Comparison of transesophageal echocardiography versus computed tomography for detection of left atrial appendage filling defect (thrombus).

Patients with atrial fibrillation, who are referred for radiofrequency pulmonary vein antral isolation, frequently undergo transesophageal echocardiography (TEE) to detect and/or exclude left atrial or left atrial appendage (LAA) thrombus and cardiac computed tomographic angiography (CCTA) to define and/or evaluate left atrial and pulmonary venous anatomy. Previous studies have reported CCTA to have high sensitivity and negative predictive value (NPV) for detecting thrombus in the LAA. Previous studies determining an optimal LAA/ascending aorta (AA) Hounsfield unit (HU) density ratio for detection of LAA thrombus have been small, with limited numbers of thrombi. We thus sought to determine both the optimal cutoff for LAA HU density and LAA/AA HU density ratio in detecting LAA thrombus compared with TEE in a multicenter population. We included 84 patients who had undergone CCTA and TEE. LAA was evaluated by 64-row CCTA qualitatively (visual filling defect) and quantitatively (measurement of LAA HU density and LAA/AA HU density ratio), using a 1-cm area of interest in the same axial plane. Results were compared with TEE visualization of thrombus or spontaneous echo contrast. Qualitative identification of thrombus in LAA by CCTA compared with TEE detection of thrombus had a sensitivity of 100%, a specificity of 77.9%, a positive predictive value (PPV) of 51.6%, an NPV of 100%, and a total accuracy of 82.1%. The optimal LAA HU density cutoff for thrombus detection was 119 with a sensitivity of 88%, a specificity of 86%, PPV 56%, and an area under the curve of 0.923 (p = 0.0004). The optimal LAA/aorta HU ratio was 0.242 with a sensitivity of 87%, a specificity of 88%, a PPV of 64%, and an area under the curve of 0.921 (p = 0.0011). There is no significant difference (p = 0.72) between both areas under the curve, and both measurements improved the specificity and PPV compared with qualitative measures. Multidetector computed tomography is an imaging technique that can exclude LAA thrombus with very high NPV. Quantitative measurement of LAA HU density (cutoff 119) or LAA/aorta HU density ratio (cutoff 0.242) improves accuracy of positively detecting LAA thrombus. This technique is especially useful when delayed scanning is not performed and LAA is found incidentally after the patient scanning is complete.

Isovolumic cardiac contraction on high-temporal-resolution cine MR images: study in heart failure patients and healthy volunteers.

PURPOSE: To prospectively implement high-temporal-resolution cine magnetic resonance (MR) imaging protocol to compare cardiac preejection contraction (PEC) and prefilling relaxation (PFR) times between heart failure (HF) patients and healthy control subjects and to assess accuracy of PEC times to stratify HF patients, with ejection fraction (EF) and New York Heart Association (NYHA) symptom class as reference standards. MATERIALS AND METHODS: Following institutional review board approval of this HIPAA-compliant study and written informed consent, 18 healthy volunteers (10 women, eight men; mean age, 43 years +/- 14 [standard deviation]) and 18 HF patients (five women, 13 men; mean age, 49.8 years +/- 3) were imaged (breath-hold true fast imaging with steady-state precession, with temporal resolution of 5.6 msec at 1.5 T). By using left ventricular (LV) outflow tract acquisition, PEC phase was defined as time at QRS trigger to immediately before aortic valve opening. PFR was defined as time from initial aortic valve closure to immediately before mitral valve opening. Group means were compared (unpaired Student t test). Accuracy of PEC parameters in stratifying participants with severe systolic HF on the basis of EF and NYHA symptom class was assessed (receiver operating characteristic curve analysis). RESULTS: Compared with control subjects, HF patients had prolonged mean PEC time (40.4 msec +/- 11.8 vs 91.3 msec +/- 26, P < .001) and mean PFR time (68.3 msec +/- 26.8 vs 103.7 msec +/- 41.8, P < .01). PEC time correlated with global EF (r = -0.73, P < .001) and LV mass (r = 0.69, P < .001). For identification of patients with severe LV systolic dysfunction (EF 2), PEC time had good accuracy (AUC, 0.875 [P < .001]). CONCLUSION: It is feasible to assess isovolumic PEC and PFR phases of the cardiac cycle with high-frame-rate cine MR images, and PEC time is a surrogate measure of moderate-to-severe systolic HF.