Computed tomography angiography-based evaluation of left atrial appendage thrombi during non-invasive pre-procedural planning of transcatheter aortic valve replacement.

Transcatheter aortic valve replacement (TAVR) has emerged as an esteblished treatment for patients suffering from symptomatic severe aortic stenosis (AS). Despite its effectiveness, the procedure carries a risk of serious complications, including stroke, both during and after the intervention. Transoesophageal echocardiography (TOE) is regarded the gold standard for assessing the presence of potentially dangerous thrombi in the left atrial appendage (LAA). However, cardiac CT (cCT) has also shown promise in detecting LAA thrombi, particularly when employing specialized delayed contrast imaging protocols. Whether LAA thrombi can be identified during the TAVR pre-procedural planning cCT is unknown. Consequently, evaluation of LAA thrombi by cCT could improve the pre-procedural work-up and even make TOE redundant in many TAVR patients.

From March 2015 to February 2021, a total of 179 patients (93 men; mean age 80 years) with moderate to severe aortic stenosis (AS) were included in a retrospective single-center study. Each patient underwent both full-cycle cCT and TOE as part of their TAVR assessment. Clinical records and echocardiographic data were collected and cCT images evaluated by two independent investigators for the presence of thrombi in the left atrial appendage (LAA), measruement of contrast agent intensity in various cardiac locations and evaluation of structural features of the LAA. cCT demonstrated a remarkable pooled sensitivity of 100% and a acceptable pooled specificity of 74% for detecting LAA thrombi by TAVR evaluation cCT. Adding the parameter of minimal contrast agent intensity in LAA (HU_LAAmin) in a two-step diagnostic approach and defining a cut-off value for HU_LAAmin by ROC analysis, specificity could be raised up to 83%. Interestingly, despite the area of the LAA ostium, structural characteristics such as LAA volume, depth, configuration, and left atrial (LA) volume did not show significant differences between groups with and without LAA thrombi.

By using this two-step diagnostic approach, full-cycle cardiac CT demonstrated excellent sensitivity and good specificity in the pre-procedural evaluation of TAVR patients. Surprisingly, most structural features of the left atrial appendage (LAA) did not influence the presence of thrombi. These findings indicate that LAA thrombi can be reliably excluded in many patients by the pre-procedural cCT assessment for aortic valve stenosis. Thus, this study represents a significant advancement towards a fully non-invasive approach during TAVR evaluation.