Background: Spontaneous echo contrast (SEC) is an important precursor for intracardiac thrombus and stroke. There are very limited data on characteristics of severe SEC and its impact on ischemic risk of nonvalvular atrial fibrillation (NVAF) patients after radiofrequency catheter ablation.
Methods: Transesophageal echocardiography files were reviewed between March 2009 and March 2021 in this monocentric retrospective study. SEC was classified into four levels. The primary endpoint was thromboembolic event (stroke, myocardial infarction, systemic embolism, and ensuing death), and the secondary endpoint included nonischemic mortality and recurrent atrial arrhythmia.
Results: Six hundred SEC cases were enrolled and classified into mild SEC group (Grade 1-2, n = 515) and severe SEC group (Grade 3-4, n = 85). Independent risk factors for severe SEC included higher brain natriuretic peptide (BNP), erythrocyte sedimentation rate (ESR), and LAd/∆LVED (LAd = left atrial diameter; ∆LVED = left ventricular end-diastolic diameter - left ventricular end-systolic diameter). The severe SEC group had a higher peri-procedural ischemic event occurrence (7.1 vs. 1.9%, p = 0.007). At a median follow-up of 55 months, the severe SEC group had a lower freedom rate from ischemic events (90.1 vs. 75.3%, p < 0.001); older age and severe SEC were independent risk factors for ischemic events. In patients undergoing redo-procedure (n = 100), a remarkably reduced ESR (17.8 ± 12.0 vs. 28.2 ± 19.0 mm/h, p < 0.001) was observed in patients whose SEC disappeared.
Conclusion: Higher BNP, ESR, and LAd/∆LVED were the independent predictors for severe SEC. Severe SEC was associated with higher peri-procedural and long-term ischemic risks. ESR and LAd/∆LVED, as indicators of hematological and hemodynamic change, seemed helpful in identifying NVAF patients prone to developing severe SEC.
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