RESUMO
Objective To evaluate the clinical value of cardiovascular dual-phase scan of 256-slice spiral CT in diagnosis of left atrial appendage (LAA) thrombus before radiofrequency ablation in patients with atrial fibrillation. Methods A prospective study was conducted. Thirty-six patients with atrial fibrillation being prepared to undergo radiofrequency ablation admitted to the Fifth Central Hospital of Tianjin from October 2015 toJuly 2016 were enrolled, they were scanned using dual-phase cardiovascular protocol of 256-slice spiral CT, and then trans-esophageal echocardiography (TEE) was performed for the definite diagnose of thrombus. In the first phase of cardiac CT, the intelligent tracking method was used to determine the delayed time; in the second phase cardiac CT scan, 85 seconds was confirmed as the delayed time; TEE as the golden standard was used to evaluate the value of dual-phase CT in definite diagnosis of LAA thrombus.Results LAA low density filling defect was discovered in 5 patients in the first phase CT scan, the CT scan in the second phase, the filling defect still existed, and the diagnosis of LAA thrombus in 3 patients was made (of them 2 cases after TEE examination were diagnosed definitely as LAA thrombus, and the echo in 1 case was smoke-like on TEE, being at pre-thrombus status), 2 cases were confirmed as pseudo-filling defects (afterwards, their diagnosis was confirmed as pre-thrombus status because the echo shown on TEE was smoke-like). Two patients were confirmed as true thrombi on TEE, and there were 3 patients diagnosed as pre-thrombus state by TEE because of their echo smoke-like. TEE was used as the golden standard for diagnosis of thrombus, the following indexes could be calculated: in the first phase, the sensitivity of using CT scan to diagnose LAA thrombus was 100.0%, the specificity 91.2%, positive predictive value (PPV) 40.0%, and negative predictive value (NPV) 100.0%; while in the second phase of using CT scan for diagnosis of LAA thrombus, the above indexes were 100.0%, 97.1%, 66.7%, 100.0% respectively; the CT Kappa coefficient of the second-phase was larger than that of the first-phase CT (0.898 vs. 0.739), the difference being statistically significant (P < 0.05).Conclusions Dual-phase cardiovascular protocol of CT can detecte of LAA thrombus/pre-thrombus state, the PPV is significantly elevated after the second phase of CT scan for diagnosis of thrombus, and the consistency between the second phase CT diagnosis of thrombus and TEE diagnosis is higher than that between the first phase CT and TEE, therefore, using dual-phase cardiovascular protocol of 256-slice spiral CT in diagnosis of LAA thrombus in patients with atrial fibrillation before radiofrequency ablation has relatively high application value.
