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Originally trained as a vet, Professor Philippe Pibarot (Institut Universitaire de Cardiologie et de Pneumologie de Québec, Department of Medicine, Laval University, Québec, Canada) has done substantial research in the field of cardiovascular imaging—specifically, looking at how best to diagnose low-gradient, low-flow aortic stenosis. He talks to Congress News about his career and the role of multimodal imaging in evaluating valvular heart disease, including how it can be used to assess Egyptian mummies.
You originally trained as a veterinarian. How did you come to be involved in researching imaging techniques for valvular heart disease?
After training in France (in Lyon), I moved to Canada for a one-year internship at the vet school of the University of Montreal. However, I subsequently started to work in the field of cardiovascular imaging research and did a PhD in human cardiology.
For some years, I was doing parallel work in humans and in animals; while I was researching prosthetic valves and the concept of patient-prosthesis mismatch, I was also doing clinical work at the vet school at the University of Montreal. However, these days, 90% of my research work is with humans.
What have been the key developments in cardiovascular imaging since you started working in this area?
When I started my career in the mid-1980s, cardiac catheterisation was still considered to be the gold standard approach for diagnosing valvular heart disease.
However, this has really changed over the years because we now have Doppler echocardiography (echo)—including 2D, colour Doppler, and tissue Doppler etc.—and this has replaced the cardiac catheterisation and angiogram as the standard approach for diagnosing and classifying valvular heart disease.
Also, with my colleague Doctor Marie-Annick Clavel, we have done a lot of work on the use of aortic valve calcium score, using computed tomography (CT), to assess the severity of aortic valve stenosis. This has become an important tool, which we have validated, and it is a highly reproducible method for predicting outcomes. However, perhaps the most important application of the score is the diagnosis of low-flow, low-gradient aortic stenosis.
Identifying severity in patients with low-flow, low-gradient aortic stenosis with resting echo alone can be challenging because you may have one parameter (the valve area) telling you that the stenosis is severe and another (the gradient) telling you that it is not. The aortic valve calcification score, via CT, is more about measuring anatomic severity than haemodynamic parameters; therefore, it is a useful tool for assessing patients with low-flow, low-gradient aortic stenosis.
What are other applications of multimodal imaging for assessing valvular heart disease?
For the management of valvular heart disease, multimodal imaging is crucial for various reasons. For example when considering performing aortic valve replacement, you need to be sure that there is an indication for intervention and, in some instances (e.g. when the patients has low-flow, low-gradient stenosis), multimodal imaging is essential for identifying that the patient has a true severe stenosis and needs valve replacement.
Also, with transcatheter aortic valve implantation (TAVI), multimodal imaging is important for selecting the right size of valve—if a too small size of valve is chosen, the risk of paravalvular leak increases. Multislice CT with contrast is now the most frequently used method for in-valve sizing. During follow-up, after TAVI, cardiac magnetic resonance (MR) imaging and CT may be useful additions to Doppler echo to assess valve integrity and function.
Another interesting aspect of multimodal imaging is that the cardiologists have been able to go back in time and review the presence of aortic stenosis in ancient Egypt; CT scans of unsealed mummies have been performed. This long post-mortem imaging investigation has revealed lesions in their coronary arteries, aortic and mitral valves—showing that coronary artery disease and valvular heart disease are very old diseases; they are not new diseases.
Therefore, with multimodal imaging, we are not only able to predict what may happen in a year’s or two years’ time, but we are also able to estimate what happened 4,000 years ago!
What advice would you give to someone who is just at the start of their research career?
I think the most important message is to never give up and never be discouraged. If you have a strong hypothesis, people may be sceptical and may criticise it, but I think it is important to listen to the criticism and to translate it into something that is constructive. After all, Albert Einstein was rejected for an associated professor position because his theory of relativity was considered to be “frivolous and artistic” rather than real science. So, sometimes it is important to perservere when you have had discouraging feedback.
Also, I would suggest that research fellows find a good mentor and this will not necessarily be in the places with the largest research centres. Potentially you could go to a prestigious centre and your mentor has so many other fellows there that you find you do not have sufficient time with him or her. Therefore, I would recommend, when selecting a mentor, take the pulse of the place and atmosphere; talk to other fellows that are working there to ensure the mentor will not be so busy that they will not able to speak to you.
Prof. Pibarot will be giving the talk “Why and how cardiac imaging has revolutionized the management of aortic stenosis” during “The research in imaging in the world—EuroEcho-Imaging Lecture”, which takes place tomorrow (Friday 8 December; 14.00–15.30 Evora).
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