Karin Ludwigs: New insights into the diagnosis of peripheral artery disease
Chronic peripheral artery disease (PAD) reduces or stops blood flow to the lower limb, which can lead to amputation in the worst cases. Karin Ludwigs’ doctoral thesis could contribute to more consistent diagnosis and improved treatment of PAD.
KARIN LUDWIGS
Dissertation defense: 8 November 2024 (click for details)
Doctoral thesis: Prognostic factors for lower limb revascularization outcomes
Research area: Radiology and Imaging
Sahlgrenska Academy, The Institute of Clinical Sciences
Chronic peripheral artery disease is a serious condition where blood vessels in the lower limb become narrowed or blocked. The underlying cause is usually atherosclerosis, where the arteries become narrow and stiff due to fatty deposits and calcium building up as plaque on the interior arterial wall. Patients with PAD have a high risk of heart attack and stroke.
The most advanced form of PAD is called critical limb-threatening ischemia (CLTI). Typical symptoms include rest pain, non-healing ulcers, and tissue death (gangrene). Patients with CLTI are at high risk of leg amputation.
CLTI is often treated with revascularization, a procedure to restore blood flow. The blocked or narrowed artery is opened up either by open surgery (often with bypass) or by endovascular technique when the artery is widened with a balloon dilatation (arterial access through an introducer in the groin).
Inter-observer agreement
There are several clinical classification systems used to assess the severity of arterial lesions and occlusions in PAD. Lesion severity is evaluated based on images taken using both preoperative magnetic resonance angiography and digital subtraction angiography during the endovascular procedure.
“These classifications are important in research and for selecting the right treatment method for each patient. In my thesis, I examine the agreement in the assessment of disease severity, both between different observers and between two assessments by the same observer. Further, we also investigated if lesion severity, according to the classifications, can predict the chance of limb salvage” says Karin Ludwigs, a doctoral student at the Institute of Clinical Sciences and a vascular surgeon at Halland Hospital in Halmstad.
Reviewed 28,000 patients
Another part of her research focuses on describing how many patients experience what is known as a major adverse limb event (MALE) after revascularization, which includes acute ischemia, amputation and redo interventions.
“This has been reported in previous studies, but never before in a complete cohort of treated patients. We reviewed all 28,000 patients who underwent revascularization in Sweden between 2008 and 2016. We have learned that it is more common to have a MALE than previously thought. Of all patients treated for CLTI, 21-47% are estimated to experience a MALE within the first year after revascularization, depending on what definition of MALE used. Therefore, it is also important to agree on which definition of MALE to use in the future, to facilitate comparison of studies.”
Classifications need improvement
What are your most important research findings, and what practical benefits can they offer?
“Current anatomical classifications of PAD in the lower legs are not without problems, and the lesion severity does not seem to significantly affect the risk of future amputation after revascularization. There are other factors that likely play a bigger role for the outcome, such as outflow of blood (the foot’s artery status) and the clinical severity of PAD (symptoms and wound extent), the degree of ischemia (how severely blood flow to the limb has decreased), and any infections,” explains Karin Ludwigs.
She continues:
“Another important finding is the frequency of MALE after revascularization. This knowledge can lead to more informed decisions and better information for patients who will undergo such procedures.”
Fun to visualize research findings
What has been enjoyable and rewarding about your doctoral project?
“It has been fun to push a project forward over a long period of time. It leads to unexpected paths, and the result is not always what you initially expected. I have particularly enjoyed creating clear and simplified tables and figures for our findings. I have learned a lot within the field that helps me and my patients in the clinic.”
And what has been difficult and challenging?
“A few times, I have waited a long time for registry data or gotten stuck in data protection compliance issues (GDPR). That delayed the project and increased my frustration... The challenging but also rewarding part of projects like this is setting boundaries. What variables should we include, and why? Which results are the most exciting? Which results to highlight, and how?”
Text: Jakob Lundberg