Data from the Mitra FR trial, presented today at the annual meeting of the European Society of Cardiology, show Abbott’s MitraClip mitral valve repair device can treat secondary mitral regurgitation very successfully. The trouble is that this has no effect on patients’ prognoses.
The finding is not great news for Abbott since MitraClip is already widely used off-label in this indication – it is only approved for primary regurgitation, a much smaller population. With MitraClip forecast to be Abbott’s fifth biggest growth driver out to 2024, anything that might cause its use to be restricted will not be welcomed by the company.
Primary mitral regurgitation (MR), also called degenerative MR, is caused by a congenital malformation of the valve, which allows blood to leak back into the left atrium. In patients with secondary or functional MR, the valve is physically normal; regurgitation instead results from alterations in left ventricular structure and function.
Severe secondary MR is a predictor of poor clinical outcomes in patients with heart failure and reduced left ventricular ejection fraction. But it has not been clear whether it causes the poor prognosis or if it is a consequence along with poor outcomes, of wider cardiomyopathy. Neither has it been clear how best to treat the disorder.
The Mitra FR trial was small, with around 300 patients, but its conclusion is clear: treating secondary MR is “treating the consequence, not the cause”, according to lead investigator Jean-François Obadia of Hôpital Cardiovasculaire Louis Pradel, Lyon, France.
MitraClip can indeed treat secondary MR – at hospital discharge, 92% of patients had regurgitation reduced to mild or moderate and 76% had reduction to mild or trace.
On the primary endpoint of all-cause mortality or unplanned hospitalisations for heart failure at 12 months, however, there was no significant difference between patients treated with medication plus MitraClip and the control group, who were given drugs alone.
Delegates at the ESC were split on their interpretation of the data. Polled on whether they would consider the use of MitraClip and similar devices in patients with severe secondary MR ineligible for surgery, 57% said they would, if the patient had severe symptoms. However, 42% said they believed there was insufficient evidence to ever use the device.
Professor Obadia said that he did not think that off-label use of MitraClip should cease. “I wouldn’t say we are to definitively stop right now for secondary MR. It is a strong signal to be more selective – but not enough to say ‘no’.”
There might be subgroups in whom MitraClip is still a good option – those in whom drug therapy is contraindicated, for example, or those with arrhythmias, Prof Obadia said. But of all 14 subgroup analyses in Mitra FR, which included splits by heart failure severity, atrial fibrillation and ischaemic cardiomyopathy, none were able to show a benefit for MitraClip.
The future performance of Abbott’s structural heart unit will therefore partly be determined by whether or not cardiologists agree with Prof Obadia’s assessment.
|MitraClip - Abbott's fifth biggest growth driver|
|WW sales ($m)|
|Unit||Segment||Significant devices within segment||2018e||2020e||2022e||2024e||CAGR|
|Cardiovascular + Structural Heart||Transcatheter aortic valve replacement||Portico, acquired from St. Jude Medical||65||147||255||311||+27%|
|Diagnostics||Rapid diagnostics||Growth mainly due to Alere acquisition||2,068||2,203||2,393||2,585||+25%|
|Cardiovascular + Structural Heart||Left atrial appendage closure||Watchman||41||52||91||139||+21%|
|Diabetic Care||Glucose test systems||Freestyle Libre continuous glucose monitor||1,878||2,584||3,189||3,802||+15%|
|Cardiovascular + Structural Heart||MitraClip||MitraClip||526||698||883||1,095||+13%|
|Total MedTech Revenues||18,838||21,397||24,045||26,715||+7%|
|Total Company Revenues||30,776||34,609||38,658||42,757||+7%|