Walter Kernan, MD, professor of medicine (general medicine) retired on October 1, 2022, from his position as professor of medicine and transitioned to emeritus status with an appointment as senior research scientist.
Kernan came to Yale School of Medicine (YSM) in 1987 to work with Alvan Feinstein, MD, and Ralph Horwitz, MD, as a fellow in the Robert Wood Johnson Clinical Scholars Program (now the National Clinician Scholars Program). “My interest was understanding issues related to diagnosis, prognosis, and therapy for patients with transient ischemic attack and stroke of various etiologies. In the program, I learned skills that helped me start a research career. My career in research was not a forgone conclusion to me or my mentors. When I was awarded an NIH grant, a senior colleague told me, ‘Alvan would be surprised.’ To that I would say, “Alvan was a smart man!’”
After completing fellowship, Kernan was named an instructor of medicine in the Section of General Internal Medicine where he worked in the Primary Care Center, when it was located on Howard Avenue, and continued research on the care of patients with stroke. Early in his career, Kernan founded and directed the ambulatory component of the Internal Medicine clerkship for third-year students, one of the first required ambulatory experiences in any core medicine clerkship in the U.S.
When setting up the clerkship, he met Internist David Smith, MD, who had recently relocated to New Haven from Dartmouth Medical School where he had been working on a similar educational initiative. According to Smith, “an ambulatory clerkship was a novel idea at the time. Walter tapped me to establish a clinical site at Yale Health and work with him on the steering committee for his new clerkship. Twenty-five years later, Walter was instrumental in partnering with the Department of Psychiatry in developing the combined internal medicine psychiatry clerkship. The original clerkship in ambulatory care internal medicine was a big challenge and involved understanding the needs of the volunteer faculty, providing meaningful opportunities for them, including regular faculty development. There is strength and modesty with Walter. He didn't look for credit, but a lot of things he did had to be invented. They didn't exist beforehand.”
Based on his work in the clerkship, Kernan was elected president of the national organization of clerkship directors, Clerkship Directors in Internal Medicine, which is now part of the Alliance for Academic Internal Medicine. As his research commitments in the field of stroke increased after 2005, Kernan gradually spent more time on these until he stepped down as clerkship director in 2016 after nearly 25 years.
When asked what he most enjoyed about his work at Yale, Kernan cited his work teaching and practicing primary care but also his mentors, colleagues, and students. “[Dr. Lawrence] Larry Brass was an extraordinary stroke physician who, to my good fortune, started on the faculty about the same time I did. Starting in 1988, Larry and I teamed up with Ralph [Horowitz] and Catherine [Viscoli] for years of work investigating causes of stroke and the treatment and prognosis of patients with this illness. I am not alone in my experience that colleagues and students give meaning and pleasure to the important work we do,” says Kernan.
Catherine Viscoli, PhD, senior research scientist (general medicine) recalled those early days with Kernan. “Walter has been my friend and colleague since we met when he was a fellow with the Robert Wood Johnson Clinician Scholars Program, and I was a new research associate in General Medicine. This was multiple decades ago now! We were both mentees of Ralph Horwitz initially, and so gained a lot of clinical research experience in tandem – first on the Women’s Estrogen for Stroke Trial and Hemorrhagic Stroke Project and then on the IRIS trial.”
Viscoli would continue to collaborate with Kernan, along with Lawrence Young, MD, professor of medicine (cardiology) and of cellular and molecular physiology, and Silvio Inzucchi, MD, professor of medicine (endocrinology) in addition to other researchers across YSM and around the world on the Insulin Resistance Intervention after Stroke (IRIS) trial.
The collaboration between Inzucchi and Kernan started in the early 2000s when they became interested in insulin resistance as a risk factor for cardiovascular disease, specifically stroke. “A dialogue developed over a couple of years, and what emerged was the need to do some preliminary studies to see if we could safely administer an insulin-sensitizing drug, pioglitazone, to non-diabetic patients with prior stroke - a novel idea at the time. These pilots eventually led to the IRIS trial; Walter and I worked with Catherine Viscoli (project director), Larry Young (principal cardiologist), Peter Peduzzi (biostatistics), and Larry Brass (neurology) to design the trial. Walter was the PI on the project. With Catherine, he put together a large network of clinical sites across the world that eventually conducted the study successfully, leading to its landmark findings,” said Inzucchi.
“The IRIS trial was a huge undertaking – the largest stroke prevention study funded by the National Institute of Neurological Disorders and Stroke to date – and Walter led the trial with his typical, unwavering dedication to the highest principles of clinical research – as well as making it great fun for everyone,” said Viscoli. “His first and last thoughts were always about the patients who generously agreed to take part in research. Knowing that, I felt incredible lucky to work with and learn from him – and, over the years, to count him as a friend.”
The IRIS trial is considered a landmark trial in cardiovascular research.
Tragedy struck the IRIS team two years into the trial when YSM Neurologist Brass, died from lung cancer at age 49 in 2006. The loss was devastating to many who worked with Larry at Yale and elsewhere. “Larry was a special person,” recalled Kernan. “He was a young faculty member at Yale, very smart, charismatic, and caring of his patients and his coworkers. He just made work in neurology seem like the best thing in the world.”
After Brass passed away, Kernan invited Karen Furie, MD, MPH, to become the chief neurologist for the IRIS trial. Furie is currently chair of neurology at the Warren Alpert School of Brown University and chief of Neurology at Rhode Island Hospital and The Miriam Hospital. Kernan “is one of the most amazing people in the field,” said Furie. “It's been such a privilege to work with him in many different contexts, including clinical trials and numerous committees for the American Stroke Association and the National Institutes of Health. It's been a wonderful two decades of working closely with Walter. He is not only a tremendous scientist, but also an extraordinary writer, so he would be the person on the team who would write the first drafts and then be meticulous about the revisions and pooling everybody's comments.”
Scott Kasner, MD, Ruth M. and Tristram C. Colket, Jr. President's Distinguished Professor of Neurology, and chief, Division of Vascular Neurology, Department of Neurology, University of Pennsylvania, was a YSM medical student when he first met Kernan. They reconnected later at a stroke meeting, and Kernan invited him to participate in the IRIS trial. Kasner and Kernan would go on to partner on numerous guidelines for stroke prevention in addition to the IRIS trial. “At the last International Stroke Conference in 2022, Walter put together this program on primary care and stroke and how stroke neurologists and primary care doctors could better collaborate in the care of these patients. It was a great session. It really laid the groundwork for better partnerships and evolution over time,” said Kasner.
Kernan is now collaborating on more stroke research with Kevin Sheth, MD, professor of neurology and neurosurgery.
Sheth explained that in stroke prevention, there has been a long history of failure in clinical trials. “Walt ran one of the only stroke prevention trials that was positive. What Walt long recognized was that the way we have our system set up, when it comes to stroke care, we are largely sort of reactive and artificial. The system is set up for historical reasons to respond to disease but that doesn’t make sense. We want to prevent and treat risk factors not just disease, in this case, stroke. If someone has high blood pressure and a poor diet, they ultimately have the same common pathway for what leads to a heart attack as much as what leads to a stroke. To change the system to help patients, you need primary care practitioners working with stroke neurologists. He represented something groundbreaking, even today,” said Sheth.
Kernan plans to continue writing, teaching, and collaborating with colleagues in the YSM community. “My hope is to continue working in stroke prevention with Kevin Sheth, Richa Sharma, Adam de Havenon, Rachel Forman, Catherine Viscoli, and others. I’d like to work with junior faculty who are aiming at careers in clinical science. If I can find a way to help primary care to flourish and better establish its central role in U.S. healthcare, I’ll try for that too,” said Kernan. “I enjoy the work I do with the American Heart Association and the NIH and hope that continues. And, most importantly, I have a family; my wife works in oncology at Smilow Cancer Hospital and we have three children. Our oldest daughter had her first child this fall and I’m hoping to be called up for grandparent duty,” said Kernan.
“Walter is an incredibly thoughtful person. If I had stayed at Yale, I would have wanted him to be my primary care doctor. I saw the way he was with his patients. He considered all angles and was thoughtful and practical in his approach. Finding the right balance of those things is an incredible talent and he's the epitome of that,” said Kasner.
“Walter is one of the unique individuals who's been able to carve out a national and international role in stroke research without being a neurologist himself, which is quite remarkable,” said Inzucchi. “We all learned so much from him about conducting clinical trials, integrity in research, and keeping patients’ interests at the forefront.”
Sheth agrees, saying, “I think about the contributions he's made in clinical science where he has brought investigators from many fields together to help people, all while applying high standards and kindness. I feel like I've been super lucky in my career to date; in my future career if can be half the person and scientist he is, I will have knocked it out of the park.”
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