Abstract
Background/Objectives: Chronic subdural hematoma (cSDH) is a common disease of growing significance due to the increasing use of antithrombotic drugs and population aging. There exists conflicting observational evidence that previous treatment with angiotensin-converting enzyme (ACE) inhibitors reduces the rate of cSDH recurrence. This study assesses the hypothesis that ACE inhibitors may affect recurrence rates by altering hematoma membrane formation. Methods: All patients with chronic subdural hematoma who were operated upon in a single university hospital between 2015 and 2020 were considered for inclusion. Hematomas were classified according to their structural appearance in computed tomography (CT) imaging into one of eight subtypes. Patients' own medication, prior to hospitalization for cSDH treatment, was noted, and the use of ACI-inhibitors was identified. Results: Of the included 398 patients, 142 (35.9%) were treated with ACE inhibitors before admission for cSDH treatment. Of these, 115 patients (81.0%) received ramipril, 13 received patients lisinopril (11.3%), and 11 patients (9.6%) received enalapril. Reflecting cardiovascular comorbidity, patients on ACE inhibitors were more often simultaneously treated with antithrombotics (63.4% vs. 42.6%; p ≤ 0.001). Hematomas with homogenous hypodense (OR 11.739, 95%CI 2.570 to 53.612; p = 0.001), homogenous isodense (OR 12.204, 95%CI 2.669 to 55.798; p < 0.001), and homogenous hyperdense (OR 9.472, 95%CI 1.718 to 52.217; p < 0.001) architectures, as well as the prior use of ACE inhibitors (OR 2.026, 95%CI 1.214 to 3.384; p = 0.007), were independently associated with cSDH recurrence. Conclusions: Once corrected for hematoma architecture, type of surgery, and use of antithrombotic medication, preoperative use of ACE inhibitors was associated with a twofold increase in the likelihood of hematoma recurrence.