Infective endocarditis following valve surgery is a rare but life-threatening infection. In a new doctoral thesis from Karolinska Institutet, PhD student Lisa Bearpark from the Department of Molecular Medicine and Surgery investigates which patient groups are at particular risk for infective endocarditis.
What's the main focus of your thesis?
"My thesis explores how different patient groups fare after valve surgery for infective endocarditis-a life-threatening infection that affects the heart valves. Since approximately half of all patients who develop endocarditis require surgery, it is crucial to understand which groups are at particular risk. We have therefore studied patient populations that have previously been underrepresented in research, including individuals with intravenous drug use, bicuspid aortic valve, female patients, patients with pacemaker implants, and those with prosthetic valve endocarditis. The aim is to improve knowledge and, ultimately, the care provided to these vulnerable groups", says Lisa Bearpark , doctoral student at the Thoracic Surgery group, Department of Molecular Medicine and Surgery , Karolinska Institutet.
Which are the most important results?
"We found several important results that can contribute to better understanding and care for patients with endocarditis. Among people who inject drugs, the study showed that the surgery itself is successful, but the long-term prognosis is very poor, after six years, only 12% were alive and free from reinfection. The main reason was relapse to drug use, highlighting the need for integrated addiction care."
"Patients with bicuspid aortic valve accounted for about 25% of those undergoing surgery for aortic valve endocarditis. Despite the severity of the disease, this group had a significantly better prognosis than patients with tricuspid valves, which is important for risk assessment and follow-up."
"Pacemaker implantation during surgery was found to be a marker of a more invasive infection, but the pacemaker itself did not negatively affect survival."
"Regarding sex differences, our study showed that female patients had similar or slightly better survival than male patients after adjusting for age and comorbidities. This is particularly relevant since previous research has shown that females are referred for surgery less often than males."
"Finally, patients with prosthetic valve endocarditis in our study were, as expected, older and had more comorbidities, which led to higher postoperative mortality. However, those prosthetic valve endocarditis patients who survived surgery had a prognosis comparable to patients who had surgery for endocarditis in their native aortic valve."
How can this new knowledge contribute to the improvement of people's health?
"By identifying which patient groups face particular risks and have different prognoses following valve surgery for infective endocarditis, healthcare can become more personalized. This knowledge can support better surgical decision-making, more targeted follow-up, and improved collaboration with addiction services for patients who inject drugs. It can also help highlight areas that warrant further research, such as why women are referred for endocarditis surgery less frequently. Overall, these findings can contribute to more equitable and effective treatment, ultimately improving both survival and quality of life for patients with endocarditis."
What are your future ambitions?
"I plan to continue combining clinical work with research. I already have a new research project underway, also focusing on infective endocarditis, but this time including patients who do not undergo surgery. Although infective endocarditis is a relatively rare disease, its incidence is increasing globally, and there are still many unanswered questions to explore", says Lisa Bearpark.
Dissertation
Friday October 24, 2025 at 09:00, A4:04 Jan Lindsten, Eugeniavägen 3, Karolinska University Hospital Solna. Main Supervisor is Ulrik Sartipy.
Thesis
Clinical outcomes after valve surgery for infective endocarditis
