some forms of heart disease – in this case, heart failure.
“We need safe and effective new treatments for heart failure, which is a cruel and debilitating condition that affects almost a million people in the UK. The evidence from this study – that a Viagra-like drug could reverse heart failure – should encourage further research in humans to determine if such drugs may help to save and improve lives.”
Source: Michael Lawless, Jessica L. Caldwell, Emma J. Radcliffe, et.al. Phosphodiesterase 5 inhibition improves contractile function and restores transverse tubule loss and catecholamine responsiveness in heart failure. Scientific Reports, 2019; 9 (1) DOI: 10.1038/s41598-019-42592-1