Key result
Double-contrast, single-phase computed tomography angiography prior to atrial fibrillation ablation demonstrated a 4.3% incidence of left atrial appendage filling defects and a 7.7% positive predictive value for thrombus.
Why the study?
Does double-contrast, single-phase computed tomography angiography accurately rule out left atrial appendage thrombus and reduce the need for transesophageal echocardiography prior to atrial fibrillation ablation?
Observational (n=477)
No
Does double-contrast, single-phase computed tomography angiography accurately rule out left atrial appendage thrombus and reduce the need for transesophageal echocardiography prior to atrial fibrillation ablation?
A double-contrast, single-phase CTA protocol prior to AF ablation results in a low incidence of LAA filling defects, safely reducing the need for transesophageal echocardiography to only those patients with high-risk filling defects.
Answers are grounded in this paper and cite their sources.
May limit TEE to high-risk cases before AF ablation; leaves open prospective validation of thromboembolic safety.
Prior to atrial fibrillation (AF) ablation, computed tomography angiography (CTA) is increasingly used for left atrial appendage (LAA) thrombus detection. LAA filling defects on CTA may represent thrombus or incomplete contrast mixing with blood. A pre-bolus of contrast material with delay before the CTA contrast bolus can help distinguish between thrombus and incomplete contrast mixing. We present results from a double-contrast, single-phase CTA protocol used in our daily clinical practice. In patients who underwent AF ablation between 2011 and 2015, double-contrast, single-phase CTA was performed prior to ablation. Two contrast boluses (30 and 70 ml) with 25-s interbolus delay were administered followed by prospectively triggered cardiac CTA. Only patients with left atrial (LA) or LAA filling defects underwent transesophageal echocardiography (TEE) to rule out thrombus. Prior to ablation, 605 CTA-scans were performed (median radiation dose: 3.1 mSv). In 579 CTA-scans (95.7 %), the LA and LAA completely filled with contrast. In 26 CTA-scans (4.3 %) the LAA showed a filling defect whereby thrombus could not be excluded. In 2 of those 26 patients (7.7 % and 0.3 % of the total population), TEE verified LAA thrombus. Low-risk LAA filling defects on CTA (n = 7/26) with an inhomogeneous aspect, Houndsfield Unit values >100, and an indefinite border were all caused by incomplete contrast mixing. No thromboembolic complications occurred perioperatively or during 6 months follow-up. Prior to AF ablation, incidence of LAA filling defects on double-contrast, single-phase CTA is low. TEE remains warranted in all but low-risk filling defects to rule out thrombus.
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Teunissen et al. (2016) conducted an observational in Symptomatic, drug-refractory or drug-intolerant atrial fibrillation (n=477). Double-contrast, single-phase computed tomography angiography vs. Transesophageal echocardiography (TEE) was evaluated on Incidence of left atrial appendage filling defects on CTA. Double-contrast, single-phase computed tomography angiography prior to atrial fibrillation ablation demonstrated a 4.3% incidence of left atrial appendage filling defects and a 7.7% positive predictive value for thrombus.
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