Post-Procedure Monocyte Count Levels Predict Major Adverse Cardiovascular Events (MACE) Following Transcatheter Aortic Valve Implantation (TAVI) for Aortic Stenosis

Background Aortic stenosis has recently been characterised as having an inflammatory aetiology, beyond the traditional degenerative model. Recruitment of monocytes has been associated with inflammation contributing to progression of calcific aortic-valve disease. Prior research has demonstrated that pre- procedure inflammatory biomarkers do not consistently discriminate poorer outcomes in those with aortic stenosis. It remains, however, unclear if postprocedure inflammatory biomarkers, which are influenced by intraprocedural pro-inflammatory insults, can predict major adverse cardiovascular events (MACE) post transcatheter aortic valve implantation (TAVI). Method All patients with postprocedure monocyte levels undergoing transcatheter aortic valve implantation at The Alfred Hospital, Melbourne, Australia (2008-2019) were included. The highest monocyte count from postprocedure days 1 to 3 was used. Patients were divided into "high" or "low" postprocedure monocyte count groups using the Youden Index. The incidence of 30-day MACE a composite of stroke, acute myocardial infarction, and death) was then compared. Results In total, 472 patients were included (54% men, median age 84 years). Fourteen (14) patients (3%) suffered a 30-day MACE. Those with high postprocedure monocyte count were more likely to: be hypertensive (p=0.049); have a higher Society of Thoracic Surgeons risk score (p=0.032); and, undergo nontransfemoral access (p=0.018). A high (>= 0.975) postprocedure monocyte count was significantly associated with 30-day MACE (odds ratio [OR] 1.16 for each 0.1 increase in monocyte, p=0.025). This association remained present on multivariable analysis adjusted for age, sex, Society of Thoracic Surgeons risk score, and self-expanding valve prosthesis type (OR 1.17, p=0.028). Conclusions The association between postprocedure monocytosis and 30-day MACE suggests that minimising periprocedural inflammatory insults may improve outcomes. This inexpensive and readily available biomarker may also aid in tailored risk stratification for patients.